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Add an Executor for end-to-end running
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68
django/db/migrations/executor.py
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68
django/db/migrations/executor.py
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@ -0,0 +1,68 @@
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from .loader import MigrationLoader
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from .recorder import MigrationRecorder
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class MigrationExecutor(object):
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"""
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End-to-end migration execution - loads migrations, and runs them
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up or down to a specified set of targets.
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"""
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def __init__(self, connection):
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self.connection = connection
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self.loader = MigrationLoader(self.connection)
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self.recorder = MigrationRecorder(self.connection)
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def migration_plan(self, targets):
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"""
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Given a set of targets, returns a list of (Migration instance, backwards?).
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"""
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plan = []
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applied = self.recorder.applied_migrations()
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for target in targets:
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# If the migration is already applied, do backwards mode,
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# otherwise do forwards mode.
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if target in applied:
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for migration in self.loader.graph.backwards_plan(target)[:-1]:
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if migration in applied:
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plan.append((self.loader.graph.nodes[migration], True))
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applied.remove(migration)
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else:
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for migration in self.loader.graph.forwards_plan(target):
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if migration not in applied:
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plan.append((self.loader.graph.nodes[migration], False))
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applied.add(migration)
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return plan
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def migrate(self, targets):
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"""
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Migrates the database up to the given targets.
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"""
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plan = self.migration_plan(targets)
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for migration, backwards in plan:
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if not backwards:
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self.apply_migration(migration)
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else:
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self.unapply_migration(migration)
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def apply_migration(self, migration):
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"""
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Runs a migration forwards.
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"""
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print "Applying %s" % migration
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with self.connection.schema_editor() as schema_editor:
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project_state = self.loader.graph.project_state((migration.app_label, migration.name), at_end=False)
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migration.apply(project_state, schema_editor)
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self.recorder.record_applied(migration.app_label, migration.name)
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print "Finished %s" % migration
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def unapply_migration(self, migration):
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"""
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Runs a migration backwards.
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"""
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print "Unapplying %s" % migration
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with self.connection.schema_editor() as schema_editor:
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project_state = self.loader.graph.project_state((migration.app_label, migration.name), at_end=False)
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migration.unapply(project_state, schema_editor)
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self.recorder.record_unapplied(migration.app_label, migration.name)
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print "Finished %s" % migration
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@ -36,6 +36,17 @@ class Migration(object):
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self.name = name
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self.app_label = app_label
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def __eq__(self, other):
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if not isinstance(other, Migration):
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return False
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return (self.name == other.name) and (self.app_label == other.app_label)
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def __ne__(self, other):
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return not (self == other)
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def __repr__(self):
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return "<Migration %s.%s>" % (self.app_label, self.name)
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def mutate_state(self, project_state):
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"""
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Takes a ProjectState and returns a new one with the migration's
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@ -45,3 +56,40 @@ class Migration(object):
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for operation in self.operations:
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operation.state_forwards(self.app_label, new_state)
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return new_state
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def apply(self, project_state, schema_editor):
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"""
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Takes a project_state representing all migrations prior to this one
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and a schema_editor for a live database and applies the migration
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in a forwards order.
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Returns the resulting project state for efficient re-use by following
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Migrations.
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"""
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for operation in self.operations:
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# Get the state after the operation has run
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new_state = project_state.clone()
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operation.state_forwards(self.app_label, new_state)
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# Run the operation
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operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
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# Switch states
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project_state = new_state
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return project_state
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def unapply(self, project_state, schema_editor):
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"""
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Takes a project_state representing all migrations prior to this one
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and a schema_editor for a live database and applies the migration
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in a reverse order.
