Initial commit. Basic models mostly done.

This commit is contained in:
tcaxle
2020-04-11 13:03:48 +01:00
commit 840e3c86f9
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from .fields import AddField, AlterField, RemoveField, RenameField
from .models import (
AddConstraint, AddIndex, AlterIndexTogether, AlterModelManagers,
AlterModelOptions, AlterModelTable, AlterOrderWithRespectTo,
AlterUniqueTogether, CreateModel, DeleteModel, RemoveConstraint,
RemoveIndex, RenameModel,
)
from .special import RunPython, RunSQL, SeparateDatabaseAndState
__all__ = [
'CreateModel', 'DeleteModel', 'AlterModelTable', 'AlterUniqueTogether',
'RenameModel', 'AlterIndexTogether', 'AlterModelOptions', 'AddIndex',
'RemoveIndex', 'AddField', 'RemoveField', 'AlterField', 'RenameField',
'AddConstraint', 'RemoveConstraint',
'SeparateDatabaseAndState', 'RunSQL', 'RunPython',
'AlterOrderWithRespectTo', 'AlterModelManagers',
]

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from django.db import router
from django.db.models.fields.related import RECURSIVE_RELATIONSHIP_CONSTANT
class Operation:
"""
Base class for migration operations.
It's responsible for both mutating the in-memory model state
(see db/migrations/state.py) to represent what it performs, as well
as actually performing it against a live database.
Note that some operations won't modify memory state at all (e.g. data
copying operations), and some will need their modifications to be
optionally specified by the user (e.g. custom Python code snippets)
Due to the way this class deals with deconstruction, it should be
considered immutable.
"""
# If this migration can be run in reverse.
# Some operations are impossible to reverse, like deleting data.
reversible = True
# Can this migration be represented as SQL? (things like RunPython cannot)
reduces_to_sql = True
# Should this operation be forced as atomic even on backends with no
# DDL transaction support (i.e., does it have no DDL, like RunPython)
atomic = False
# Should this operation be considered safe to elide and optimize across?
elidable = False
serialization_expand_args = []
def __new__(cls, *args, **kwargs):
# We capture the arguments to make returning them trivial
self = object.__new__(cls)
self._constructor_args = (args, kwargs)
return self
def deconstruct(self):
"""
Return a 3-tuple of class import path (or just name if it lives
under django.db.migrations), positional arguments, and keyword
arguments.
"""
return (
self.__class__.__name__,
self._constructor_args[0],
self._constructor_args[1],
)
def state_forwards(self, app_label, state):
"""
Take the state from the previous migration, and mutate it
so that it matches what this migration would perform.
"""
raise NotImplementedError('subclasses of Operation must provide a state_forwards() method')
def database_forwards(self, app_label, schema_editor, from_state, to_state):
"""
Perform the mutation on the database schema in the normal
(forwards) direction.
"""
raise NotImplementedError('subclasses of Operation must provide a database_forwards() method')
def database_backwards(self, app_label, schema_editor, from_state, to_state):
"""
Perform the mutation on the database schema in the reverse
direction - e.g. if this were CreateModel, it would in fact
drop the model's table.
"""
raise NotImplementedError('subclasses of Operation must provide a database_backwards() method')
def describe(self):
"""
Output a brief summary of what the action does.
"""
return "%s: %s" % (self.__class__.__name__, self._constructor_args)
def references_model(self, name, app_label=None):
"""
Return True if there is a chance this operation references the given
model name (as a string), with an optional app label for accuracy.
Used for optimization. If in doubt, return True;
returning a false positive will merely make the optimizer a little
less efficient, while returning a false negative may result in an
unusable optimized migration.
"""
return True
def references_field(self, model_name, name, app_label=None):
"""
Return True if there is a chance this operation references the given
field name, with an optional app label for accuracy.
Used for optimization. If in doubt, return True.
"""
return self.references_model(model_name, app_label)
def allow_migrate_model(self, connection_alias, model):
"""
Return whether or not a model may be migrated.
This is a thin wrapper around router.allow_migrate_model() that
preemptively rejects any proxy, swapped out, or unmanaged model.
"""
if not model._meta.can_migrate(connection_alias):
return False
return router.allow_migrate_model(connection_alias, model)
def reduce(self, operation, app_label=None):
"""
Return either a list of operations the actual operation should be
replaced with or a boolean that indicates whether or not the specified
operation can be optimized across.
