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Add an Executor for end-to-end running

This commit is contained in:
Andrew Godwin 2013-05-30 18:08:58 +01:00
parent 7f9a0b7061
commit e6f7f4533c
7 changed files with 188 additions and 11 deletions
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68
django/db/migrations/executor.py Normal file
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@ -0,0 +1,68 @@
from .loader import MigrationLoader
from .recorder import MigrationRecorder
class MigrationExecutor(object):
"""
End-to-end migration execution - loads migrations, and runs them
up or down to a specified set of targets.
"""
def __init__(self, connection):
self.connection = connection
self.loader = MigrationLoader(self.connection)
self.recorder = MigrationRecorder(self.connection)
def migration_plan(self, targets):
"""
Given a set of targets, returns a list of (Migration instance, backwards?).
"""
plan = []
applied = self.recorder.applied_migrations()
for target in targets:
# If the migration is already applied, do backwards mode,
# otherwise do forwards mode.
if target in applied:
for migration in self.loader.graph.backwards_plan(target)[:-1]:
if migration in applied:
plan.append((self.loader.graph.nodes[migration], True))
applied.remove(migration)
else:
for migration in self.loader.graph.forwards_plan(target):
if migration not in applied:
plan.append((self.loader.graph.nodes[migration], False))
applied.add(migration)
return plan
def migrate(self, targets):
"""
Migrates the database up to the given targets.
"""
plan = self.migration_plan(targets)
for migration, backwards in plan:
if not backwards:
self.apply_migration(migration)
else:
self.unapply_migration(migration)
def apply_migration(self, migration):
"""
Runs a migration forwards.
"""
print "Applying %s" % migration
with self.connection.schema_editor() as schema_editor:
project_state = self.loader.graph.project_state((migration.app_label, migration.name), at_end=False)
migration.apply(project_state, schema_editor)
self.recorder.record_applied(migration.app_label, migration.name)
print "Finished %s" % migration
def unapply_migration(self, migration):
"""
Runs a migration backwards.
"""
print "Unapplying %s" % migration
with self.connection.schema_editor() as schema_editor:
project_state = self.loader.graph.project_state((migration.app_label, migration.name), at_end=False)
migration.unapply(project_state, schema_editor)
self.recorder.record_unapplied(migration.app_label, migration.name)
print "Finished %s" % migration

48
django/db/migrations/migration.py
View File

@ -36,6 +36,17 @@ class Migration(object):
self.name = name
self.app_label = app_label
def __eq__(self, other):
if not isinstance(other, Migration):
return False
return (self.name == other.name) and (self.app_label == other.app_label)
def __ne__(self, other):
return not (self == other)
def __repr__(self):
return "<Migration %s.%s>" % (self.app_label, self.name)
def mutate_state(self, project_state):
"""
Takes a ProjectState and returns a new one with the migration's
@ -45,3 +56,40 @@ class Migration(object):
for operation in self.operations:
operation.state_forwards(self.app_label, new_state)
return new_state
def apply(self, project_state, schema_editor):
"""
Takes a project_state representing all migrations prior to this one
and a schema_editor for a live database and applies the migration
in a forwards order.
Returns the resulting project state for efficient re-use by following
Migrations.
"""
for operation in self.operations:
# Get the state after the operation has run
new_state = project_state.clone()
operation.state_forwards(self.app_label, new_state)
# Run the operation
operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
# Switch states
project_state = new_state
return project_state
def unapply(self, project_state, schema_editor):
"""
Takes a project_state representing all migrations prior to this one
and a schema_editor for a live database and applies the migration
in a reverse order.
"""
# We need to pre-calculate the stack of project states
to_run = []
for operation in self.operations:
new_state = project_state.clone()
operation.state_forwards(self.app_label, new_state)
to_run.append((operation, project_state, new_state))
project_state = new_state
# Now run them in reverse
to_run.reverse()
for operation, to_state, from_state in to_run:
operation.database_backwards(self.app_label, schema_editor, from_state, to_state)

