1037 lines
41 KiB
Python
1037 lines
41 KiB
Python
from contextlib import contextmanager
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from sqlalchemy.types import NULLTYPE, Integer
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from sqlalchemy import schema as sa_schema
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from . import util
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from .compat import string_types
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from .ddl import impl
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__all__ = ('Operations',)
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try:
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from sqlalchemy.sql.naming import conv
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except:
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conv = None
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class Operations(object):
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"""Define high level migration operations.
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Each operation corresponds to some schema migration operation,
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executed against a particular :class:`.MigrationContext`
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which in turn represents connectivity to a database,
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or a file output stream.
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While :class:`.Operations` is normally configured as
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part of the :meth:`.EnvironmentContext.run_migrations`
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method called from an ``env.py`` script, a standalone
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:class:`.Operations` instance can be
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made for use cases external to regular Alembic
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migrations by passing in a :class:`.MigrationContext`::
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from alembic.migration import MigrationContext
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from alembic.operations import Operations
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conn = myengine.connect()
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ctx = MigrationContext.configure(conn)
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op = Operations(ctx)
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op.alter_column("t", "c", nullable=True)
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"""
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def __init__(self, migration_context):
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"""Construct a new :class:`.Operations`
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:param migration_context: a :class:`.MigrationContext`
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instance.
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"""
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self.migration_context = migration_context
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self.impl = migration_context.impl
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@classmethod
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@contextmanager
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def context(cls, migration_context):
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from .op import _install_proxy, _remove_proxy
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op = Operations(migration_context)
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_install_proxy(op)
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yield op
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_remove_proxy()
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def _primary_key_constraint(self, name, table_name, cols, schema=None):
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m = self._metadata()
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columns = [sa_schema.Column(n, NULLTYPE) for n in cols]
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t1 = sa_schema.Table(table_name, m,
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*columns,
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schema=schema)
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p = sa_schema.PrimaryKeyConstraint(*columns, name=name)
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t1.append_constraint(p)
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return p
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def _foreign_key_constraint(self, name, source, referent,
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local_cols, remote_cols,
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onupdate=None, ondelete=None,
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deferrable=None, source_schema=None,
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referent_schema=None, initially=None,
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match=None, **dialect_kw):
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m = self._metadata()
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if source == referent:
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t1_cols = local_cols + remote_cols
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else:
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t1_cols = local_cols
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sa_schema.Table(referent, m,
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*[sa_schema.Column(n, NULLTYPE) for n in remote_cols],
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schema=referent_schema)
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t1 = sa_schema.Table(source, m,
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*[sa_schema.Column(n, NULLTYPE) for n in t1_cols],
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schema=source_schema)
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tname = "%s.%s" % (referent_schema, referent) if referent_schema \
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else referent
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f = sa_schema.ForeignKeyConstraint(local_cols,
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["%s.%s" % (tname, n)
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for n in remote_cols],
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name=name,
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onupdate=onupdate,
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ondelete=ondelete,
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deferrable=deferrable,
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initially=initially,
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match=match,
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**dialect_kw
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)
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t1.append_constraint(f)
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return f
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def _unique_constraint(self, name, source, local_cols, schema=None, **kw):
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t = sa_schema.Table(source, self._metadata(),
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*[sa_schema.Column(n, NULLTYPE) for n in local_cols],
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schema=schema)
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kw['name'] = name
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uq = sa_schema.UniqueConstraint(*[t.c[n] for n in local_cols], **kw)
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# TODO: need event tests to ensure the event
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# is fired off here
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t.append_constraint(uq)
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return uq
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def _check_constraint(self, name, source, condition, schema=None, **kw):
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t = sa_schema.Table(source, self._metadata(),
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sa_schema.Column('x', Integer), schema=schema)
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ck = sa_schema.CheckConstraint(condition, name=name, **kw)
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t.append_constraint(ck)
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return ck
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def _metadata(self):
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kw = {}
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if 'target_metadata' in self.migration_context.opts:
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mt = self.migration_context.opts['target_metadata']
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if hasattr(mt, 'naming_convention'):
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kw['naming_convention'] = mt.naming_convention
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return sa_schema.MetaData(**kw)
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def _table(self, name, *columns, **kw):
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m = self._metadata()
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t = sa_schema.Table(name, m, *columns, **kw)
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for f in t.foreign_keys:
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self._ensure_table_for_fk(m, f)
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return t
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def _column(self, name, type_, **kw):
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return sa_schema.Column(name, type_, **kw)
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def _index(self, name, tablename, columns, schema=None, **kw):
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t = sa_schema.Table(tablename or 'no_table', self._metadata(),
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*[sa_schema.Column(n, NULLTYPE) for n in columns],
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schema=schema
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)
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return sa_schema.Index(name, *[t.c[n] for n in columns], **kw)
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def _parse_table_key(self, table_key):
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if '.' in table_key:
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tokens = table_key.split('.')