"""
if self.elidable:
return [operation]
elif operation.elidable:
return [self]
return False
def _get_model_tuple(self, remote_model, app_label, model_name):
if remote_model == RECURSIVE_RELATIONSHIP_CONSTANT:
return app_label, model_name.lower()
elif '.' in remote_model:
return tuple(remote_model.lower().split('.'))
else:
return app_label, remote_model.lower()
def __repr__(self):
return "<%s %s%s>" % (
self.__class__.__name__,
", ".join(map(repr, self._constructor_args[0])),
",".join(" %s=%r" % x for x in self._constructor_args[1].items()),
)

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from django.core.exceptions import FieldDoesNotExist
from django.db.models.fields import NOT_PROVIDED
from django.utils.functional import cached_property
from .base import Operation
from .utils import (
ModelTuple, field_references_model, is_referenced_by_foreign_key,
)
class FieldOperation(Operation):
def __init__(self, model_name, name, field=None):
self.model_name = model_name
self.name = name
self.field = field
@cached_property
def model_name_lower(self):
return self.model_name.lower()
@cached_property
def name_lower(self):
return self.name.lower()
def is_same_model_operation(self, operation):
return self.model_name_lower == operation.model_name_lower
def is_same_field_operation(self, operation):
return self.is_same_model_operation(operation) and self.name_lower == operation.name_lower
def references_model(self, name, app_label=None):
name_lower = name.lower()
if name_lower == self.model_name_lower:
return True
if self.field:
return field_references_model(self.field, ModelTuple(app_label, name_lower))
return False
def references_field(self, model_name, name, app_label=None):
model_name_lower = model_name.lower()
# Check if this operation locally references the field.
if model_name_lower == self.model_name_lower:
if name == self.name:
return True
elif self.field and hasattr(self.field, 'from_fields') and name in self.field.from_fields:
return True
# Check if this operation remotely references the field.
if self.field:
model_tuple = ModelTuple(app_label, model_name_lower)
remote_field = self.field.remote_field
if remote_field:
if (ModelTuple.from_model(remote_field.model) == model_tuple and
(not hasattr(self.field, 'to_fields') or
name in self.field.to_fields or None in self.field.to_fields)):
return True
through = getattr(remote_field, 'through', None)
if (through and ModelTuple.from_model(through) == model_tuple and
(getattr(remote_field, 'through_fields', None) is None or
name in remote_field.through_fields)):
return True
return False
def reduce(self, operation, app_label=None):
return (
super().reduce(operation, app_label=app_label) or
not operation.references_field(self.model_name, self.name, app_label)
)
class AddField(FieldOperation):
"""Add a field to a model."""
def __init__(self, model_name, name, field, preserve_default=True):
self.preserve_default = preserve_default
super().__init__(model_name, name, field)
def deconstruct(self):
kwargs = {
'model_name': self.model_name,
'name': self.name,
'field': self.field,
}
if self.preserve_default is not True:
kwargs['preserve_default'] = self.preserve_default
return (
self.__class__.__name__,
[],
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:
field = self.field.clone()
field.default = NOT_PROVIDED
else:
field = self.field
state.models[app_label, self.model_name_lower].fields.append((self.name, field))
# Delay rendering of relationships if it's not a relational field
delay = not field.is_relation
state.reload_model(app_label, self.model_name_lower, delay=delay)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
to_model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, to_model):
from_model = from_state.apps.get_model(app_label, self.model_name)
field = to_model._meta.get_field(self.name)
if not self.preserve_default:
field.default = self.field.default
schema_editor.add_field(
from_model,
field,
)
if not self.preserve_default:
field.default = NOT_PROVIDED
def database_backwards(self, app_label, schema_editor, from_state, to_state):
from_model = from_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, from_model):
schema_editor.remove_field(from_model, from_model._meta.get_field(self.name))
def describe(self):
return "Add field %s to %s" % (self.name, self.model_name)
def reduce(self, operation, app_label=None):
if isinstance(operation, FieldOperation) and self.is_same_field_operation(operation):
if isinstance(operation, AlterField):
return [
AddField(
model_name=self.model_name,
name=operation.name,
field=operation.field,
),
]
elif isinstance(operation, RemoveField):
return []
elif isinstance(operation, RenameField):
return [
AddField(
model_name=self.model_name,
name=operation.new_name,
field=self.field,
),
]
return super().reduce(operation, app_label=app_label)
class RemoveField(FieldOperation):
"""Remove a field from a model."""
def deconstruct(self):
kwargs = {
'model_name': self.model_name,
'name': self.name,
}
return (
self.__class__.__name__,
[],
kwargs
)
def state_forwards(self, app_label, state):
new_fields = []
old_field = None
for name, instance in state.models[app_label, self.model_name_lower].fields:
if name != self.name:
new_fields.append((name, instance))
else:
old_field = instance
state.models[app_label, self.model_name_lower].fields = new_fields
# Delay rendering of relationships if it's not a relational field
delay = not old_field.is_relation
state.reload_model(app_label, self.model_name_lower, delay=delay)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
from_model = from_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, from_model):
schema_editor.remove_field(from_model, from_model._meta.get_field(self.name))
def database_backwards(self, app_label, schema_editor, from_state, to_state):
to_model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, to_model):
from_model = from_state.apps.get_model(app_label, self.model_name)
schema_editor.add_field(from_model, to_model._meta.get_field(self.name))
def describe(self):
return "Remove field %s from %s" % (self.name, self.model_name)
def reduce(self, operation, app_label=None):
from .models import DeleteModel
if isinstance(operation, DeleteModel) and operation.name_lower == self.model_name_lower:
return [operation]
return super().reduce(operation, app_label=app_label)
class AlterField(FieldOperation):
"""
Alter a field's database column (e.g. null, max_length) to the provided
new field.
