django1/django/db/migrations/autodetector.py

410 lines
20 KiB
Python
Raw Normal View History

import re
import datetime
from django.db.migrations import operations
from django.db.migrations.migration import Migration
from django.db.migrations.questioner import MigrationQuestioner
2013-06-07 22:49:48 +08:00
class MigrationAutodetector(object):
"""
Takes a pair of ProjectStates, and compares them to see what the
first would need doing to make it match the second (the second
usually being the project's current state).
Note that this naturally operates on entire projects at a time,
as it's likely that changes interact (for example, you can't
add a ForeignKey without having a migration to add the table it
depends on first). A user interface may offer single-app usage
if it wishes, with the caveat that it may not always be possible.
"""
def __init__(self, from_state, to_state, questioner=None):
self.from_state = from_state
self.to_state = to_state
self.questioner = questioner or MigrationQuestioner()
def changes(self, graph, trim_to_apps=None):
"""
Main entry point to produce a list of appliable changes.
Takes a graph to base names on and an optional set of apps
to try and restrict to (restriction is not guaranteed)
"""
changes = self._detect_changes()
changes = self.arrange_for_graph(changes, graph)
if trim_to_apps:
changes = self._trim_to_apps(changes, trim_to_apps)
return changes
def _detect_changes(self):
"""
Returns a dict of migration plans which will achieve the
change from from_state to to_state. The dict has app labels
2013-08-11 03:00:12 +08:00
as keys and a list of migrations as values.
The resulting migrations aren't specially named, but the names
do matter for dependencies inside the set.
"""
# We'll store migrations as lists by app names for now
self.migrations = {}
old_apps = self.from_state.render()
new_apps = self.to_state.render()
# Prepare lists of old/new model keys that we care about
# (i.e. ignoring proxy ones)
old_model_keys = [
(al, mn)
for al, mn in self.from_state.models.keys()
if not old_apps.get_model(al, mn)._meta.proxy
]
new_model_keys = [
(al, mn)
for al, mn in self.to_state.models.keys()
if not new_apps.get_model(al, mn)._meta.proxy
]
# Adding models. Phase 1 is adding models with no outward relationships.
added_models = set(new_model_keys) - set(old_model_keys)
pending_add = {}
for app_label, model_name in added_models:
model_state = self.to_state.models[app_label, model_name]
# Are there any relationships out from this model? if so, punt it to the next phase.
related_fields = []
for field in new_apps.get_model(app_label, model_name)._meta.local_fields:
if field.rel:
if field.rel.to:
related_fields.append((field.name, field.rel.to._meta.app_label, field.rel.to._meta.model_name))
if hasattr(field.rel, "through") and not field.rel.through._meta.auto_created:
related_fields.append((field.name, field.rel.through._meta.app_label, field.rel.through._meta.model_name))
for field in new_apps.get_model(app_label, model_name)._meta.local_many_to_many:
if field.rel.to:
related_fields.append((field.name, field.rel.to._meta.app_label, field.rel.to._meta.model_name))
if hasattr(field.rel, "through") and not field.rel.through._meta.auto_created:
related_fields.append((field.name, field.rel.through._meta.app_label, field.rel.through._meta.model_name))
if related_fields:
pending_add[app_label, model_name] = related_fields
else:
self.add_to_migration(
app_label,
operations.CreateModel(
2013-11-03 17:22:11 +08:00
name=model_state.name,
fields=model_state.fields,
options=model_state.options,
bases=model_state.bases,
)
)
# Phase 2 is progressively adding pending models, splitting up into two
# migrations if required.
pending_new_fks = []
while pending_add:
# Is there one we can add that has all dependencies satisfied?
satisfied = [(m, rf) for m, rf in pending_add.items() if all((al, mn) not in pending_add for f, al, mn in rf)]
if satisfied:
(app_label, model_name), related_fields = sorted(satisfied)[0]
model_state = self.to_state.models[app_label, model_name]
self.add_to_migration(
app_label,
operations.CreateModel(
2013-11-03 17:22:11 +08:00
name=model_state.name,
fields=model_state.fields,
options=model_state.options,
bases=model_state.bases,
)
)
for field_name, other_app_label, other_model_name in related_fields:
# If it depends on a swappable something, add a dynamic depend'cy
swappable_setting = new_apps.get_model(app_label, model_name)._meta.get_field_by_name(field_name)[0].swappable_setting
if swappable_setting is not None:
self.add_swappable_dependency(app_label, swappable_setting)
elif app_label != other_app_label:
self.add_dependency(app_label, other_app_label)
del pending_add[app_label, model_name]