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sname = ".".join(tokens[0:-1])
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tname = tokens[-1]
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else:
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tname = table_key
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sname = None
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return (sname, tname)
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def _ensure_table_for_fk(self, metadata, fk):
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"""create a placeholder Table object for the referent of a
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ForeignKey.
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"""
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if isinstance(fk._colspec, string_types):
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table_key, cname = fk._colspec.rsplit('.', 1)
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sname, tname = self._parse_table_key(table_key)
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if table_key not in metadata.tables:
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rel_t = sa_schema.Table(tname, metadata, schema=sname)
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else:
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rel_t = metadata.tables[table_key]
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if cname not in rel_t.c:
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rel_t.append_column(sa_schema.Column(cname, NULLTYPE))
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def get_context(self):
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"""Return the :class:`.MigrationContext` object that's
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currently in use.
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"""
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return self.migration_context
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def rename_table(self, old_table_name, new_table_name, schema=None):
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"""Emit an ALTER TABLE to rename a table.
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:param old_table_name: old name.
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:param new_table_name: new name.
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:param schema: Optional schema name to operate within.
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"""
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self.impl.rename_table(
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old_table_name,
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new_table_name,
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schema=schema
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)
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@util._with_legacy_names([('name', 'new_column_name')])
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def alter_column(self, table_name, column_name,
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nullable=None,
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server_default=False,
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new_column_name=None,
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type_=None,
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autoincrement=None,
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existing_type=None,
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existing_server_default=False,
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existing_nullable=None,
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existing_autoincrement=None,
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schema=None
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):
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"""Issue an "alter column" instruction using the
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current migration context.
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Generally, only that aspect of the column which
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is being changed, i.e. name, type, nullability,
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default, needs to be specified. Multiple changes
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can also be specified at once and the backend should
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"do the right thing", emitting each change either
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separately or together as the backend allows.
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MySQL has special requirements here, since MySQL
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cannot ALTER a column without a full specification.
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When producing MySQL-compatible migration files,
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it is recommended that the ``existing_type``,
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``existing_server_default``, and ``existing_nullable``
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parameters be present, if not being altered.
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Type changes which are against the SQLAlchemy
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"schema" types :class:`~sqlalchemy.types.Boolean`
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and :class:`~sqlalchemy.types.Enum` may also
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add or drop constraints which accompany those
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types on backends that don't support them natively.
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The ``existing_server_default`` argument is
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used in this case as well to remove a previous
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constraint.
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:param table_name: string name of the target table.
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:param column_name: string name of the target column,
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as it exists before the operation begins.
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:param nullable: Optional; specify ``True`` or ``False``
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to alter the column's nullability.
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:param server_default: Optional; specify a string
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SQL expression, :func:`~sqlalchemy.sql.expression.text`,
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or :class:`~sqlalchemy.schema.DefaultClause` to indicate
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an alteration to the column's default value.
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Set to ``None`` to have the default removed.
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:param new_column_name: Optional; specify a string name here to
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indicate the new name within a column rename operation.
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.. versionchanged:: 0.5.0
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The ``name`` parameter is now named ``new_column_name``.
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The old name will continue to function for backwards
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compatibility.
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:param ``type_``: Optional; a :class:`~sqlalchemy.types.TypeEngine`
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type object to specify a change to the column's type.
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For SQLAlchemy types that also indicate a constraint (i.e.
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:class:`~sqlalchemy.types.Boolean`, :class:`~sqlalchemy.types.Enum`),
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the constraint is also generated.
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:param autoincrement: set the ``AUTO_INCREMENT`` flag of the column;
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currently understood by the MySQL dialect.
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:param existing_type: Optional; a
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:class:`~sqlalchemy.types.TypeEngine`
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type object to specify the previous type. This
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is required for all MySQL column alter operations that
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don't otherwise specify a new type, as well as for
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when nullability is being changed on a SQL Server
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column. It is also used if the type is a so-called
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SQLlchemy "schema" type which may define a constraint (i.e.
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:class:`~sqlalchemy.types.Boolean`,
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:class:`~sqlalchemy.types.Enum`),
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so that the constraint can be dropped.
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:param existing_server_default: Optional; The existing
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default value of the column. Required on MySQL if
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an existing default is not being changed; else MySQL
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removes the default.
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:param existing_nullable: Optional; the existing nullability
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of the column. Required on MySQL if the existing nullability
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is not being changed; else MySQL sets this to NULL.
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:param existing_autoincrement: Optional; the existing autoincrement
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of the column. Used for MySQL's system of altering a column
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that specifies ``AUTO_INCREMENT``.
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:param schema: Optional schema name to operate within.
