244 lines
9.4 KiB
Python
244 lines
9.4 KiB
Python
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from django.db.backends.base.schema import BaseDatabaseSchemaEditor
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from django.db.models import NOT_PROVIDED, F, UniqueConstraint
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from django.db.models.constants import LOOKUP_SEP
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class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
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sql_rename_table = "RENAME TABLE %(old_table)s TO %(new_table)s"
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sql_alter_column_null = "MODIFY %(column)s %(type)s NULL"
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sql_alter_column_not_null = "MODIFY %(column)s %(type)s NOT NULL"
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sql_alter_column_type = "MODIFY %(column)s %(type)s%(collation)s%(comment)s"
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sql_alter_column_no_default_null = "ALTER COLUMN %(column)s SET DEFAULT NULL"
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# No 'CASCADE' which works as a no-op in MySQL but is undocumented
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sql_delete_column = "ALTER TABLE %(table)s DROP COLUMN %(column)s"
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sql_delete_unique = "ALTER TABLE %(table)s DROP INDEX %(name)s"
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sql_create_column_inline_fk = (
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", ADD CONSTRAINT %(name)s FOREIGN KEY (%(column)s) "
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"REFERENCES %(to_table)s(%(to_column)s)"
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)
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sql_delete_fk = "ALTER TABLE %(table)s DROP FOREIGN KEY %(name)s"
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sql_delete_index = "DROP INDEX %(name)s ON %(table)s"
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sql_rename_index = "ALTER TABLE %(table)s RENAME INDEX %(old_name)s TO %(new_name)s"
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sql_create_pk = (
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"ALTER TABLE %(table)s ADD CONSTRAINT %(name)s PRIMARY KEY (%(columns)s)"
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)
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sql_delete_pk = "ALTER TABLE %(table)s DROP PRIMARY KEY"
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sql_create_index = "CREATE INDEX %(name)s ON %(table)s (%(columns)s)%(extra)s"
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sql_alter_table_comment = "ALTER TABLE %(table)s COMMENT = %(comment)s"
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sql_alter_column_comment = None
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@property
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def sql_delete_check(self):
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if self.connection.mysql_is_mariadb:
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# The name of the column check constraint is the same as the field
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# name on MariaDB. Adding IF EXISTS clause prevents migrations
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# crash. Constraint is removed during a "MODIFY" column statement.
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return "ALTER TABLE %(table)s DROP CONSTRAINT IF EXISTS %(name)s"
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return "ALTER TABLE %(table)s DROP CHECK %(name)s"
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@property
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def sql_rename_column(self):
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# MariaDB >= 10.5.2 and MySQL >= 8.0.4 support an
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# "ALTER TABLE ... RENAME COLUMN" statement.
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if self.connection.mysql_is_mariadb:
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if self.connection.mysql_version >= (10, 5, 2):
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return super().sql_rename_column
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elif self.connection.mysql_version >= (8, 0, 4):
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return super().sql_rename_column
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return "ALTER TABLE %(table)s CHANGE %(old_column)s %(new_column)s %(type)s"
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def quote_value(self, value):
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self.connection.ensure_connection()
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if isinstance(value, str):
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value = value.replace("%", "%%")
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# MySQLdb escapes to string, PyMySQL to bytes.
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quoted = self.connection.connection.escape(
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value, self.connection.connection.encoders
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)
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if isinstance(value, str) and isinstance(quoted, bytes):
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quoted = quoted.decode()
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return quoted
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def _is_limited_data_type(self, field):
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db_type = field.db_type(self.connection)
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return (
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db_type is not None
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and db_type.lower() in self.connection._limited_data_types
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)
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def skip_default(self, field):
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if not self._supports_limited_data_type_defaults:
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return self._is_limited_data_type(field)
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return False
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def skip_default_on_alter(self, field):
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if self._is_limited_data_type(field) and not self.connection.mysql_is_mariadb:
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# MySQL doesn't support defaults for BLOB and TEXT in the
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# ALTER COLUMN statement.
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return True
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return False
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@property
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def _supports_limited_data_type_defaults(self):
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# MariaDB and MySQL >= 8.0.13 support defaults for BLOB and TEXT.
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if self.connection.mysql_is_mariadb:
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return True
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return self.connection.mysql_version >= (8, 0, 13)
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def _column_default_sql(self, field):
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if (
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not self.connection.mysql_is_mariadb
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and self._supports_limited_data_type_defaults
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and self._is_limited_data_type(field)
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):
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# MySQL supports defaults for BLOB and TEXT columns only if the
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# default value is written as an expression i.e. in parentheses.
