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Code Issues 32 Releases Wiki Activity

Fixed #28816 -- Prevented silencing data loss when decreasing CharField.max_length on PostgreSQL.

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This commit is contained in:
Hasan Ramezani
2019-05-11 17:29:24 +02:00
committed by Mariusz Felisiak
parent 519016e5f2
commit 1378d665a1
2 changed files with 26 additions and 3 deletions
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13
django/db/backends/postgresql/schema.py
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@@ -6,8 +6,6 @@ from django.db.backends.ddl_references import IndexColumns
class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
sql_alter_column_type = "ALTER COLUMN %(column)s TYPE %(type)s USING %(column)s::%(type)s"
sql_create_sequence = "CREATE SEQUENCE %(sequence)s"
sql_delete_sequence = "DROP SEQUENCE IF EXISTS %(sequence)s CASCADE"
sql_set_sequence_max = "SELECT setval('%(sequence)s', MAX(%(column)s)) FROM %(table)s"
@@ -36,6 +34,11 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
output.append(like_index_statement)
return output
def _field_data_type(self, field):
if field.is_relation:
return field.rel_db_type(self.connection)
return self.connection.data_types[field.get_internal_type()]
def _create_like_index_sql(self, model, field):
"""
Return the statement to create an index with varchar operator pattern
@@ -59,7 +62,11 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
return None
def _alter_column_type_sql(self, model, old_field, new_field, new_type):
"""Make ALTER TYPE with SERIAL make sense."""
self.sql_alter_column_type = 'ALTER COLUMN %(column)s TYPE %(type)s'
# Cast when data type changed.
if self._field_data_type(old_field) != self._field_data_type(new_field):
self.sql_alter_column_type += ' USING %(column)s::%(type)s'
# Make ALTER TYPE with SERIAL make sense.
table = model._meta.db_table
if new_type.lower() in ("serial", "bigserial"):
column = new_field.column