Refs #25002 -- Supported textual to temporal column alteration on Oracle. (bdb382b2) · Commits · Dom Sekotill / django

django/db/backends/oracle/schema.py

+27 −12

Original line number	Diff line number	Diff line
		import binascii
		import copy
		import datetime
		import re

		from django.db.backends.base.schema import BaseDatabaseSchemaEditor
		from django.db.utils import DatabaseError
		@@ -49,44 +50,58 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):

		def alter_field(self, model, old_field, new_field, strict=False):
		try:
		# Run superclass action
		super(DatabaseSchemaEditor, self).alter_field(model, old_field, new_field, strict)
		except DatabaseError as e:
		description = str(e)
		# If we're changing to/from LOB fields, we need to do a
		# If we're changing type to an unsupported type we need a
		# SQLite-ish workaround
		if 'ORA-22858' in description or 'ORA-22859' in description:
		self._alter_field_lob_workaround(model, old_field, new_field)
		self._alter_field_type_workaround(model, old_field, new_field)
		else:
		raise

		def _alter_field_lob_workaround(self, model, old_field, new_field):
		def _alter_field_type_workaround(self, model, old_field, new_field):
		"""
		Oracle refuses to change a column type from/to LOB to/from a regular
		column. In Django, this shows up when the field is changed from/to
		a TextField.
		Oracle refuses to change from some type to other type.
		What we need to do instead is:
		- Add the desired field with a temporary name
		- Add a nullable version of the desired field with a temporary name
		- Update the table to transfer values from old to new
		- Drop old column
		- Rename the new column
		- Rename the new column and possibly drop the nullable property
		"""
		# Make a new field that's like the new one but with a temporary
		# column name.
		new_temp_field = copy.deepcopy(new_field)
		new_temp_field.null = True
		new_temp_field.column = self._generate_temp_name(new_field.column)
		# Add it
		self.add_field(model, new_temp_field)
		# Explicit data type conversion
		# https://docs.oracle.com/cd/B19306_01/server.102/b14200/sql_elements002.htm#sthref340
		new_value = self.quote_name(old_field.column)
		old_type = old_field.db_type(self.connection)
		if re.match('^N?CLOB', old_type):
		new_value = "TO_CHAR(%s)" % new_value
		old_type = 'VARCHAR2'
		if re.match('^N?VARCHAR2', old_type):
		new_internal_type = new_field.get_internal_type()
		if new_internal_type == 'DateField':
		new_value = "TO_DATE(%s, 'YYYY-MM-DD')" % new_value
		elif new_internal_type == 'DateTimeField':
		new_value = "TO_TIMESTAMP(%s, 'YYYY-MM-DD HH24:MI:SS.FF')" % new_value
		elif new_internal_type == 'TimeField':
		# TimeField are stored as TIMESTAMP with a 1900-01-01 date part.
		new_value = "TO_TIMESTAMP(CONCAT('1900-01-01 ', %s), 'YYYY-MM-DD HH24:MI:SS.FF')" % new_value
		# Transfer values across
		self.execute("UPDATE %s set %s=%s" % (
		self.quote_name(model._meta.db_table),
		self.quote_name(new_temp_field.column),
		self.quote_name(old_field.column),
		new_value,
		))
		# Drop the old field
		self.remove_field(model, old_field)
		# Rename the new field
		self.alter_field(model, new_temp_field, new_field)
		# Rename and possibly make the new field NOT NULL
		super(DatabaseSchemaEditor, self).alter_field(model, new_temp_field, new_field)

		def normalize_name(self, name):
		"""

tests/schema/tests.py

+38 −3

Original line number	Diff line number	Diff line
		@@ -9,8 +9,8 @@ from django.db import (
		from django.db.models import Model
		from django.db.models.fields import (
		AutoField, BigIntegerField, BinaryField, BooleanField, CharField,
		DateTimeField, IntegerField, PositiveIntegerField, SlugField, TextField,
		TimeField,
		DateField, DateTimeField, IntegerField, PositiveIntegerField, SlugField,
		TextField, TimeField,
		)
		from django.db.models.fields.related import (
		ForeignKey, ManyToManyField, OneToOneField,
		@@ -448,18 +448,53 @@ class SchemaTests(TransactionTestCase):
		with connection.schema_editor() as editor:
		editor.alter_field(Note, old_field, new_field, strict=True)

		def test_alter_text_field_to_date_field(self):
		"""
		#25002 - Test conversion of text field to date field.
		"""
		with connection.schema_editor() as editor:
		editor.create_model(Note)
		Note.objects.create(info='1988-05-05')
		old_field = Note._meta.get_field('info')
		new_field = DateField(blank=True)
		new_field.set_attributes_from_name('info')
		with connection.schema_editor() as editor:
		editor.alter_field(Note, old_field, new_field, strict=True)
		# Make sure the field isn't nullable
		columns = self.column_classes(Note)
		self.assertFalse(columns['info'][1][6])

		def test_alter_text_field_to_datetime_field(self):
		"""
		#25002 - Test conversion of text field to datetime field.
		"""
		with connection.schema_editor() as editor:
		editor.create_model(Note)
		Note.objects.create(info='1988-05-05 3:16:17.4567')
		old_field = Note._meta.get_field('info')
		new_field = DateTimeField(blank=True)
		new_field.set_attributes_from_name('info')
		with connection.schema_editor() as editor:
		editor.alter_field(Note, old_field, new_field, strict=True)
		# Make sure the field isn't nullable
		columns = self.column_classes(Note)
		self.assertFalse(columns['info'][1][6])

		def test_alter_text_field_to_time_field(self):
		"""
		#25002 - Test conversion of text field to time field.
		"""
		with connection.schema_editor() as editor:
		editor.create_model(Note)
		Note.objects.create(info='3:16')
		Note.objects.create(info='3:16:17.4567')
		old_field = Note._meta.get_field('info')
		new_field = TimeField(blank=True)
		new_field.set_attributes_from_name('info')
		with connection.schema_editor() as editor:
		editor.alter_field(Note, old_field, new_field, strict=True)
		# Make sure the field isn't nullable
		columns = self.column_classes(Note)
		self.assertFalse(columns['info'][1][6])

		@skipIfDBFeature('interprets_empty_strings_as_nulls')
		def test_alter_textual_field_keep_null_status(self):