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.. versionadded:: 0.4.0
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"""
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compiler = self.impl.dialect.statement_compiler(
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self.impl.dialect,
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None
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)
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def _count_constraint(constraint):
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return not isinstance(constraint, sa_schema.PrimaryKeyConstraint) and \
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(not constraint._create_rule or
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constraint._create_rule(compiler))
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if existing_type and type_:
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t = self._table(table_name,
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sa_schema.Column(column_name, existing_type),
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schema=schema
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)
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for constraint in t.constraints:
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if _count_constraint(constraint):
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self.impl.drop_constraint(constraint)
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self.impl.alter_column(table_name, column_name,
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nullable=nullable,
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server_default=server_default,
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name=new_column_name,
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type_=type_,
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schema=schema,
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autoincrement=autoincrement,
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existing_type=existing_type,
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existing_server_default=existing_server_default,
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existing_nullable=existing_nullable,
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existing_autoincrement=existing_autoincrement
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)
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if type_:
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t = self._table(table_name,
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sa_schema.Column(column_name, type_),
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schema=schema
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)
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for constraint in t.constraints:
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if _count_constraint(constraint):
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self.impl.add_constraint(constraint)
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def f(self, name):
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"""Indicate a string name that has already had a naming convention
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applied to it.
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This feature combines with the SQLAlchemy ``naming_convention`` feature
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to disambiguate constraint names that have already had naming
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conventions applied to them, versus those that have not. This is
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necessary in the case that the ``"%(constraint_name)s"`` token
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is used within a naming convention, so that it can be identified
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that this particular name should remain fixed.
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If the :meth:`.Operations.f` is used on a constraint, the naming
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convention will not take effect::
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op.add_column('t', 'x', Boolean(name=op.f('ck_bool_t_x')))
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Above, the CHECK constraint generated will have the name ``ck_bool_t_x``
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regardless of whether or not a naming convention is in use.
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Alternatively, if a naming convention is in use, and 'f' is not used,
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names will be converted along conventions. If the ``target_metadata``
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contains the naming convention
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``{"ck": "ck_bool_%(table_name)s_%(constraint_name)s"}``, then the
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output of the following:
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op.add_column('t', 'x', Boolean(name='x'))
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will be::
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CONSTRAINT ck_bool_t_x CHECK (x in (1, 0)))
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The function is rendered in the output of autogenerate when
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a particular constraint name is already converted, for SQLAlchemy
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version **0.9.4 and greater only**. Even though ``naming_convention``
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was introduced in 0.9.2, the string disambiguation service is new
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as of 0.9.4.
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.. versionadded:: 0.6.4
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"""
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if conv:
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return conv(name)
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else:
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raise NotImplementedError(
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"op.f() feature requires SQLAlchemy 0.9.4 or greater.")
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def add_column(self, table_name, column, schema=None):
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"""Issue an "add column" instruction using the current
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migration context.
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e.g.::
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from alembic import op
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from sqlalchemy import Column, String
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op.add_column('organization',
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Column('name', String())
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)
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The provided :class:`~sqlalchemy.schema.Column` object can also
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specify a :class:`~sqlalchemy.schema.ForeignKey`, referencing
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a remote table name. Alembic will automatically generate a stub
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"referenced" table and emit a second ALTER statement in order
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to add the constraint separately::
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from alembic import op
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from sqlalchemy import Column, INTEGER, ForeignKey
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op.add_column('organization',
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Column('account_id', INTEGER, ForeignKey('accounts.id'))
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)
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Note that this statement uses the :class:`~sqlalchemy.schema.Column`
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construct as is from the SQLAlchemy library. In particular,
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default values to be created on the database side are
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specified using the ``server_default`` parameter, and not
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``default`` which only specifies Python-side defaults::
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from alembic import op
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from sqlalchemy import Column, TIMESTAMP, func
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# specify "DEFAULT NOW" along with the column add
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op.add_column('account',
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Column('timestamp', TIMESTAMP, server_default=func.now())
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)
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:param table_name: String name of the parent table.
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:param column: a :class:`sqlalchemy.schema.Column` object
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representing the new column.
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:param schema: Optional schema name to operate within.
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.. versionadded:: 0.4.0
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"""
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t = self._table(table_name, column, schema=schema)
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self.impl.add_column(
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table_name,
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column,
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schema=schema
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)
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for constraint in t.constraints:
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if not isinstance(constraint, sa_schema.PrimaryKeyConstraint):
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self.impl.add_constraint(constraint)
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def drop_column(self, table_name, column_name, **kw):
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"""Issue a "drop column" instruction using the current
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migration context.
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e.g.::
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drop_column('organization', 'account_id')
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:param table_name: name of table
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:param column_name: name of column
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:param schema: Optional schema name to operate within.
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.. versionadded:: 0.4.0
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:param mssql_drop_check: Optional boolean. When ``True``, on
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Microsoft SQL Server only, first
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drop the CHECK constraint on the column using a
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SQL-script-compatible
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block that selects into a @variable from sys.check_constraints,
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then exec's a separate DROP CONSTRAINT for that constraint.