"""
def __init__(self, model_name, name, field, preserve_default=True):
self.preserve_default = preserve_default
super().__init__(model_name, name, field)
def deconstruct(self):
kwargs = {
'model_name': self.model_name,
'name': self.name,
'field': self.field,
}
if self.preserve_default is not True:
kwargs['preserve_default'] = self.preserve_default
return (
self.__class__.__name__,
[],
kwargs
)
def state_forwards(self, app_label, state):
if not self.preserve_default:
field = self.field.clone()
field.default = NOT_PROVIDED
else:
field = self.field
state.models[app_label, self.model_name_lower].fields = [
(n, field if n == self.name else f)
for n, f in
state.models[app_label, self.model_name_lower].fields
]
# TODO: investigate if old relational fields must be reloaded or if it's
# sufficient if the new field is (#27737).
# Delay rendering of relationships if it's not a relational field and
# not referenced by a foreign key.
delay = (
not field.is_relation and
not is_referenced_by_foreign_key(state, self.model_name_lower, self.field, self.name)
)
state.reload_model(app_label, self.model_name_lower, delay=delay)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
to_model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, to_model):
from_model = from_state.apps.get_model(app_label, self.model_name)
from_field = from_model._meta.get_field(self.name)
to_field = to_model._meta.get_field(self.name)
if not self.preserve_default:
to_field.default = self.field.default
schema_editor.alter_field(from_model, from_field, to_field)
if not self.preserve_default:
to_field.default = NOT_PROVIDED
def database_backwards(self, app_label, schema_editor, from_state, to_state):
self.database_forwards(app_label, schema_editor, from_state, to_state)
def describe(self):
return "Alter field %s on %s" % (self.name, self.model_name)
def reduce(self, operation, app_label=None):
if isinstance(operation, RemoveField) and self.is_same_field_operation(operation):
return [operation]
elif isinstance(operation, RenameField) and self.is_same_field_operation(operation):
return [
operation,
AlterField(
model_name=self.model_name,
name=operation.new_name,
field=self.field,
),
]
return super().reduce(operation, app_label=app_label)
class RenameField(FieldOperation):
"""Rename a field on the model. Might affect db_column too."""
def __init__(self, model_name, old_name, new_name):
self.old_name = old_name
self.new_name = new_name
super().__init__(model_name, old_name)
@cached_property
def old_name_lower(self):
return self.old_name.lower()
@cached_property
def new_name_lower(self):
return self.new_name.lower()
def deconstruct(self):
kwargs = {
'model_name': self.model_name,
'old_name': self.old_name,
'new_name': self.new_name,
}
return (
self.__class__.__name__,
[],
kwargs
)
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.model_name_lower]
# Rename the field
fields = model_state.fields
found = False
delay = True
for index, (name, field) in enumerate(fields):
if not found and name == self.old_name:
fields[index] = (self.new_name, field)
found = True
# Fix from_fields to refer to the new field.
from_fields = getattr(field, 'from_fields', None)
if from_fields:
field.from_fields = tuple([
self.new_name if from_field_name == self.old_name else from_field_name
for from_field_name in from_fields
])
# Delay rendering of relationships if it's not a relational
# field and not referenced by a foreign key.
delay = delay and (
not field.is_relation and
not is_referenced_by_foreign_key(state, self.model_name_lower, field, self.name)
)
if not found:
raise FieldDoesNotExist(
"%s.%s has no field named '%s'" % (app_label, self.model_name, self.old_name)
)
# Fix index/unique_together to refer to the new field
options = model_state.options
for option in ('index_together', 'unique_together'):
if option in options:
options[option] = [
[self.new_name if n == self.old_name else n for n in together]
for together in options[option]
]
# Fix to_fields to refer to the new field.
model_tuple = app_label, self.model_name_lower
for (model_app_label, model_name), model_state in state.models.items():
for index, (name, field) in enumerate(model_state.fields):
remote_field = field.remote_field
if remote_field:
remote_model_tuple = self._get_model_tuple(
remote_field.model, model_app_label, model_name
)
if remote_model_tuple == model_tuple:
if getattr(remote_field, 'field_name', None) == self.old_name:
remote_field.field_name = self.new_name
to_fields = getattr(field, 'to_fields', None)
if to_fields:
field.to_fields = tuple([
self.new_name if to_field_name == self.old_name else to_field_name
for to_field_name in to_fields
])
state.reload_model(app_label, self.model_name_lower, delay=delay)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
to_model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, to_model):
from_model = from_state.apps.get_model(app_label, self.model_name)
schema_editor.alter_field(
from_model,
from_model._meta.get_field(self.old_name),
to_model._meta.get_field(self.new_name),
)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
to_model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, to_model):
from_model = from_state.apps.get_model(app_label, self.model_name)
schema_editor.alter_field(
from_model,
from_model._meta.get_field(self.new_name),
to_model._meta.get_field(self.old_name),
)
def describe(self):
return "Rename field %s on %s to %s" % (self.old_name, self.model_name, self.new_name)
def references_field(self, model_name, name, app_label=None):
return self.references_model(model_name) and (
name.lower() == self.old_name_lower or
name.lower() == self.new_name_lower
)
def reduce(self, operation, app_label=None):
if (isinstance(operation, RenameField) and
self.is_same_model_operation(operation) and
self.new_name_lower == operation.old_name_lower):
return [
RenameField(
self.model_name,
self.old_name,
operation.new_name,
),
]