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return "(%s)"
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return super()._column_default_sql(field)
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def add_field(self, model, field):
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super().add_field(model, field)
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# Simulate the effect of a one-off default.
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# field.default may be unhashable, so a set isn't used for "in" check.
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if self.skip_default(field) and field.default not in (None, NOT_PROVIDED):
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effective_default = self.effective_default(field)
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self.execute(
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"UPDATE %(table)s SET %(column)s = %%s"
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% {
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"table": self.quote_name(model._meta.db_table),
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"column": self.quote_name(field.column),
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},
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[effective_default],
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)
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def remove_constraint(self, model, constraint):
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if (
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isinstance(constraint, UniqueConstraint)
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and constraint.create_sql(model, self) is not None
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):
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self._create_missing_fk_index(
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model,
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fields=constraint.fields,
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expressions=constraint.expressions,
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)
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super().remove_constraint(model, constraint)
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def remove_index(self, model, index):
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self._create_missing_fk_index(
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model,
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fields=[field_name for field_name, _ in index.fields_orders],
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expressions=index.expressions,
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)
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super().remove_index(model, index)
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def _field_should_be_indexed(self, model, field):
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if not super()._field_should_be_indexed(model, field):
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return False
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storage = self.connection.introspection.get_storage_engine(
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self.connection.cursor(), model._meta.db_table
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)
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# No need to create an index for ForeignKey fields except if
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# db_constraint=False because the index from that constraint won't be
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# created.
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if (
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storage == "InnoDB"
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and field.get_internal_type() == "ForeignKey"
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and field.db_constraint
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):
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return False
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return not self._is_limited_data_type(field)
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def _create_missing_fk_index(
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self,
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model,
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*,
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fields,
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expressions=None,
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):
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"""
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MySQL can remove an implicit FK index on a field when that field is
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covered by another index like a unique_together. "covered" here means
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that the more complex index has the FK field as its first field (see
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https://bugs.mysql.com/bug.php?id=37910).
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Manually create an implicit FK index to make it possible to remove the
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composed index.
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"""
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first_field_name = None
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if fields:
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first_field_name = fields[0]
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elif (
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expressions
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and self.connection.features.supports_expression_indexes
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and isinstance(expressions[0], F)
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and LOOKUP_SEP not in expressions[0].name
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):
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first_field_name = expressions[0].name
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if not first_field_name:
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return
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first_field = model._meta.get_field(first_field_name)
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if first_field.get_internal_type() == "ForeignKey":
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column = self.connection.introspection.identifier_converter(
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first_field.column
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)
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with self.connection.cursor() as cursor:
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constraint_names = [
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name
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for name, infodict in self.connection.introspection.get_constraints(
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cursor, model._meta.db_table
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).items()
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if infodict["index"] and infodict["columns"][0] == column
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]
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# There are no other indexes that starts with the FK field, only
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# the index that is expected to be deleted.
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if len(constraint_names) == 1:
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self.execute(
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self._create_index_sql(model, fields=[first_field], suffix="")
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)
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def _delete_composed_index(self, model, fields, *args):
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self._create_missing_fk_index(model, fields=fields)
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return super()._delete_composed_index(model, fields, *args)
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def _set_field_new_type_null_status(self, field, new_type):
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"""
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Keep the null property of the old field. If it has changed, it will be
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handled separately.
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"""
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if field.null:
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new_type += " NULL"
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else:
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new_type += " NOT NULL"
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return new_type
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def _alter_column_type_sql(
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self, model, old_field, new_field, new_type, old_collation, new_collation
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):
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new_type = self._set_field_new_type_null_status(old_field, new_type)
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return super()._alter_column_type_sql(
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model, old_field, new_field, new_type, old_collation, new_collation
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)
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def _rename_field_sql(self, table, old_field, new_field, new_type):
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new_type = self._set_field_new_type_null_status(old_field, new_type)
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return super()._rename_field_sql(table, old_field, new_field, new_type)
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def _alter_column_comment_sql(self, model, new_field, new_type, new_db_comment):
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# Comment is alter when altering the column type.
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return "", []
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def _comment_sql(self, comment):
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comment_sql = super()._comment_sql(comment)
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return f" COMMENT {comment_sql}"
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