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Fixed #31392 -- Avoided unnecessary SchemaEditor.effective_default() calls when altering a field.

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Shipeng Feng 2020-03-24 20:09:43 +08:00 committed by GitHub
parent be648d1c45
commit 8fe2447a01
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1 changed files with 11 additions and 11 deletions
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22
django/db/backends/base/schema.py
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@ -675,17 +675,17 @@ class BaseDatabaseSchemaEditor:
# 3. Replace NULL constraint with NOT NULL # 3. Replace NULL constraint with NOT NULL
# 4. Drop the default again. # 4. Drop the default again.
# Default change? # Default change?
old_default = self.effective_default(old_field) needs_database_default = False
new_default = self.effective_default(new_field) if old_field.null and not new_field.null:
needs_database_default = ( old_default = self.effective_default(old_field)
old_field.null and new_default = self.effective_default(new_field)
not new_field.null and if (
old_default != new_default and not self.skip_default(new_field) and
new_default is not None and old_default != new_default and
not self.skip_default(new_field) new_default is not None
) ):
if needs_database_default: needs_database_default = True
actions.append(self._alter_column_default_sql(model, old_field, new_field)) actions.append(self._alter_column_default_sql(model, old_field, new_field))
# Nullability change? # Nullability change?
if old_field.null != new_field.null: if old_field.null != new_field.null:
fragment = self._alter_column_null_sql(model, old_field, new_field) fragment = self._alter_column_null_sql(model, old_field, new_field)