# Skip `FieldOperation.reduce` as we want to run `references_field`
# against self.new_name.
return (
super(FieldOperation, self).reduce(operation, app_label=app_label) or
not operation.references_field(self.model_name, self.new_name, app_label)
)

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from django.db import models
from django.db.migrations.operations.base import Operation
from django.db.migrations.state import ModelState
from django.db.models.options import normalize_together
from django.utils.functional import cached_property
from .fields import (
AddField, AlterField, FieldOperation, RemoveField, RenameField,
)
from .utils import ModelTuple, field_references_model
def _check_for_duplicates(arg_name, objs):
used_vals = set()
for val in objs:
if val in used_vals:
raise ValueError(
"Found duplicate value %s in CreateModel %s argument." % (val, arg_name)
)
used_vals.add(val)
class ModelOperation(Operation):
def __init__(self, name):
self.name = name
@cached_property
def name_lower(self):
return self.name.lower()
def references_model(self, name, app_label=None):
return name.lower() == self.name_lower
def reduce(self, operation, app_label=None):
return (
super().reduce(operation, app_label=app_label) or
not operation.references_model(self.name, app_label)
)
class CreateModel(ModelOperation):
"""Create a model's table."""
serialization_expand_args = ['fields', 'options', 'managers']
def __init__(self, name, fields, options=None, bases=None, managers=None):
self.fields = fields
self.options = options or {}
self.bases = bases or (models.Model,)
self.managers = managers or []
super().__init__(name)
# Sanity-check that there are no duplicated field names, bases, or
# manager names
_check_for_duplicates('fields', (name for name, _ in self.fields))
_check_for_duplicates('bases', (
base._meta.label_lower if hasattr(base, '_meta') else
base.lower() if isinstance(base, str) else base
for base in self.bases
))
_check_for_duplicates('managers', (name for name, _ in self.managers))
def deconstruct(self):
kwargs = {
'name': self.name,
'fields': self.fields,
}
if self.options:
kwargs['options'] = self.options
if self.bases and self.bases != (models.Model,):
kwargs['bases'] = self.bases
if self.managers and self.managers != [('objects', models.Manager())]:
kwargs['managers'] = self.managers
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
state.add_model(ModelState(
app_label,
self.name,
list(self.fields),
dict(self.options),
tuple(self.bases),
list(self.managers),
))
def database_forwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.create_model(model)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
model = from_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.delete_model(model)
def describe(self):
return "Create %smodel %s" % ("proxy " if self.options.get("proxy", False) else "", self.name)
def references_model(self, name, app_label=None):
name_lower = name.lower()
if name_lower == self.name_lower:
return True
# Check we didn't inherit from the model
model_tuple = ModelTuple(app_label, name_lower)
for base in self.bases:
if (base is not models.Model and isinstance(base, (models.base.ModelBase, str)) and
ModelTuple.from_model(base) == model_tuple):
return True
# Check we have no FKs/M2Ms with it
for _name, field in self.fields:
if field_references_model(field, model_tuple):
return True
return False
def reduce(self, operation, app_label=None):
if (isinstance(operation, DeleteModel) and
self.name_lower == operation.name_lower and
not self.options.get("proxy", False)):
return []
elif isinstance(operation, RenameModel) and self.name_lower == operation.old_name_lower:
return [
CreateModel(
operation.new_name,
fields=self.fields,
options=self.options,
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, AlterModelOptions) and self.name_lower == operation.name_lower:
return [
CreateModel(
self.name,
fields=self.fields,
options={**self.options, **operation.options},
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, AlterTogetherOptionOperation) and self.name_lower == operation.name_lower:
return [
CreateModel(
self.name,
fields=self.fields,
options={**self.options, **{operation.option_name: operation.option_value}},
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, AlterOrderWithRespectTo) and self.name_lower == operation.name_lower:
return [
CreateModel(
self.name,
fields=self.fields,
options={**self.options, 'order_with_respect_to': operation.order_with_respect_to},
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, FieldOperation) and self.name_lower == operation.model_name_lower:
if isinstance(operation, AddField):
return [
CreateModel(
self.name,
fields=self.fields + [(operation.name, operation.field)],
options=self.options,
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, AlterField):
return [
CreateModel(
self.name,
fields=[
(n, operation.field if n == operation.name else v)
for n, v in self.fields
],
options=self.options,
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, RemoveField):
options = self.options.copy()
for option_name in ('unique_together', 'index_together'):
option = options.pop(option_name, None)
if option:
option = set(filter(bool, (
tuple(f for f in fields if f != operation.name_lower) for fields in option
)))
if option:
options[option_name] = option
order_with_respect_to = options.get('order_with_respect_to')
if order_with_respect_to == operation.name_lower:
del options['order_with_respect_to']
return [
CreateModel(
self.name,
fields=[
(n, v)
for n, v in self.fields
if n.lower() != operation.name_lower
],
options=options,
bases=self.bases,
managers=self.managers,
),
]
elif isinstance(operation, RenameField):
options = self.options.copy()
for option_name in ('unique_together', 'index_together'):
option = options.get(option_name)
if option:
options[option_name] = {
tuple(operation.new_name if f == operation.old_name else f for f in fields)
for fields in option
}
order_with_respect_to = options.get('order_with_respect_to')
if order_with_respect_to == operation.old_name:
options['order_with_respect_to'] = operation.new_name
return [
CreateModel(
self.name,
fields=[
(operation.new_name if n == operation.old_name else n, v)
for n, v in self.fields
],
options=options,
bases=self.bases,
managers=self.managers,
),
]
return super().reduce(operation, app_label=app_label)
class DeleteModel(ModelOperation):
"""Drop a model's table."""