16
django/db/migrations/operations/fields.py
View File

@ -16,13 +16,13 @@ class AddField(Operation):
def database_forwards(self, app_label, schema_editor, from_state, to_state):
app_cache = to_state.render()
model = app_cache.get_model(app_label, self.name)
schema_editor.add_field(model, model._meta.get_field_by_name(self.name))
model = app_cache.get_model(app_label, self.model_name)
schema_editor.add_field(model, model._meta.get_field_by_name(self.name)[0])
def database_backwards(self, app_label, schema_editor, from_state, to_state):
app_cache = from_state.render()
model = app_cache.get_model(app_label, self.name)
schema_editor.remove_field(model, model._meta.get_field_by_name(self.name))
model = app_cache.get_model(app_label, self.model_name)
schema_editor.remove_field(model, model._meta.get_field_by_name(self.name)[0])
class RemoveField(Operation):
@ -43,10 +43,10 @@ class RemoveField(Operation):
def database_forwards(self, app_label, schema_editor, from_state, to_state):
app_cache = from_state.render()
model = app_cache.get_model(app_label, self.name)
schema_editor.remove_field(model, model._meta.get_field_by_name(self.name))
model = app_cache.get_model(app_label, self.model_name)
schema_editor.remove_field(model, model._meta.get_field_by_name(self.name)[0])
def database_backwards(self, app_label, schema_editor, from_state, to_state):
app_cache = to_state.render()
model = app_cache.get_model(app_label, self.name)
schema_editor.add_field(model, model._meta.get_field_by_name(self.name))
model = app_cache.get_model(app_label, self.model_name)
schema_editor.add_field(model, model._meta.get_field_by_name(self.name)[0])

2
tests/migrations/migrations/0002_second.py
View File

@ -11,7 +11,7 @@ class Migration(migrations.Migration):
migrations.RemoveField("Author", "silly_field"),
migrations.AddField("Author", "important", models.BooleanField()),
migrations.AddField("Author", "rating", models.IntegerField(default=0)),
migrations.CreateModel(
"Book",

35
tests/migrations/test_executor.py Normal file
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@ -0,0 +1,35 @@
from django.test import TransactionTestCase
from django.db import connection
from django.db.migrations.executor import MigrationExecutor
class ExecutorTests(TransactionTestCase):
"""
Tests the migration executor (full end-to-end running).
Bear in mind that if these are failing you should fix the other
test failures first, as they may be propagating into here.
"""
def test_run(self):
"""
Tests running a simple set of migrations.
"""
executor = MigrationExecutor(connection)
# Let's look at the plan first and make sure it's up to scratch
plan = executor.migration_plan([("migrations", "0002_second")])
self.assertEqual(
plan,
[
(executor.loader.graph.nodes["migrations", "0001_initial"], False),
(executor.loader.graph.nodes["migrations", "0002_second"], False),
],
)
# Were the tables there before?
self.assertNotIn("migrations_author", connection.introspection.get_table_list(connection.cursor()))
self.assertNotIn("migrations_book", connection.introspection.get_table_list(connection.cursor()))
# Alright, let's try running it
executor.migrate([("migrations", "0002_second")])
# Are the tables there now?
self.assertIn("migrations_author", connection.introspection.get_table_list(connection.cursor()))
self.assertIn("migrations_book", connection.introspection.get_table_list(connection.cursor()))

2
tests/migrations/test_loader.py
View File

@ -54,7 +54,7 @@ class LoaderTests(TransactionTestCase):
author_state = project_state.models["migrations", "author"]
self.assertEqual(
[x for x, y in author_state.fields],
["id", "name", "slug", "age", "important"]
["id", "name", "slug", "age", "rating"]
)
book_state = project_state.models["migrations", "book"]

28
tests/migrations/test_operations.py
View File

@ -1,6 +1,6 @@
from django.test import TransactionTestCase
from django.db import connection, models, migrations
from django.db.migrations.state import ProjectState, ModelState
from django.db.migrations.state import ProjectState
class OperationTests(TransactionTestCase):
@ -16,6 +16,12 @@ class OperationTests(TransactionTestCase):
def assertTableNotExists(self, table):
self.assertNotIn(table, connection.introspection.get_table_list(connection.cursor()))
def assertColumnExists(self, table, column):
self.assertIn(column, [c.name for c in connection.introspection.get_table_description(connection.cursor(), table)])
def assertColumnNotExists(self, table, column):
self.assertNotIn(column, [c.name for c in connection.introspection.get_table_description(connection.cursor(), table)])
def set_up_test_model(self, app_label):
"""
Creates a test model state and database table.
@ -82,3 +88,23 @@ class OperationTests(TransactionTestCase):
with connection.schema_editor() as editor:
operation.database_backwards("test_dlmo", editor, new_state, project_state)
self.assertTableExists("test_dlmo_pony")
def test_add_field(self):
"""
Tests the AddField operation.
"""
project_state = self.set_up_test_model("test_adfl")
# Test the state alteration
operation = migrations.AddField("Pony", "height", models.FloatField(null=True))
new_state = project_state.clone()
operation.state_forwards("test_adfl", new_state)
self.assertEqual(len(new_state.models["test_adfl", "pony"].fields), 3)
# Test the database alteration
self.assertColumnNotExists("test_adfl_pony", "height")
with connection.schema_editor() as editor:
operation.database_forwards("test_adfl", editor, project_state, new_state)
self.assertColumnExists("test_adfl_pony", "height")
# And test reversal
with connection.schema_editor() as editor:
operation.database_backwards("test_adfl", editor, new_state, project_state)
self.assertColumnNotExists("test_adfl_pony", "height")