280 lines
10 KiB
Python
280 lines
10 KiB
Python
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from sqlalchemy.sql.expression import _BindParamClause
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from sqlalchemy.ext.compiler import compiles
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from sqlalchemy import schema, text
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from sqlalchemy import types as sqltypes
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from ..compat import string_types, text_type, with_metaclass
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from .. import util
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from . import base
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class ImplMeta(type):
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def __init__(cls, classname, bases, dict_):
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newtype = type.__init__(cls, classname, bases, dict_)
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if '__dialect__' in dict_:
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_impls[dict_['__dialect__']] = cls
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return newtype
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_impls = {}
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class DefaultImpl(with_metaclass(ImplMeta)):
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"""Provide the entrypoint for major migration operations,
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including database-specific behavioral variances.
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While individual SQL/DDL constructs already provide
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for database-specific implementations, variances here
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allow for entirely different sequences of operations
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to take place for a particular migration, such as
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SQL Server's special 'IDENTITY INSERT' step for
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bulk inserts.
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"""
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__dialect__ = 'default'
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transactional_ddl = False
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command_terminator = ";"
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def __init__(self, dialect, connection, as_sql,
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transactional_ddl, output_buffer,
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context_opts):
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self.dialect = dialect
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self.connection = connection
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self.as_sql = as_sql
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self.output_buffer = output_buffer
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self.memo = {}
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self.context_opts = context_opts
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if transactional_ddl is not None:
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self.transactional_ddl = transactional_ddl
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@classmethod
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def get_by_dialect(cls, dialect):
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return _impls[dialect.name]
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def static_output(self, text):
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self.output_buffer.write(text_type(text + "\n\n"))
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self.output_buffer.flush()
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@property
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def bind(self):
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return self.connection
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def _exec(self, construct, execution_options=None,
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multiparams=(),
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params=util.immutabledict()):
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if isinstance(construct, string_types):
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construct = text(construct)
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if self.as_sql:
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if multiparams or params:
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# TODO: coverage
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raise Exception("Execution arguments not allowed with as_sql")
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self.static_output(text_type(
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construct.compile(dialect=self.dialect)
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).replace("\t", " ").strip() + self.command_terminator)
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else:
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conn = self.connection
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if execution_options:
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conn = conn.execution_options(**execution_options)
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conn.execute(construct, *multiparams, **params)
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def execute(self, sql, execution_options=None):
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self._exec(sql, execution_options)
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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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name=None,
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type_=None,
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schema=None,
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autoincrement=None,
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existing_type=None,
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existing_server_default=None,
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existing_nullable=None,
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existing_autoincrement=None
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):
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if autoincrement is not None or existing_autoincrement is not None:
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util.warn("nautoincrement and existing_autoincrement only make sense for MySQL")
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if nullable is not None:
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self._exec(base.ColumnNullable(table_name, column_name,
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nullable, schema=schema,
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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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))
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if server_default is not False:
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self._exec(base.ColumnDefault(
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table_name, column_name, server_default,
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schema=schema,
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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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))
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if type_ is not None:
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self._exec(base.ColumnType(
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table_name, column_name, type_, schema=schema,
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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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))
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# do the new name last ;)
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if name is not None:
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self._exec(base.ColumnName(
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table_name, column_name, name, schema=schema,
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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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))
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def add_column(self, table_name, column, schema=None):
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self._exec(base.AddColumn(table_name, column, schema=schema))
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def drop_column(self, table_name, column, schema=None, **kw):
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self._exec(base.DropColumn(table_name, column, schema=schema))
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def add_constraint(self, const):
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if const._create_rule is None or \
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const._create_rule(self):
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self._exec(schema.AddConstraint(const))
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def drop_constraint(self, const):
