74 lines
2.8 KiB
Python
74 lines
2.8 KiB
Python
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from .. import util
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from .impl import DefaultImpl
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#from sqlalchemy.ext.compiler import compiles
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#from .base import AddColumn, alter_table
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#from sqlalchemy.schema import AddConstraint
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class SQLiteImpl(DefaultImpl):
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__dialect__ = 'sqlite'
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transactional_ddl = False
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"""SQLite supports transactional DDL, but pysqlite does not:
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see: http://bugs.python.org/issue10740
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"""
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def add_constraint(self, const):
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# attempt to distinguish between an
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# auto-gen constraint and an explicit one
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if const._create_rule is None:
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raise NotImplementedError(
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"No support for ALTER of constraints in SQLite dialect")
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elif const._create_rule(self):
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util.warn("Skipping unsupported ALTER for "
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"creation of implicit constraint")
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def drop_constraint(self, const):
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if const._create_rule is None:
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raise NotImplementedError(
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"No support for ALTER of constraints in SQLite dialect")
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def correct_for_autogen_constraints(self, conn_unique_constraints, conn_indexes,
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metadata_unique_constraints,
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metadata_indexes):
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def uq_sig(uq):
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return tuple(sorted(uq.columns.keys()))
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conn_unique_sigs = set(
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uq_sig(uq)
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for uq in conn_unique_constraints
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)
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for idx in list(metadata_unique_constraints):
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# SQLite backend can't report on unnamed UNIQUE constraints,
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# so remove these, unless we see an exact signature match
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if idx.name is None and uq_sig(idx) not in conn_unique_sigs:
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metadata_unique_constraints.remove(idx)
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for idx in list(conn_unique_constraints):
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# just in case we fix the backend such that it does report
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# on them, blow them out of the reflected collection too otherwise
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# they will come up as removed. if the backend supports this now,
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# add a version check here for the dialect.
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if idx.name is None:
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conn_uniques.remove(idx)
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#@compiles(AddColumn, 'sqlite')
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#def visit_add_column(element, compiler, **kw):
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# return "%s %s" % (
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# alter_table(compiler, element.table_name, element.schema),
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# add_column(compiler, element.column, **kw)
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# )
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#def add_column(compiler, column, **kw):
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# text = "ADD COLUMN %s" % compiler.get_column_specification(column, **kw)
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# # need to modify SQLAlchemy so that the CHECK associated with a Boolean
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# # or Enum gets placed as part of the column constraints, not the Table
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# # see ticket 98
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# for const in column.constraints:
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# text += compiler.process(AddConstraint(const))
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# return text
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