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