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Refs #25002 -- Supported textual to temporal column alteration on Oracle. 

Thanks to Tim Graham for the report and Shai Berger for the review.
This commit is contained in:
Simon Charette 2015-06-22 23:53:49 -04:00
parent aaacaeb096
commit bdb382b2a4
2 changed files with 65 additions and 15 deletions
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39
django/db/backends/oracle/schema.py
View File

@ -1,6 +1,7 @@
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):
"""

41
tests/schema/tests.py
View File

@ -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):