Commit 21e21c7b authored by Patryk Zawadzki's avatar Patryk Zawadzki Committed by Tim Graham
Browse files

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

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
13d613f8.
parent 53908c1f

AUTHORS

+1 −0
Original line number Diff line number Diff line
@@ -378,6 +378,7 @@ answer newbie questions, and generally made Django that much better: 
    Kevin McConnell <kevin.mcconnell@gmail.com>

    Kieran Holland <http://www.kieranholland.com>

    kilian <kilian.cavalotti@lip6.fr>

    Klaas van Schelven <klaas@vanschelven.com>

    knox <christobzr@gmail.com>

    konrad@gwu.edu

    Kowito Charoenratchatabhan <kowito@felspar.com>

django/db/migrations/autodetector.py

+14 −22
Original line number Diff line number Diff line
@@ -14,6 +14,8 @@ from django.db.migrations.questioner import MigrationQuestioner 
from django.db.migrations.optimizer import MigrationOptimizer

from django.db.migrations.operations.models import AlterModelOptions



from .topological_sort import stable_topological_sort





class MigrationAutodetector(object):

    """
@@ -191,28 +193,18 @@ class MigrationAutodetector(object): 
        # isn't bad, but we need to pull a few things around so FKs work nicely

        # inside the same app

        for app_label, ops in sorted(self.generated_operations.items()):

            for i in range(10000):

                found = False

                for i, op in enumerate(ops):



            # construct a dependency graph for intra-app dependencies

            dependency_graph = {op: set() for op in ops}

            for op in ops:

                for dep in op._auto_deps:

                    if dep[0] == app_label:

                            # Alright, there's a dependency on the same app.

                            for j, op2 in enumerate(ops):

                                if j > i and self.check_dependency(op2, dep):

                                    # shift the operation from position i after

                                    # the operation at position j

                                    ops = ops[:i] + ops[i + 1:j + 1] + [op] + ops[j + 1:]

                                    found = True

                                    break

                        if found:

                            break

                    if found:

                        break

                if not found:

                    break

            else:

                raise ValueError("Infinite loop caught in operation dependency resolution")

            self.generated_operations[app_label] = ops

                        for op2 in ops:

                            if self.check_dependency(op2, dep):

                                dependency_graph[op].add(op2)



            # we use a stable sort for deterministic tests & general behavior

            self.generated_operations[app_label] = stable_topological_sort(ops, dependency_graph)



        # Now, we need to chop the lists of operations up into migrations with

        # dependencies on each other.

django/db/migrations/operations/base.py

+0 −6
Original line number Diff line number Diff line
@@ -116,9 +116,3 @@ class Operation(object): 
            ", ".join(map(repr, self._constructor_args[0])),

            ",".join(" %s=%r" % x for x in self._constructor_args[1].items()),

        )
 


    def __eq__(self, other):

        return (self.__class__ == other.__class__) and (self.deconstruct() == other.deconstruct())



    def __ne__(self, other):

        return not (self == other)

django/db/migrations/operations/fields.py

+34 −16
Original line number Diff line number Diff line
@@ -16,6 +16,16 @@ class AddField(Operation): 
        self.field = field

        self.preserve_default = preserve_default



    def deconstruct(self):

        kwargs = {}

        if self.preserve_default is not True:

            kwargs['preserve_default'] = self.preserve_default

        return (

            self.__class__.__name__,

            [self.model_name, self.name, self.field],

            kwargs

        )



    def state_forwards(self, app_label, state):

        # If preserve default is off, don't use the default for future state

        if not self.preserve_default:
@@ -47,14 +57,6 @@ class AddField(Operation): 
    def describe(self):

        return "Add field %s to %s" % (self.name, self.model_name)



    def __eq__(self, other):

        return (

            (self.__class__ == other.__class__) and

            (self.name == other.name) and

            (self.model_name.lower() == other.model_name.lower()) and

            (self.field.deconstruct()[1:] == other.field.deconstruct()[1:])

        )



    def references_model(self, name, app_label=None):

        return name.lower() == self.model_name.lower()
@@ -71,6 +73,13 @@ class RemoveField(Operation): 
        self.model_name = model_name

        self.name = name



    def deconstruct(self):

        return (

            self.__class__.__name__,

            [self.model_name, self.name],

            {}

        )



    def state_forwards(self, app_label, state):

        new_fields = []

        for name, instance in state.models[app_label, self.model_name.lower()].fields:
@@ -110,6 +119,16 @@ class AlterField(Operation): 
        self.field = field

        self.preserve_default = preserve_default



    def deconstruct(self):

        kwargs = {}

        if self.preserve_default is not True:

            kwargs['preserve_default'] = self.preserve_default

        return (

            self.__class__.__name__,

            [self.model_name, self.name, self.field],

            kwargs

        )



    def state_forwards(self, app_label, state):

        if not self.preserve_default:

            field = self.field.clone()
@@ -146,14 +165,6 @@ class AlterField(Operation): 
    def describe(self):

        return "Alter field %s on %s" % (self.name, self.model_name)



    def __eq__(self, other):

        return (

            (self.__class__ == other.__class__) and

            (self.name == other.name) and

            (self.model_name.lower() == other.model_name.lower()) and

            (self.field.deconstruct()[1:] == other.field.deconstruct()[1:])