def deconstruct(self):
kwargs = {
'name': self.name,
}
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
state.remove_model(app_label, self.name_lower)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
model = from_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.delete_model(model)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.create_model(model)
def references_model(self, name, app_label=None):
# The deleted model could be referencing the specified model through
# related fields.
return True
def describe(self):
return "Delete model %s" % self.name
class RenameModel(ModelOperation):
"""Rename a model."""
def __init__(self, old_name, new_name):
self.old_name = old_name
self.new_name = new_name
super().__init__(old_name)
@cached_property
def old_name_lower(self):
return self.old_name.lower()
@cached_property
def new_name_lower(self):
return self.new_name.lower()
def deconstruct(self):
kwargs = {
'old_name': self.old_name,
'new_name': self.new_name,
}
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
# Add a new model.
renamed_model = state.models[app_label, self.old_name_lower].clone()
renamed_model.name = self.new_name
state.models[app_label, self.new_name_lower] = renamed_model
# Repoint all fields pointing to the old model to the new one.
old_model_tuple = ModelTuple(app_label, self.old_name_lower)
new_remote_model = '%s.%s' % (app_label, self.new_name)
to_reload = []
for (model_app_label, model_name), model_state in state.models.items():
model_changed = False
for index, (name, field) in enumerate(model_state.fields):
changed_field = None
remote_field = field.remote_field
if remote_field:
remote_model_tuple = ModelTuple.from_model(
remote_field.model, model_app_label, model_name
)
if remote_model_tuple == old_model_tuple:
changed_field = field.clone()
changed_field.remote_field.model = new_remote_model
through_model = getattr(remote_field, 'through', None)
if through_model:
through_model_tuple = ModelTuple.from_model(
through_model, model_app_label, model_name
)
if through_model_tuple == old_model_tuple:
if changed_field is None:
changed_field = field.clone()
changed_field.remote_field.through = new_remote_model
if changed_field:
model_state.fields[index] = name, changed_field
model_changed = True
if model_changed:
to_reload.append((model_app_label, model_name))
# Reload models related to old model before removing the old model.
state.reload_models(to_reload, delay=True)
# Remove the old model.
state.remove_model(app_label, self.old_name_lower)
state.reload_model(app_label, self.new_name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
new_model = to_state.apps.get_model(app_label, self.new_name)
if self.allow_migrate_model(schema_editor.connection.alias, new_model):
old_model = from_state.apps.get_model(app_label, self.old_name)
# Move the main table
schema_editor.alter_db_table(
new_model,
old_model._meta.db_table,
new_model._meta.db_table,
)
# Alter the fields pointing to us
for related_object in old_model._meta.related_objects:
if related_object.related_model == old_model:
model = new_model
related_key = (app_label, self.new_name_lower)
else:
model = related_object.related_model
related_key = (
related_object.related_model._meta.app_label,
related_object.related_model._meta.model_name,
)
to_field = to_state.apps.get_model(
*related_key
)._meta.get_field(related_object.field.name)
schema_editor.alter_field(
model,
related_object.field,
to_field,
)
# Rename M2M fields whose name is based on this model's name.
fields = zip(old_model._meta.local_many_to_many, new_model._meta.local_many_to_many)
for (old_field, new_field) in fields:
# Skip self-referential fields as these are renamed above.
if new_field.model == new_field.related_model or not new_field.remote_field.through._meta.auto_created:
continue
# Rename the M2M table that's based on this model's name.
old_m2m_model = old_field.remote_field.through
new_m2m_model = new_field.remote_field.through
schema_editor.alter_db_table(
new_m2m_model,
old_m2m_model._meta.db_table,
new_m2m_model._meta.db_table,
)
# Rename the column in the M2M table that's based on this
# model's name.
schema_editor.alter_field(
new_m2m_model,
old_m2m_model._meta.get_field(old_model._meta.model_name),
new_m2m_model._meta.get_field(new_model._meta.model_name),
)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
self.new_name_lower, self.old_name_lower = self.old_name_lower, self.new_name_lower
self.new_name, self.old_name = self.old_name, self.new_name
self.database_forwards(app_label, schema_editor, from_state, to_state)
self.new_name_lower, self.old_name_lower = self.old_name_lower, self.new_name_lower
self.new_name, self.old_name = self.old_name, self.new_name
def references_model(self, name, app_label=None):
return (
name.lower() == self.old_name_lower or
name.lower() == self.new_name_lower
)
def describe(self):
return "Rename model %s to %s" % (self.old_name, self.new_name)
def reduce(self, operation, app_label=None):
if (isinstance(operation, RenameModel) and
self.new_name_lower == operation.old_name_lower):
return [
RenameModel(
self.old_name,
operation.new_name,
),
]