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self._exec(schema.DropConstraint(const))
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def rename_table(self, old_table_name, new_table_name, schema=None):
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self._exec(base.RenameTable(old_table_name,
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new_table_name, schema=schema))
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def create_table(self, table):
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if util.sqla_07:
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table.dispatch.before_create(table, self.connection,
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checkfirst=False,
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_ddl_runner=self)
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self._exec(schema.CreateTable(table))
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if util.sqla_07:
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table.dispatch.after_create(table, self.connection,
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checkfirst=False,
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_ddl_runner=self)
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for index in table.indexes:
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self._exec(schema.CreateIndex(index))
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def drop_table(self, table):
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self._exec(schema.DropTable(table))
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def create_index(self, index):
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self._exec(schema.CreateIndex(index))
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def drop_index(self, index):
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self._exec(schema.DropIndex(index))
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def bulk_insert(self, table, rows, multiinsert=True):
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if not isinstance(rows, list):
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raise TypeError("List expected")
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elif rows and not isinstance(rows[0], dict):
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raise TypeError("List of dictionaries expected")
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if self.as_sql:
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for row in rows:
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self._exec(table.insert(inline=True).values(**dict(
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(k,
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_literal_bindparam(k, v, type_=table.c[k].type)
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if not isinstance(v, _literal_bindparam) else v)
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for k, v in row.items()
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)))
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else:
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# work around http://www.sqlalchemy.org/trac/ticket/2461
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if not hasattr(table, '_autoincrement_column'):
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table._autoincrement_column = None
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if rows:
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if multiinsert:
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self._exec(table.insert(inline=True), multiparams=rows)
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else:
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for row in rows:
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self._exec(table.insert(inline=True).values(**row))
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def compare_type(self, inspector_column, metadata_column):
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conn_type = inspector_column.type
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metadata_type = metadata_column.type
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metadata_impl = metadata_type.dialect_impl(self.dialect)
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# work around SQLAlchemy bug "stale value for type affinity"
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# fixed in 0.7.4
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metadata_impl.__dict__.pop('_type_affinity', None)
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if conn_type._compare_type_affinity(
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metadata_impl
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):
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comparator = _type_comparators.get(conn_type._type_affinity, None)
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return comparator and comparator(metadata_type, conn_type)
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else:
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return True
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def compare_server_default(self, inspector_column,
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metadata_column,
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rendered_metadata_default,
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rendered_inspector_default):
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return rendered_inspector_default != rendered_metadata_default
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def correct_for_autogen_constraints(self, conn_uniques, conn_indexes,
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metadata_unique_constraints,
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metadata_indexes):
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pass
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def start_migrations(self):
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"""A hook called when :meth:`.EnvironmentContext.run_migrations`
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is called.
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Implementations can set up per-migration-run state here.
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"""
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def emit_begin(self):
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"""Emit the string ``BEGIN``, or the backend-specific
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equivalent, on the current connection context.
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This is used in offline mode and typically
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via :meth:`.EnvironmentContext.begin_transaction`.
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"""
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self.static_output("BEGIN" + self.command_terminator)
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def emit_commit(self):
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"""Emit the string ``COMMIT``, or the backend-specific
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equivalent, on the current connection context.
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This is used in offline mode and typically
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via :meth:`.EnvironmentContext.begin_transaction`.
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"""
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self.static_output("COMMIT" + self.command_terminator)
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class _literal_bindparam(_BindParamClause):
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pass
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@compiles(_literal_bindparam)
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def _render_literal_bindparam(element, compiler, **kw):
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return compiler.render_literal_bindparam(element, **kw)
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def _string_compare(t1, t2):
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return \
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t1.length is not None and \
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t1.length != t2.length
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def _numeric_compare(t1, t2):
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return \
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(
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t1.precision is not None and \
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t1.precision != t2.precision
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) or \
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(
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t1.scale is not None and \
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t1.scale != t2.scale
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)
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_type_comparators = {
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sqltypes.String:_string_compare,
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sqltypes.Numeric:_numeric_compare
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}
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