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"""
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# We need to pre-calculate the stack of project states
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to_run = []
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for operation in self.operations:
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new_state = project_state.clone()
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operation.state_forwards(self.app_label, new_state)
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to_run.append((operation, project_state, new_state))
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project_state = new_state
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# Now run them in reverse
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to_run.reverse()
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for operation, to_state, from_state in to_run:
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operation.database_backwards(self.app_label, schema_editor, from_state, to_state)
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@ -16,13 +16,13 @@ class AddField(Operation):
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def database_forwards(self, app_label, schema_editor, from_state, to_state):
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app_cache = to_state.render()
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model = app_cache.get_model(app_label, self.name)
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schema_editor.add_field(model, model._meta.get_field_by_name(self.name))
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model = app_cache.get_model(app_label, self.model_name)
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schema_editor.add_field(model, model._meta.get_field_by_name(self.name)[0])
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def database_backwards(self, app_label, schema_editor, from_state, to_state):
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app_cache = from_state.render()
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model = app_cache.get_model(app_label, self.name)
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schema_editor.remove_field(model, model._meta.get_field_by_name(self.name))
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model = app_cache.get_model(app_label, self.model_name)
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schema_editor.remove_field(model, model._meta.get_field_by_name(self.name)[0])
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class RemoveField(Operation):
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@ -43,10 +43,10 @@ class RemoveField(Operation):
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def database_forwards(self, app_label, schema_editor, from_state, to_state):
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app_cache = from_state.render()
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model = app_cache.get_model(app_label, self.name)
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schema_editor.remove_field(model, model._meta.get_field_by_name(self.name))
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model = app_cache.get_model(app_label, self.model_name)
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schema_editor.remove_field(model, model._meta.get_field_by_name(self.name)[0])
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def database_backwards(self, app_label, schema_editor, from_state, to_state):
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app_cache = to_state.render()
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model = app_cache.get_model(app_label, self.name)
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schema_editor.add_field(model, model._meta.get_field_by_name(self.name))
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model = app_cache.get_model(app_label, self.model_name)
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schema_editor.add_field(model, model._meta.get_field_by_name(self.name)[0])
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@ -11,7 +11,7 @@ class Migration(migrations.Migration):
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migrations.RemoveField("Author", "silly_field"),
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migrations.AddField("Author", "important", models.BooleanField()),
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migrations.AddField("Author", "rating", models.IntegerField(default=0)),
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migrations.CreateModel(
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"Book",
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35
tests/migrations/test_executor.py
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35
tests/migrations/test_executor.py
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@ -0,0 +1,35 @@
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from django.test import TransactionTestCase
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from django.db import connection
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from django.db.migrations.executor import MigrationExecutor
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class ExecutorTests(TransactionTestCase):
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"""
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Tests the migration executor (full end-to-end running).
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Bear in mind that if these are failing you should fix the other
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test failures first, as they may be propagating into here.
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"""
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def test_run(self):
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"""
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Tests running a simple set of migrations.
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"""
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executor = MigrationExecutor(connection)
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# Let's look at the plan first and make sure it's up to scratch
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plan = executor.migration_plan([("migrations", "0002_second")])
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self.assertEqual(
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plan,
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[
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(executor.loader.graph.nodes["migrations", "0001_initial"], False),
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(executor.loader.graph.nodes["migrations", "0002_second"], False),
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],
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)
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# Were the tables there before?
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self.assertNotIn("migrations_author", connection.introspection.get_table_list(connection.cursor()))
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self.assertNotIn("migrations_book", connection.introspection.get_table_list(connection.cursor()))
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# Alright, let's try running it
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executor.migrate([("migrations", "0002_second")])
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# Are the tables there now?
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self.assertIn("migrations_author", connection.introspection.get_table_list(connection.cursor()))
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self.assertIn("migrations_book", connection.introspection.get_table_list(connection.cursor()))
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@ -54,7 +54,7 @@ class LoaderTests(TransactionTestCase):
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author_state = project_state.models["migrations", "author"]
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self.assertEqual(
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[x for x, y in author_state.fields],
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["id", "name", "slug", "age", "important"]
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["id", "name", "slug", "age", "rating"]
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)
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book_state = project_state.models["migrations", "book"]
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from django.test import TransactionTestCase
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from django.db import connection, models, migrations
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from django.db.migrations.state import ProjectState, ModelState
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from django.db.migrations.state import ProjectState
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class OperationTests(TransactionTestCase):
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@ -16,6 +16,12 @@ class OperationTests(TransactionTestCase):
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def assertTableNotExists(self, table):
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self.assertNotIn(table, connection.introspection.get_table_list(connection.cursor()))
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def assertColumnExists(self, table, column):
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self.assertIn(column, [c.name for c in connection.introspection.get_table_description(connection.cursor(), table)])
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def assertColumnNotExists(self, table, column):
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self.assertNotIn(column, [c.name for c in connection.introspection.get_table_description(connection.cursor(), table)])
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def set_up_test_model(self, app_label):
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"""
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Creates a test model state and database table.
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@ -82,3 +88,23 @@ class OperationTests(TransactionTestCase):
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with connection.schema_editor() as editor:
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operation.database_backwards("test_dlmo", editor, new_state, project_state)
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self.assertTableExists("test_dlmo_pony")
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def test_add_field(self):
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"""
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Tests the AddField operation.
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"""
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project_state = self.set_up_test_model("test_adfl")
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# Test the state alteration
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operation = migrations.AddField("Pony", "height", models.FloatField(null=True))
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new_state = project_state.clone()
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operation.state_forwards("test_adfl", new_state)
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self.assertEqual(len(new_state.models["test_adfl", "pony"].fields), 3)
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# Test the database alteration
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self.assertColumnNotExists("test_adfl_pony", "height")
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with connection.schema_editor() as editor:
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operation.database_forwards("test_adfl", editor, project_state, new_state)
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self.assertColumnExists("test_adfl_pony", "height")
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# And test reversal
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with connection.schema_editor() as editor:
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operation.database_backwards("test_adfl", editor, new_state, project_state)
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self.assertColumnNotExists("test_adfl_pony", "height")
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