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Fixed #31399 -- Made SchemaEditor._alter_field() ignore foreign key constraints if unsupported.

This commit is contained in:
Tim Graham 2020-03-24 20:21:14 -04:00 committed by Mariusz Felisiak
parent f344c75fb0
commit 8bebb8f126
1 changed files with 7 additions and 3 deletions
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10
django/db/backends/base/schema.py
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@ -569,7 +569,11 @@ class BaseDatabaseSchemaEditor:
"""Perform a "physical" (non-ManyToMany) field update."""
# Drop any FK constraints, we'll remake them later
fks_dropped = set()
if old_field.remote_field and old_field.db_constraint:
if (
self.connection.features.supports_foreign_keys and
old_field.remote_field and
old_field.db_constraint
):
fk_names = self._constraint_names(model, [old_field.column], foreign_key=True)
if strict and len(fk_names) != 1:
raise ValueError("Found wrong number (%s) of foreign key constraints for %s.%s" % (
@ -599,7 +603,7 @@ class BaseDatabaseSchemaEditor:
# Drop incoming FK constraints if the field is a primary key or unique,
# which might be a to_field target, and things are going to change.
drop_foreign_keys = (
(
self.connection.features.supports_foreign_keys and (
(old_field.primary_key and new_field.primary_key) or
(old_field.unique and new_field.unique)
) and old_type != new_type
@ -782,7 +786,7 @@ class BaseDatabaseSchemaEditor:
for sql, params in other_actions:
self.execute(sql, params)
# Does it have a foreign key?
if (new_field.remote_field and
if (self.connection.features.supports_foreign_keys and new_field.remote_field and
(fks_dropped or not old_field.remote_field or not old_field.db_constraint) and
new_field.db_constraint):
self.execute(self._create_fk_sql(model, new_field, "_fk_%(to_table)s_%(to_column)s"))