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:param mssql_drop_default: Optional boolean. When ``True``, on
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Microsoft SQL Server only, first
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drop the DEFAULT constraint on the column using a
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SQL-script-compatible
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block that selects into a @variable from sys.default_constraints,
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then exec's a separate DROP CONSTRAINT for that default.
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:param mssql_drop_foreign_key: Optional boolean. When ``True``, on
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Microsoft SQL Server only, first
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drop a single FOREIGN KEY constraint on the column using a
|
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SQL-script-compatible
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block that selects into a @variable from
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sys.foreign_keys/sys.foreign_key_columns,
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then exec's a separate DROP CONSTRAINT for that default. Only
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works if the column has exactly one FK constraint which refers to
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it, at the moment.
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.. versionadded:: 0.6.2
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"""
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self.impl.drop_column(
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table_name,
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self._column(column_name, NULLTYPE),
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**kw
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)
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|
|
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def create_primary_key(self, name, table_name, cols, schema=None):
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"""Issue a "create primary key" instruction using the current
|
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migration context.
|
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e.g.::
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from alembic import op
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op.create_primary_key(
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"pk_my_table", "my_table",
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["id", "version"]
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)
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This internally generates a :class:`~sqlalchemy.schema.Table` object
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containing the necessary columns, then generates a new
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:class:`~sqlalchemy.schema.PrimaryKeyConstraint`
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object which it then associates with the :class:`~sqlalchemy.schema.Table`.
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Any event listeners associated with this action will be fired
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off normally. The :class:`~sqlalchemy.schema.AddConstraint`
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construct is ultimately used to generate the ALTER statement.
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|
|
.. versionadded:: 0.5.0
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:param name: Name of the primary key constraint. The name is necessary
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so that an ALTER statement can be emitted. For setups that
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use an automated naming scheme such as that described at
|
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`NamingConventions <http://www.sqlalchemy.org/trac/wiki/UsageRecipes/NamingConventions>`_,
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``name`` here can be ``None``, as the event listener will
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apply the name to the constraint object when it is associated
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with the table.
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:param table_name: String name of the target table.
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:param cols: a list of string column names to be applied to the
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primary key constraint.
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:param schema: Optional schema name of the table.
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|
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"""
|
|
self.impl.add_constraint(
|
|
self._primary_key_constraint(name, table_name, cols,
|
|
schema)
|
|
)
|
|
|
|
|
|
def create_foreign_key(self, name, source, referent, local_cols,
|
|
remote_cols, onupdate=None, ondelete=None,
|
|
deferrable=None, initially=None, match=None,
|
|
source_schema=None, referent_schema=None,
|
|
**dialect_kw):
|
|
"""Issue a "create foreign key" instruction using the
|
|
current migration context.
|
|
|
|
e.g.::
|
|
|
|
from alembic import op
|
|
op.create_foreign_key(
|
|
"fk_user_address", "address",
|
|
"user", ["user_id"], ["id"])
|
|
|
|
This internally generates a :class:`~sqlalchemy.schema.Table` object
|
|
containing the necessary columns, then generates a new
|
|
:class:`~sqlalchemy.schema.ForeignKeyConstraint`
|
|
object which it then associates with the :class:`~sqlalchemy.schema.Table`.
|
|
Any event listeners associated with this action will be fired
|
|
off normally. The :class:`~sqlalchemy.schema.AddConstraint`
|
|
construct is ultimately used to generate the ALTER statement.
|
|
|
|
:param name: Name of the foreign key constraint. The name is necessary
|
|
so that an ALTER statement can be emitted. For setups that
|
|
use an automated naming scheme such as that described at
|
|
`NamingConventions <http://www.sqlalchemy.org/trac/wiki/UsageRecipes/NamingConventions>`_,
|
|
``name`` here can be ``None``, as the event listener will
|
|
apply the name to the constraint object when it is associated
|
|
with the table.
|
|
:param source: String name of the source table.
|
|
:param referent: String name of the destination table.
|
|
:param local_cols: a list of string column names in the
|
|
source table.
|
|
:param remote_cols: a list of string column names in the
|
|
remote table.
|
|
:param onupdate: Optional string. If set, emit ON UPDATE <value> when
|
|
issuing DDL for this constraint. Typical values include CASCADE,
|
|
DELETE and RESTRICT.
|
|
:param ondelete: Optional string. If set, emit ON DELETE <value> when
|
|
issuing DDL for this constraint. Typical values include CASCADE,
|
|
DELETE and RESTRICT.
|
|
:param deferrable: optional bool. If set, emit DEFERRABLE or NOT
|
|
DEFERRABLE when issuing DDL for this constraint.
|
|
:param source_schema: Optional schema name of the source table.
