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Code Issues 32 Releases Wiki Activity

Fixed #23844 -- Used topological sort for migration operation dependency resolution.

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This removes the concept of equality between operations to guarantee
compatilibity with Python 3.

Python 3 requires equality to result in identical object hashes. It's
impossible to implement a unique hash that preserves equality as
operations such as field creation depend on being able to accept
arbitrary dicts that cannot be hashed reliably.

Thanks Klaas van Schelven for the original patch in
13d613f800.
This commit is contained in:
Patryk Zawadzki
2014-11-15 20:25:43 +01:00
committed by Tim Graham
parent 53908c1f93
commit 21e21c7bc2
11 changed files with 197 additions and 88 deletions
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35
tests/migrations/test_optimizer.py
View File

@@ -20,43 +20,14 @@ class OptimizerTests(TestCase):
def assertOptimizesTo(self, operations, expected, exact=None, less_than=None):
result, iterations = self.optimize(operations)
result = [repr(f.deconstruct()) for f in result]
expected = [repr(f.deconstruct()) for f in expected]
self.assertEqual(expected, result)
if exact is not None and iterations != exact:
raise self.failureException("Optimization did not take exactly %s iterations (it took %s)" % (exact, iterations))
if less_than is not None and iterations >= less_than:
raise self.failureException("Optimization did not take less than %s iterations (it took %s)" % (less_than, iterations))
def test_operation_equality(self):
"""
Tests the equality operator on lists of operations.
If this is broken, then the optimizer will get stuck in an
infinite loop, so it's kind of important.
"""
self.assertEqual(
[migrations.DeleteModel("Test")],
[migrations.DeleteModel("Test")],
)
self.assertEqual(
[migrations.CreateModel("Test", [("name", models.CharField(max_length=255))])],
[migrations.CreateModel("Test", [("name", models.CharField(max_length=255))])],
)
self.assertNotEqual(
[migrations.CreateModel("Test", [("name", models.CharField(max_length=255))])],
[migrations.CreateModel("Test", [("name", models.CharField(max_length=100))])],
)
self.assertEqual(
[migrations.AddField("Test", "name", models.CharField(max_length=255))],
[migrations.AddField("Test", "name", models.CharField(max_length=255))],
)
self.assertNotEqual(
[migrations.AddField("Test", "name", models.CharField(max_length=255))],
[migrations.AddField("Test", "name", models.CharField(max_length=100))],
)
self.assertNotEqual(
[migrations.AddField("Test", "name", models.CharField(max_length=255))],
[migrations.AlterField("Test", "name", models.CharField(max_length=255))],
)
def test_single(self):
"""
Tests that the optimizer does nothing on a single operation,
@@ -331,7 +302,7 @@ class OptimizerTests(TestCase):
migrations.AlterField("Foo", "age", models.FloatField(default=2.4)),
],
[
migrations.AddField("Foo", "age", models.FloatField(default=2.4)),
migrations.AddField("Foo", name="age", field=models.FloatField(default=2.4)),
],
)