# Skip `ModelOperation.reduce` as we want to run `references_model`
# against self.new_name.
return (
super(ModelOperation, self).reduce(operation, app_label=app_label) or
not operation.references_model(self.new_name, app_label)
)
class ModelOptionOperation(ModelOperation):
def reduce(self, operation, app_label=None):
if isinstance(operation, (self.__class__, DeleteModel)) and self.name_lower == operation.name_lower:
return [operation]
return super().reduce(operation, app_label=app_label)
class AlterModelTable(ModelOptionOperation):
"""Rename a model's table."""
def __init__(self, name, table):
self.table = table
super().__init__(name)
def deconstruct(self):
kwargs = {
'name': self.name,
'table': self.table,
}
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
state.models[app_label, self.name_lower].options["db_table"] = self.table
state.reload_model(app_label, self.name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
new_model = to_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, new_model):
old_model = from_state.apps.get_model(app_label, self.name)
schema_editor.alter_db_table(
new_model,
old_model._meta.db_table,
new_model._meta.db_table,
)
# Rename M2M fields whose name is based on this model's db_table
for (old_field, new_field) in zip(old_model._meta.local_many_to_many, new_model._meta.local_many_to_many):
if new_field.remote_field.through._meta.auto_created:
schema_editor.alter_db_table(
new_field.remote_field.through,
old_field.remote_field.through._meta.db_table,
new_field.remote_field.through._meta.db_table,
)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
return self.database_forwards(app_label, schema_editor, from_state, to_state)
def describe(self):
return "Rename table for %s to %s" % (
self.name,
self.table if self.table is not None else "(default)"
)
class AlterTogetherOptionOperation(ModelOptionOperation):
option_name = None
def __init__(self, name, option_value):
if option_value:
option_value = set(normalize_together(option_value))
setattr(self, self.option_name, option_value)
super().__init__(name)
@cached_property
def option_value(self):
return getattr(self, self.option_name)
def deconstruct(self):
kwargs = {
'name': self.name,
self.option_name: self.option_value,
}
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.name_lower]
model_state.options[self.option_name] = self.option_value
state.reload_model(app_label, self.name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
new_model = to_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, new_model):
old_model = from_state.apps.get_model(app_label, self.name)
alter_together = getattr(schema_editor, 'alter_%s' % self.option_name)
alter_together(
new_model,
getattr(old_model._meta, self.option_name, set()),
getattr(new_model._meta, self.option_name, set()),
)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
return self.database_forwards(app_label, schema_editor, from_state, to_state)
def references_field(self, model_name, name, app_label=None):
return (
self.references_model(model_name, app_label) and
(
not self.option_value or
any((name in fields) for fields in self.option_value)
)
)
def describe(self):
return "Alter %s for %s (%s constraint(s))" % (self.option_name, self.name, len(self.option_value or ''))
class AlterUniqueTogether(AlterTogetherOptionOperation):
"""
Change the value of unique_together to the target one.
Input value of unique_together must be a set of tuples.
"""
option_name = 'unique_together'
def __init__(self, name, unique_together):
super().__init__(name, unique_together)
class AlterIndexTogether(AlterTogetherOptionOperation):
"""
Change the value of index_together to the target one.
Input value of index_together must be a set of tuples.
"""
option_name = "index_together"
def __init__(self, name, index_together):
super().__init__(name, index_together)
class AlterOrderWithRespectTo(ModelOptionOperation):
"""Represent a change with the order_with_respect_to option."""
option_name = 'order_with_respect_to'
def __init__(self, name, order_with_respect_to):
self.order_with_respect_to = order_with_respect_to
super().__init__(name)
def deconstruct(self):
kwargs = {
'name': self.name,
'order_with_respect_to': self.order_with_respect_to,
}
return (
self.__class__.__qualname__,
[],
kwargs
)
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
state.reload_model(app_label, self.name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
to_model = to_state.apps.get_model(app_label, self.name)
if self.allow_migrate_model(schema_editor.connection.alias, to_model):
from_model = from_state.apps.get_model(app_label, self.name)
# Remove a field if we need to
if from_model._meta.order_with_respect_to and not to_model._meta.order_with_respect_to:
schema_editor.remove_field(from_model, from_model._meta.get_field("_order"))
# Add a field if we need to (altering the column is untouched as
# it's likely a rename)
elif to_model._meta.order_with_respect_to and not from_model._meta.order_with_respect_to:
field = to_model._meta.get_field("_order")
if not field.has_default():
field.default = 0
schema_editor.add_field(
from_model,
field,
)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
self.database_forwards(app_label, schema_editor, from_state, to_state)
def references_field(self, model_name, name, app_label=None):
return (
self.references_model(model_name, app_label) and
(
self.order_with_respect_to is None or
name == self.order_with_respect_to
)
)
def describe(self):
return "Set order_with_respect_to on %s to %s" % (self.name, self.order_with_respect_to)
class AlterModelOptions(ModelOptionOperation):
"""
Set new model options that don't directly affect the database schema
(like verbose_name, permissions, ordering). Python code in migrations
may still need them.