|
|
:param referent_schema: Optional schema name of the destination table.
|
|
|
|
"""
|
|
|
|
self.impl.add_constraint(
|
|
self._foreign_key_constraint(name, source, referent,
|
|
local_cols, remote_cols,
|
|
onupdate=onupdate, ondelete=ondelete,
|
|
deferrable=deferrable, source_schema=source_schema,
|
|
referent_schema=referent_schema,
|
|
initially=initially, match=match, **dialect_kw)
|
|
)
|
|
|
|
def create_unique_constraint(self, name, source, local_cols,
|
|
schema=None, **kw):
|
|
"""Issue a "create unique constraint" instruction using the
|
|
current migration context.
|
|
|
|
e.g.::
|
|
|
|
from alembic import op
|
|
op.create_unique_constraint("uq_user_name", "user", ["name"])
|
|
|
|
This internally generates a :class:`~sqlalchemy.schema.Table` object
|
|
containing the necessary columns, then generates a new
|
|
:class:`~sqlalchemy.schema.UniqueConstraint`
|
|
object which it then associates with the :class:`~sqlalchemy.schema.Table`.
|
|
Any event listeners associated with this action will be fired
|
|
off normally. The :class:`~sqlalchemy.schema.AddConstraint`
|
|
construct is ultimately used to generate the ALTER statement.
|
|
|
|
:param name: Name of the unique constraint. The name is necessary
|
|
so that an ALTER statement can be emitted. For setups that
|
|
use an automated naming scheme such as that described at
|
|
`NamingConventions <http://www.sqlalchemy.org/trac/wiki/UsageRecipes/NamingConventions>`_,
|
|
``name`` here can be ``None``, as the event listener will
|
|
apply the name to the constraint object when it is associated
|
|
with the table.
|
|
:param source: String name of the source table. Dotted schema names are
|
|
supported.
|
|
:param local_cols: a list of string column names in the
|
|
source table.
|
|
:param deferrable: optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when
|
|
issuing DDL for this constraint.
|
|
:param initially: optional string. If set, emit INITIALLY <value> when issuing DDL
|
|
for this constraint.
|
|
:param schema: Optional schema name to operate within.
|
|
|
|
.. versionadded:: 0.4.0
|
|
|
|
"""
|
|
|
|
self.impl.add_constraint(
|
|
self._unique_constraint(name, source, local_cols,
|
|
schema=schema, **kw)
|
|
)
|
|
|
|
def create_check_constraint(self, name, source, condition,
|
|
schema=None, **kw):
|
|
"""Issue a "create check constraint" instruction using the
|
|
current migration context.
|
|
|
|
e.g.::
|
|
|
|
from alembic import op
|
|
from sqlalchemy.sql import column, func
|
|
|
|
op.create_check_constraint(
|
|
"ck_user_name_len",
|
|
"user",
|
|
func.len(column('name')) > 5
|
|
)
|
|
|
|
CHECK constraints are usually against a SQL expression, so ad-hoc
|
|
table metadata is usually needed. The function will convert the given
|
|
arguments into a :class:`sqlalchemy.schema.CheckConstraint` bound
|
|
to an anonymous table in order to emit the CREATE statement.
|
|
|
|
:param name: Name of the check constraint. The name is necessary
|
|
so that an ALTER statement can be emitted. For setups that
|
|
use an automated naming scheme such as that described at
|
|
`NamingConventions <http://www.sqlalchemy.org/trac/wiki/UsageRecipes/NamingConventions>`_,
|
|
``name`` here can be ``None``, as the event listener will
|
|
apply the name to the constraint object when it is associated
|
|
with the table.
|
|
:param source: String name of the source table.
|
|
:param condition: SQL expression that's the condition of the constraint.
|
|
Can be a string or SQLAlchemy expression language structure.
|
|
:param deferrable: optional bool. If set, emit DEFERRABLE or NOT DEFERRABLE when
|
|
issuing DDL for this constraint.
|
|
:param initially: optional string. If set, emit INITIALLY <value> when issuing DDL
|
|
for this constraint.
|
|
:param schema: Optional schema name to operate within.
|
|
|
|
..versionadded:: 0.4.0
|
|
|
|
"""
|
|
self.impl.add_constraint(
|
|
self._check_constraint(name, source, condition, schema=schema, **kw)
|
|
)
|
|
|
|
def create_table(self, name, *columns, **kw):
|
|
"""Issue a "create table" instruction using the current migration context.