        )



    def references_model(self, name, app_label=None):

        return name.lower() == self.model_name.lower()
@@ -171,6 +182,13 @@ class RenameField(Operation): 
        self.old_name = old_name

        self.new_name = new_name



    def deconstruct(self):

        return (

            self.__class__.__name__,

            [self.model_name, self.old_name, self.new_name],

            {}

        )



    def state_forwards(self, app_label, state):

        # Rename the field

        state.models[app_label, self.model_name.lower()].fields = [

django/db/migrations/operations/models.py

+61 −9
Original line number Diff line number Diff line
@@ -20,6 +20,18 @@ class CreateModel(Operation): 
        self.options = options or {}

        self.bases = bases or (models.Model,)



    def deconstruct(self):

        kwargs = {}

        if self.options:

            kwargs['options'] = self.options

        if self.bases and self.bases != (models.Model,):

            kwargs['bases'] = self.bases

        return (

            self.__class__.__name__,

            [self.name, self.fields],

            kwargs

        )



    def state_forwards(self, app_label, state):

        state.models[app_label, self.name.lower()] = ModelState(

            app_label,
@@ -61,15 +73,6 @@ class CreateModel(Operation): 
                return True

        return False



    def __eq__(self, other):

        return (

            (self.__class__ == other.__class__) and

            (self.name == other.name) and

            (self.options == other.options) and

            (self.bases == other.bases) and

            ([(k, f.deconstruct()[1:]) for k, f in self.fields] == [(k, f.deconstruct()[1:]) for k, f in other.fields])

        )





class DeleteModel(Operation):

    """
@@ -79,6 +82,13 @@ class DeleteModel(Operation): 
    def __init__(self, name):

        self.name = name



    def deconstruct(self):

        return (

            self.__class__.__name__,

            [self.name],

            {}

        )



    def state_forwards(self, app_label, state):

        del state.models[app_label, self.name.lower()]
@@ -110,6 +120,13 @@ class RenameModel(Operation): 
        self.old_name = old_name

        self.new_name = new_name



    def deconstruct(self):

        return (

            self.__class__.__name__,

            [self.old_name, self.new_name],

            {}

        )



    def state_forwards(self, app_label, state):

        # Get all of the related objects we need to repoint

        apps = state.render(skip_cache=True)
@@ -196,6 +213,13 @@ class AlterModelTable(Operation): 
        self.name = name

        self.table = table



    def deconstruct(self):

        return (

            self.__class__.__name__,

            [self.name, self.table],

            {}

        )



    def state_forwards(self, app_label, state):

        state.models[app_label, self.name.lower()].options["db_table"] = self.table
@@ -241,6 +265,13 @@ class AlterUniqueTogether(Operation): 
        unique_together = normalize_together(unique_together)

        self.unique_together = set(tuple(cons) for cons in unique_together)



    def deconstruct(self):

        return (

            self.__class__.__name__,

            [self.name, self.unique_together],

            {}

        )



    def state_forwards(self, app_label, state):

        model_state = state.models[app_label, self.name.lower()]

        model_state.options[self.option_name] = self.unique_together
@@ -279,6 +310,13 @@ class AlterIndexTogether(Operation): 
        index_together = normalize_together(index_together)

        self.index_together = set(tuple(cons) for cons in index_together)



    def deconstruct(self):

        return (

            self.__class__.__name__,

            [self.name, self.index_together],

            {}

        )



    def state_forwards(self, app_label, state):

        model_state = state.models[app_label, self.name.lower()]

        model_state.options[self.option_name] = self.index_together
@@ -314,6 +352,13 @@ class AlterOrderWithRespectTo(Operation): 
        self.name = name

        self.order_with_respect_to = order_with_respect_to



    def deconstruct(self):

        return (

            self.__class__.__name__,

            [self.name, self.order_with_respect_to],

            {}

        )



    def state_forwards(self, app_label, state):

        model_state = state.models[app_label, self.name.lower()]

        model_state.options['order_with_respect_to'] = self.order_with_respect_to
@@ -366,6 +411,13 @@ class AlterModelOptions(Operation): 
        self.name = name

        self.options = options



    def deconstruct(self):

        return (

            self.__class__.__name__,

            [self.name, self.options],

            {}

        )



    def state_forwards(self, app_label, state):

        model_state = state.models[app_label, self.name.lower()]

        model_state.options = dict(model_state.options)