"""
# Model options we want to compare and preserve in an AlterModelOptions op
ALTER_OPTION_KEYS = [
"base_manager_name",
"default_manager_name",
"default_related_name",
"get_latest_by",
"managed",
"ordering",
"permissions",
"default_permissions",
"select_on_save",
"verbose_name",
"verbose_name_plural",
]
def __init__(self, name, options):
self.options = options
super().__init__(name)
def deconstruct(self):
kwargs = {
'name': self.name,
'options': self.options,
}
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.name_lower]
model_state.options = {**model_state.options, **self.options}
for key in self.ALTER_OPTION_KEYS:
if key not in self.options:
model_state.options.pop(key, False)
state.reload_model(app_label, self.name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
pass
def database_backwards(self, app_label, schema_editor, from_state, to_state):
pass
def describe(self):
return "Change Meta options on %s" % self.name
class AlterModelManagers(ModelOptionOperation):
"""Alter the model's managers."""
serialization_expand_args = ['managers']
def __init__(self, name, managers):
self.managers = managers
super().__init__(name)
def deconstruct(self):
return (
self.__class__.__qualname__,
[self.name, self.managers],
{}
)
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.name_lower]
model_state.managers = list(self.managers)
state.reload_model(app_label, self.name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
pass
def database_backwards(self, app_label, schema_editor, from_state, to_state):
pass
def describe(self):
return "Change managers on %s" % self.name
class IndexOperation(Operation):
option_name = 'indexes'
@cached_property
def model_name_lower(self):
return self.model_name.lower()
class AddIndex(IndexOperation):
"""Add an index on a model."""
def __init__(self, model_name, index):
self.model_name = model_name
if not index.name:
raise ValueError(
"Indexes passed to AddIndex operations require a name "
"argument. %r doesn't have one." % index
)
self.index = index
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.model_name_lower]
model_state.options[self.option_name] = [*model_state.options[self.option_name], self.index.clone()]
state.reload_model(app_label, self.model_name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.add_index(model, self.index)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
model = from_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.remove_index(model, self.index)
def deconstruct(self):
kwargs = {
'model_name': self.model_name,
'index': self.index,
}
return (
self.__class__.__qualname__,
[],
kwargs,
)
def describe(self):
return 'Create index %s on field(s) %s of model %s' % (
self.index.name,
', '.join(self.index.fields),
self.model_name,
)
class RemoveIndex(IndexOperation):
"""Remove an index from a model."""
def __init__(self, model_name, name):
self.model_name = model_name
self.name = name
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.model_name_lower]
indexes = model_state.options[self.option_name]
model_state.options[self.option_name] = [idx for idx in indexes if idx.name != self.name]
state.reload_model(app_label, self.model_name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
model = from_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
from_model_state = from_state.models[app_label, self.model_name_lower]
index = from_model_state.get_index_by_name(self.name)
schema_editor.remove_index(model, index)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
to_model_state = to_state.models[app_label, self.model_name_lower]
index = to_model_state.get_index_by_name(self.name)
schema_editor.add_index(model, index)
def deconstruct(self):
kwargs = {
'model_name': self.model_name,
'name': self.name,
}
return (
self.__class__.__qualname__,
[],
kwargs,
)
def describe(self):
return 'Remove index %s from %s' % (self.name, self.model_name)
class AddConstraint(IndexOperation):
option_name = 'constraints'
def __init__(self, model_name, constraint):
self.model_name = model_name
self.constraint = constraint
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.model_name_lower]
model_state.options[self.option_name] = [*model_state.options[self.option_name], self.constraint]
state.reload_model(app_label, self.model_name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.add_constraint(model, self.constraint)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
schema_editor.remove_constraint(model, self.constraint)
def deconstruct(self):
return self.__class__.__name__, [], {
'model_name': self.model_name,
'constraint': self.constraint,
}
def describe(self):
return 'Create constraint %s on model %s' % (self.constraint.name, self.model_name)
class RemoveConstraint(IndexOperation):
option_name = 'constraints'
def __init__(self, model_name, name):
self.model_name = model_name
self.name = name
def state_forwards(self, app_label, state):
model_state = state.models[app_label, self.model_name_lower]
constraints = model_state.options[self.option_name]
model_state.options[self.option_name] = [c for c in constraints if c.name != self.name]
state.reload_model(app_label, self.model_name_lower, delay=True)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
from_model_state = from_state.models[app_label, self.model_name_lower]
constraint = from_model_state.get_constraint_by_name(self.name)
schema_editor.remove_constraint(model, constraint)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
model = to_state.apps.get_model(app_label, self.model_name)
if self.allow_migrate_model(schema_editor.connection.alias, model):
to_model_state = to_state.models[app_label, self.model_name_lower]
constraint = to_model_state.get_constraint_by_name(self.name)
schema_editor.add_constraint(model, constraint)
def deconstruct(self):
return self.__class__.__name__, [], {
'model_name': self.model_name,
'name': self.name,
}
def describe(self):
return 'Remove constraint %s from model %s' % (self.name, self.model_name)

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from django.db import router
from .base import Operation
class SeparateDatabaseAndState(Operation):
"""
Take two lists of operations - ones that will be used for the database,
and ones that will be used for the state change. This allows operations
that don't support state change to have it applied, or have operations
that affect the state or not the database, or so on.