|
|
|
|
This directive receives an argument list similar to that of the
|
|
traditional :class:`sqlalchemy.schema.Table` construct, but without the
|
|
metadata::
|
|
|
|
from sqlalchemy import INTEGER, VARCHAR, NVARCHAR, Column
|
|
from alembic import op
|
|
|
|
op.create_table(
|
|
'account',
|
|
Column('id', INTEGER, primary_key=True),
|
|
Column('name', VARCHAR(50), nullable=False),
|
|
Column('description', NVARCHAR(200))
|
|
Column('timestamp', TIMESTAMP, server_default=func.now())
|
|
)
|
|
|
|
Note that :meth:`.create_table` accepts :class:`~sqlalchemy.schema.Column`
|
|
constructs directly from the SQLAlchemy library. In particular,
|
|
default values to be created on the database side are
|
|
specified using the ``server_default`` parameter, and not
|
|
``default`` which only specifies Python-side defaults::
|
|
|
|
from alembic import op
|
|
from sqlalchemy import Column, TIMESTAMP, func
|
|
|
|
# specify "DEFAULT NOW" along with the "timestamp" column
|
|
op.create_table('account',
|
|
Column('id', INTEGER, primary_key=True),
|
|
Column('timestamp', TIMESTAMP, server_default=func.now())
|
|
)
|
|
|
|
:param name: Name of the table
|
|
:param \*columns: collection of :class:`~sqlalchemy.schema.Column`
|
|
objects within
|
|
the table, as well as optional :class:`~sqlalchemy.schema.Constraint`
|
|
objects
|
|
and :class:`~.sqlalchemy.schema.Index` objects.
|
|
:param schema: Optional schema name to operate within.
|
|
:param \**kw: Other keyword arguments are passed to the underlying
|
|
:class:`sqlalchemy.schema.Table` object created for the command.
|
|
|
|
"""
|
|
self.impl.create_table(
|
|
self._table(name, *columns, **kw)
|
|
)
|
|
|
|
def drop_table(self, name, **kw):
|
|
"""Issue a "drop table" instruction using the current
|
|
migration context.
|
|
|
|
|
|
e.g.::
|
|
|
|
drop_table("accounts")
|
|
|
|
:param name: Name of the table
|
|
:param schema: Optional schema name to operate within.
|
|
|
|
.. versionadded:: 0.4.0
|
|
|
|
:param \**kw: Other keyword arguments are passed to the underlying
|
|
:class:`sqlalchemy.schema.Table` object created for the command.
|
|
|
|
"""
|
|
self.impl.drop_table(
|
|
self._table(name, **kw)
|
|
)
|
|
|
|
def create_index(self, name, table_name, columns, schema=None, **kw):
|
|
"""Issue a "create index" instruction using the current
|
|
migration context.
|
|
|
|
e.g.::
|
|
|
|
from alembic import op
|
|
op.create_index('ik_test', 't1', ['foo', 'bar'])
|
|
|
|
:param name: name of the index.
|
|
:param table_name: name of the owning table.
|
|
|
|
.. versionchanged:: 0.5.0
|
|
The ``tablename`` parameter is now named ``table_name``.
|
|
As this is a positional argument, the old name is no
|
|
longer present.
|
|
|
|
:param columns: a list of string column names in the
|
|
table.
|
|
:param schema: Optional schema name to operate within.
|
|
|
|
.. versionadded:: 0.4.0
|
|
|
|
"""
|
|
|
|
self.impl.create_index(
|
|
self._index(name, table_name, columns, schema=schema, **kw)
|
|
)
|
|
|
|
@util._with_legacy_names([('tablename', 'table_name')])
|
|
def drop_index(self, name, table_name=None, schema=None):
|
|
"""Issue a "drop index" instruction using the current
|
|
migration context.
|
|
|
|
e.g.::
|
|
|
|
drop_index("accounts")
|
|
|
|
:param name: name of the index.
|
|
:param table_name: name of the owning table. Some
|
|
backends such as Microsoft SQL Server require this.
|
|
|
|
.. versionchanged:: 0.5.0
|
|
The ``tablename`` parameter is now named ``table_name``.
|
|
The old name will continue to function for backwards
|
|
compatibility.
|
|
|
|
:param schema: Optional schema name to operate within.
|
|
|
|
.. versionadded:: 0.4.0
|
|
|
|
"""
|
|
# need a dummy column name here since SQLAlchemy
|
|
# 0.7.6 and further raises on Index with no columns
|
|
self.impl.drop_index(
|
|
self._index(name, table_name, ['x'], schema=schema)
|
|
)
|
|
|
|
@util._with_legacy_names([("type", "type_")])
|
|
def drop_constraint(self, name, table_name, type_=None, schema=None):
|
|
"""Drop a constraint of the given name, typically via DROP CONSTRAINT.
|
|
|
|
:param name: name of the constraint.
|
|
:param table_name: table name.
|
|
|
|
.. versionchanged:: 0.5.0
|
|
The ``tablename`` parameter is now named ``table_name``.
|
|
As this is a positional argument, the old name is no
|
|
longer present.
|
|
|
|
:param ``type_``: optional, required on MySQL. can be
|
|
'foreignkey', 'primary', 'unique', or 'check'.