# Ah well, we'll need to split one. Pick deterministically.
else:
(app_label, model_name), related_fields = sorted(pending_add.items())[0]
model_state = self.to_state.models[app_label, model_name]
# Work out the fields that need splitting out
bad_fields = dict((f, (al, mn)) for f, al, mn in related_fields if (al, mn) in pending_add)
# Create the model, without those
self.add_to_migration(
app_label,
operations.CreateModel(
2013-11-03 17:22:11 +08:00
name=model_state.name,
fields=[(n, f) for n, f in model_state.fields if n not in bad_fields],
options=model_state.options,
bases=model_state.bases,
)
)
# Add the bad fields to be made in a phase 3
for field_name, (other_app_label, other_model_name) in bad_fields.items():
pending_new_fks.append((app_label, model_name, field_name, other_app_label))
del pending_add[app_label, model_name]
# Phase 3 is adding the final set of FKs as separate new migrations
for app_label, model_name, field_name, other_app_label in pending_new_fks:
2013-06-07 22:49:48 +08:00
model_state = self.to_state.models[app_label, model_name]
self.add_to_migration(
app_label,
operations.AddField(
2013-11-03 17:22:11 +08:00
model_name=model_name,
name=field_name,
field=model_state.get_field_by_name(field_name),
),
2013-11-03 17:22:11 +08:00
new=True,
)
# If it depends on a swappable something, add a dynamic depend'cy
swappable_setting = new_apps.get_model(app_label, model_name)._meta.get_field_by_name(field_name)[0].swappable_setting
if swappable_setting is not None:
self.add_swappable_dependency(app_label, swappable_setting)
elif app_label != other_app_label:
self.add_dependency(app_label, other_app_label)
# Removing models
removed_models = set(old_model_keys) - set(new_model_keys)
for app_label, model_name in removed_models:
2013-06-07 22:49:48 +08:00
model_state = self.from_state.models[app_label, model_name]
self.add_to_migration(
app_label,
operations.DeleteModel(
model_state.name,
)
)
# Changes within models
kept_models = set(old_model_keys).intersection(new_model_keys)
old_fields = set()
new_fields = set()
unique_together_operations = []
for app_label, model_name in kept_models:
old_model_state = self.from_state.models[app_label, model_name]
new_model_state = self.to_state.models[app_label, model_name]
# Collect field changes for later global dealing with (so AddFields
# always come before AlterFields even on separate models)
old_fields.update((app_label, model_name, x) for x, y in old_model_state.fields)
new_fields.update((app_label, model_name, x) for x, y in new_model_state.fields)
# Unique_together changes. Operations will be added to migration a
# bit later, after fields creation. See ticket #22035.
if old_model_state.options.get("unique_together", set()) != new_model_state.options.get("unique_together", set()):
unique_together_operations.append((
app_label,
operations.AlterUniqueTogether(
name=model_name,
unique_together=new_model_state.options.get("unique_together", set()),
)
))
# New fields
for app_label, model_name, field_name in new_fields - old_fields:
old_model_state = self.from_state.models[app_label, model_name]
new_model_state = self.to_state.models[app_label, model_name]
field = new_model_state.get_field_by_name(field_name)
# Scan to see if this is actually a rename!
field_dec = field.deconstruct()[1:]
found_rename = False
for rem_app_label, rem_model_name, rem_field_name in (old_fields - new_fields):
if rem_app_label == app_label and rem_model_name == model_name:
if old_model_state.get_field_by_name(rem_field_name).deconstruct()[1:] == field_dec:
if self.questioner.ask_rename(model_name, rem_field_name, field_name, field):
self.add_to_migration(
app_label,
operations.RenameField(
2013-11-03 17:22:11 +08:00
model_name=model_name,
old_name=rem_field_name,
2013-11-03 17:22:11 +08:00
new_name=field_name,
)
)
old_fields.remove((rem_app_label, rem_model_name, rem_field_name))
new_fields.remove((app_label, model_name, field_name))
found_rename = True
break
if found_rename:
continue
# You can't just add NOT NULL fields with no default
if not field.null and not field.has_default():
field = field.clone()
field.default = self.questioner.ask_not_null_addition(field_name, model_name)
self.add_to_migration(
app_label,
operations.AddField(
2013-11-03 17:22:11 +08:00
model_name=model_name,
name=field_name,
field=field,
preserve_default=False,
)
)
else:
self.add_to_migration(
app_label,
operations.AddField(
model_name=model_name,
name=field_name,
field=field,
2013-06-20 22:19:30 +08:00
)
)
new_field = new_apps.get_model(app_label, model_name)._meta.get_field_by_name(field_name)[0]
swappable_setting = getattr(new_field, 'swappable_setting', None)
if swappable_setting is not None:
self.add_swappable_dependency(app_label, swappable_setting)
# Old fields
for app_label, model_name, field_name in old_fields - new_fields:
old_model_state = self.from_state.models[app_label, model_name]
new_model_state = self.to_state.models[app_label, model_name]
self.add_to_migration(
app_label,
operations.RemoveField(
model_name=model_name,
name=field_name,
)
)
# The same fields
for app_label, model_name, field_name in old_fields.intersection(new_fields):
# Did the field change?
old_model_state = self.from_state.models[app_label, model_name]
new_model_state = self.to_state.models[app_label, model_name]
old_field_dec = old_model_state.get_field_by_name(field_name).deconstruct()
new_field_dec = new_model_state.get_field_by_name(field_name).deconstruct()
if old_field_dec != new_field_dec:
self.add_to_migration(
app_label,
operations.AlterField(
model_name=model_name,
name=field_name,
field=new_model_state.get_field_by_name(field_name),
)
)
for app_label, operation in unique_together_operations:
self.add_to_migration(app_label, operation)
# Alright, now add internal dependencies
for app_label, migrations in self.migrations.items():
for m1, m2 in zip(migrations, migrations[1:]):
m2.dependencies.append((app_label, m1.name))
# Clean up dependencies
for app_label, migrations in self.migrations.items():
for migration in migrations:
migration.dependencies = list(set(migration.dependencies))
return self.migrations
def add_to_migration(self, app_label, operation, new=False):
migrations = self.migrations.setdefault(app_label, [])
if not migrations or new:
subclass = type("Migration", (Migration,), {"operations": [], "dependencies": []})
instance = subclass("auto_%i" % (len(migrations) + 1), app_label)
migrations.append(instance)
migrations[-1].operations.append(operation)
def add_dependency(self, app_label, other_app_label):
"""
Adds a dependency to app_label's newest migration on
other_app_label's latest migration.
"""
if self.migrations.get(other_app_label, []):
dependency = (other_app_label, self.migrations[other_app_label][-1].name)
else:
dependency = (other_app_label, "__first__")
self.migrations[app_label][-1].dependencies.append(dependency)
def add_swappable_dependency(self, app_label, setting_name):
"""
Adds a dependency to the value of a swappable model setting.
"""
dependency = ("__setting__", setting_name)
self.migrations[app_label][-1].dependencies.append(dependency)
def arrange_for_graph(self, changes, graph):
"""
Takes in a result from changes() and a MigrationGraph,
and fixes the names and dependencies of the changes so they
extend the graph from the leaf nodes for each app.
"""
leaves = graph.leaf_nodes()
name_map = {}
for app_label, migrations in list(changes.items()):
if not migrations:
continue
# Find the app label's current leaf node
app_leaf = None
for leaf in leaves:
if leaf[0] == app_label:
app_leaf = leaf
break
# Do they want an initial migration for this app?
if app_leaf is None and not self.questioner.ask_initial(app_label):
# They don't.
for migration in migrations:
name_map[(app_label, migration.name)] = (app_label, "__first__")
del changes[app_label]
continue
# Work out the next number in the sequence
if app_leaf is None:
next_number = 1
else:
next_number = (self.parse_number(app_leaf[1]) or 0) + 1
# Name each migration
for i, migration in enumerate(migrations):
if i == 0 and app_leaf:
migration.dependencies.append(app_leaf)
if i == 0 and not app_leaf:
new_name = "0001_initial"
else:
new_name = "%04i_%s" % (next_number, self.suggest_name(migration.operations))
name_map[(app_label, migration.name)] = (app_label, new_name)
migration.name = new_name
# Now fix dependencies
for app_label, migrations in changes.items():
for migration in migrations:
migration.dependencies = [name_map.get(d, d) for d in migration.dependencies]
return changes
def _trim_to_apps(self, changes, app_labels):
"""
Takes changes from arrange_for_graph and set of app labels and
returns a modified set of changes which trims out as many migrations
that are not in app_labels as possible.
Note that some other migrations may still be present, as they may be
required dependencies.
"""
# Gather other app dependencies in a first pass
app_dependencies = {}
for app_label, migrations in changes.items():
for migration in migrations:
for dep_app_label, name in migration.dependencies:
app_dependencies.setdefault(app_label, set()).add(dep_app_label)
required_apps = set(app_labels)
# Keep resolving till there's no change
old_required_apps = None
while old_required_apps != required_apps:
old_required_apps = set(required_apps)
for app_label in list(required_apps):
required_apps.update(app_dependencies.get(app_label, set()))
# Remove all migrations that aren't needed
for app_label in list(changes.keys()):
if app_label not in required_apps:
del changes[app_label]
return changes
@classmethod
def suggest_name(cls, ops):
"""
Given a set of operations, suggests a name for the migration
they might represent. Names are not guaranteed to be unique,
but we put some effort in to the fallback name to avoid VCS conflicts
if we can.
"""
if len(ops) == 1:
if isinstance(ops[0], operations.CreateModel):
return ops[0].name.lower()
elif isinstance(ops[0], operations.DeleteModel):
return "delete_%s" % ops[0].name.lower()
elif isinstance(ops[0], operations.AddField):
return "%s_%s" % (ops[0].model_name.lower(), ops[0].name.lower())
elif isinstance(ops[0], operations.RemoveField):
return "remove_%s_%s" % (ops[0].model_name.lower(), ops[0].name.lower())
elif len(ops) > 1:
if all(isinstance(o, operations.CreateModel) for o in ops):
return "_".join(sorted(o.name.lower() for o in ops))
return "auto_%s" % datetime.datetime.now().strftime("%Y%m%d_%H%M")
@classmethod
def parse_number(cls, name):
"""
Given a migration name, tries to extract a number from the
beginning of it. If no number found, returns None.
"""
if re.match(r"^\d+_", name):
return int(name.split("_")[0])
return None