|
|
|
|
.. versionchanged:: 0.5.0
|
|
The ``type`` parameter is now named ``type_``. The old name
|
|
``type`` will remain for backwards compatibility.
|
|
|
|
.. versionadded:: 0.3.6 'primary' qualfier to enable
|
|
dropping of MySQL primary key constraints.
|
|
|
|
:param schema: Optional schema name to operate within.
|
|
|
|
.. versionadded:: 0.4.0
|
|
|
|
"""
|
|
|
|
t = self._table(table_name, schema=schema)
|
|
types = {
|
|
'foreignkey': lambda name: sa_schema.ForeignKeyConstraint(
|
|
[], [], name=name),
|
|
'primary': sa_schema.PrimaryKeyConstraint,
|
|
'unique': sa_schema.UniqueConstraint,
|
|
'check': lambda name: sa_schema.CheckConstraint("", name=name),
|
|
None: sa_schema.Constraint
|
|
}
|
|
try:
|
|
const = types[type_]
|
|
except KeyError:
|
|
raise TypeError("'type' can be one of %s" %
|
|
", ".join(sorted(repr(x) for x in types)))
|
|
|
|
const = const(name=name)
|
|
t.append_constraint(const)
|
|
self.impl.drop_constraint(const)
|
|
|
|
def bulk_insert(self, table, rows, multiinsert=True):
|
|
"""Issue a "bulk insert" operation using the current
|
|
migration context.
|
|
|
|
This provides a means of representing an INSERT of multiple rows
|
|
which works equally well in the context of executing on a live
|
|
connection as well as that of generating a SQL script. In the
|
|
case of a SQL script, the values are rendered inline into the
|
|
statement.
|
|
|
|
e.g.::
|
|
|
|
from alembic import op
|
|
from datetime import date
|
|
from sqlalchemy.sql import table, column
|
|
from sqlalchemy import String, Integer, Date
|
|
|
|
# Create an ad-hoc table to use for the insert statement.
|
|
accounts_table = table('account',
|
|
column('id', Integer),
|
|
column('name', String),
|
|
column('create_date', Date)
|
|
)
|
|
|
|
op.bulk_insert(accounts_table,
|
|
[
|
|
{'id':1, 'name':'John Smith',
|
|
'create_date':date(2010, 10, 5)},
|
|
{'id':2, 'name':'Ed Williams',
|
|
'create_date':date(2007, 5, 27)},
|
|
{'id':3, 'name':'Wendy Jones',
|
|
'create_date':date(2008, 8, 15)},
|
|
]
|
|
)
|
|
|
|
When using --sql mode, some datatypes may not render inline automatically,
|
|
such as dates and other special types. When this issue is present,
|
|
:meth:`.Operations.inline_literal` may be used::
|
|
|
|
op.bulk_insert(accounts_table,
|
|
[
|
|
{'id':1, 'name':'John Smith',
|
|
'create_date':op.inline_literal("2010-10-05")},
|
|
{'id':2, 'name':'Ed Williams',
|
|
'create_date':op.inline_literal("2007-05-27")},
|
|
{'id':3, 'name':'Wendy Jones',
|
|
'create_date':op.inline_literal("2008-08-15")},
|
|
],
|
|
multiinsert=False
|
|
)
|
|
|
|
When using :meth:`.Operations.inline_literal` in conjunction with
|
|
:meth:`.Operations.bulk_insert`, in order for the statement to work
|
|
in "online" (e.g. non --sql) mode, the
|
|
:paramref:`~.Operations.bulk_insert.multiinsert`
|
|
flag should be set to ``False``, which will have the effect of
|
|
individual INSERT statements being emitted to the database, each
|
|
with a distinct VALUES clause, so that the "inline" values can
|
|
still be rendered, rather than attempting to pass the values
|
|
as bound parameters.
|
|
|
|
.. versionadded:: 0.6.4 :meth:`.Operations.inline_literal` can now
|
|
be used with :meth:`.Operations.bulk_insert`, and the
|
|
:paramref:`~.Operations.bulk_insert.multiinsert` flag has
|
|
been added to assist in this usage when running in "online"
|
|
mode.
|
|
|
|
:param table: a table object which represents the target of the INSERT.
|
|
|
|
:param rows: a list of dictionaries indicating rows.
|
|
|
|
:param multiinsert: when at its default of True and --sql mode is not
|
|
enabled, the INSERT statement will be executed using
|
|
"executemany()" style, where all elements in the list of dictionaries
|
|
are passed as bound parameters in a single list. Setting this
|
|
to False results in individual INSERT statements being emitted
|
|
per parameter set, and is needed in those cases where non-literal
|
|
values are present in the parameter sets.
|
|
|
|
.. versionadded:: 0.6.4
|
|
|
|
"""
|
|
self.impl.bulk_insert(table, rows, multiinsert=multiinsert)
|
|
|
|
def inline_literal(self, value, type_=None):
|
|
"""Produce an 'inline literal' expression, suitable for
|
|
using in an INSERT, UPDATE, or DELETE statement.
|
|
|
|
When using Alembic in "offline" mode, CRUD operations
|
|
aren't compatible with SQLAlchemy's default behavior surrounding
|
|
literal values,
|
|
which is that they are converted into bound values and passed
|
|
separately into the ``execute()`` method of the DBAPI cursor.
|
|
An offline SQL
|
|
script needs to have these rendered inline. While it should
|
|
always be noted that inline literal values are an **enormous**
|
|
security hole in an application that handles untrusted input,
|
|
a schema migration is not run in this context, so
|
|
literals are safe to render inline, with the caveat that
|
|
advanced types like dates may not be supported directly
|
|
by SQLAlchemy.
|
|
|
|
See :meth:`.execute` for an example usage of
|
|
:meth:`.inline_literal`.
|
|
|
|
:param value: The value to render. Strings, integers, and simple
|
|
numerics should be supported. Other types like boolean,
|
|
dates, etc. may or may not be supported yet by various
|
|
backends.
|
|
:param ``type_``: optional - a :class:`sqlalchemy.types.TypeEngine`
|
|
subclass stating the type of this value. In SQLAlchemy
|
|
expressions, this is usually derived automatically
|
|
from the Python type of the value itself, as well as
|
|
based on the context in which the value is used.
|
|
|
|
"""
|
|
return impl._literal_bindparam(None, value, type_=type_)
|
|
|
|
def execute(self, sql, execution_options=None):
|
|
"""Execute the given SQL using the current migration context.
|
|
|
|
In a SQL script context, the statement is emitted directly to the
|
|
output stream. There is *no* return result, however, as this
|
|
function is oriented towards generating a change script
|
|
that can run in "offline" mode. For full interaction
|
|
with a connected database, use the "bind" available
|
|
from the context::
|
|
|
|
from alembic import op
|
|
connection = op.get_bind()
|
|
|
|
Also note that any parameterized statement here *will not work*
|
|
in offline mode - INSERT, UPDATE and DELETE statements which refer
|
|
to literal values would need to render
|
|
inline expressions. For simple use cases, the
|
|
:meth:`.inline_literal` function can be used for **rudimentary**
|
|
quoting of string values. For "bulk" inserts, consider using
|
|
:meth:`.bulk_insert`.
|
|
|
|
For example, to emit an UPDATE statement which is equally
|
|
compatible with both online and offline mode::
|
|
|
|
from sqlalchemy.sql import table, column
|
|
from sqlalchemy import String
|
|
from alembic import op
|
|
|
|
account = table('account',
|
|
column('name', String)
|
|
)
|
|
op.execute(
|
|
account.update().\\
|
|
where(account.c.name==op.inline_literal('account 1')).\\
|
|
values({'name':op.inline_literal('account 2')})
|
|
)
|
|
|
|
Note above we also used the SQLAlchemy
|
|
:func:`sqlalchemy.sql.expression.table`
|
|
and :func:`sqlalchemy.sql.expression.column` constructs to make a brief,
|
|
ad-hoc table construct just for our UPDATE statement. A full
|
|
:class:`~sqlalchemy.schema.Table` construct of course works perfectly
|
|
fine as well, though note it's a recommended practice to at least ensure
|
|
the definition of a table is self-contained within the migration script,
|
|
rather than imported from a module that may break compatibility with
|
|
older migrations.
|
|
|
|
:param sql: Any legal SQLAlchemy expression, including:
|
|
|
|
* a string
|
|
* a :func:`sqlalchemy.sql.expression.text` construct.
|
|
* a :func:`sqlalchemy.sql.expression.insert` construct.
|
|
* a :func:`sqlalchemy.sql.expression.update`,
|
|
:func:`sqlalchemy.sql.expression.insert`,
|
|
or :func:`sqlalchemy.sql.expression.delete` construct.
|
|
* Pretty much anything that's "executable" as described
|
|
in :ref:`sqlexpression_toplevel`.
|
|
|
|
:param execution_options: Optional dictionary of
|
|
execution options, will be passed to
|
|
:meth:`sqlalchemy.engine.Connection.execution_options`.
|
|
"""
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|
self.migration_context.impl.execute(sql,
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|
execution_options=execution_options)
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|
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|
def get_bind(self):
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"""Return the current 'bind'.
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|
|
|
Under normal circumstances, this is the
|
|
:class:`~sqlalchemy.engine.Connection` currently being used
|
|
to emit SQL to the database.
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|
|
|
In a SQL script context, this value is ``None``. [TODO: verify this]
|
|
|
|
"""
|
|
return self.migration_context.impl.bind
|
|
|