"""
serialization_expand_args = ['database_operations', 'state_operations']
def __init__(self, database_operations=None, state_operations=None):
self.database_operations = database_operations or []
self.state_operations = state_operations or []
def deconstruct(self):
kwargs = {}
if self.database_operations:
kwargs['database_operations'] = self.database_operations
if self.state_operations:
kwargs['state_operations'] = self.state_operations
return (
self.__class__.__qualname__,
[],
kwargs
)
def state_forwards(self, app_label, state):
for state_operation in self.state_operations:
state_operation.state_forwards(app_label, state)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
# We calculate state separately in here since our state functions aren't useful
for database_operation in self.database_operations:
to_state = from_state.clone()
database_operation.state_forwards(app_label, to_state)
database_operation.database_forwards(app_label, schema_editor, from_state, to_state)
from_state = to_state
def database_backwards(self, app_label, schema_editor, from_state, to_state):
# We calculate state separately in here since our state functions aren't useful
to_states = {}
for dbop in self.database_operations:
to_states[dbop] = to_state
to_state = to_state.clone()
dbop.state_forwards(app_label, to_state)
# to_state now has the states of all the database_operations applied
# which is the from_state for the backwards migration of the last
# operation.
for database_operation in reversed(self.database_operations):
from_state = to_state
to_state = to_states[database_operation]
database_operation.database_backwards(app_label, schema_editor, from_state, to_state)
def describe(self):
return "Custom state/database change combination"
class RunSQL(Operation):
"""
Run some raw SQL. A reverse SQL statement may be provided.
Also accept a list of operations that represent the state change effected
by this SQL change, in case it's custom column/table creation/deletion.
"""
noop = ''
def __init__(self, sql, reverse_sql=None, state_operations=None, hints=None, elidable=False):
self.sql = sql
self.reverse_sql = reverse_sql
self.state_operations = state_operations or []
self.hints = hints or {}
self.elidable = elidable
def deconstruct(self):
kwargs = {
'sql': self.sql,
}
if self.reverse_sql is not None:
kwargs['reverse_sql'] = self.reverse_sql
if self.state_operations:
kwargs['state_operations'] = self.state_operations
if self.hints:
kwargs['hints'] = self.hints
return (
self.__class__.__qualname__,
[],
kwargs
)
@property
def reversible(self):
return self.reverse_sql is not None
def state_forwards(self, app_label, state):
for state_operation in self.state_operations:
state_operation.state_forwards(app_label, state)
def database_forwards(self, app_label, schema_editor, from_state, to_state):
if router.allow_migrate(schema_editor.connection.alias, app_label, **self.hints):
self._run_sql(schema_editor, self.sql)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
if self.reverse_sql is None:
raise NotImplementedError("You cannot reverse this operation")
if router.allow_migrate(schema_editor.connection.alias, app_label, **self.hints):
self._run_sql(schema_editor, self.reverse_sql)
def describe(self):
return "Raw SQL operation"
def _run_sql(self, schema_editor, sqls):
if isinstance(sqls, (list, tuple)):
for sql in sqls:
params = None
if isinstance(sql, (list, tuple)):
elements = len(sql)
if elements == 2:
sql, params = sql
else:
raise ValueError("Expected a 2-tuple but got %d" % elements)
schema_editor.execute(sql, params=params)
elif sqls != RunSQL.noop:
statements = schema_editor.connection.ops.prepare_sql_script(sqls)
for statement in statements:
schema_editor.execute(statement, params=None)
class RunPython(Operation):
"""
Run Python code in a context suitable for doing versioned ORM operations.
"""
reduces_to_sql = False
def __init__(self, code, reverse_code=None, atomic=None, hints=None, elidable=False):
self.atomic = atomic
# Forwards code
if not callable(code):
raise ValueError("RunPython must be supplied with a callable")
self.code = code
# Reverse code
if reverse_code is None:
self.reverse_code = None
else:
if not callable(reverse_code):
raise ValueError("RunPython must be supplied with callable arguments")
self.reverse_code = reverse_code
self.hints = hints or {}
self.elidable = elidable
def deconstruct(self):
kwargs = {
'code': self.code,
}
if self.reverse_code is not None:
kwargs['reverse_code'] = self.reverse_code
if self.atomic is not None:
kwargs['atomic'] = self.atomic
if self.hints:
kwargs['hints'] = self.hints
return (
self.__class__.__qualname__,
[],
kwargs
)
@property
def reversible(self):
return self.reverse_code is not None
def state_forwards(self, app_label, state):
# RunPython objects have no state effect. To add some, combine this
# with SeparateDatabaseAndState.
pass
def database_forwards(self, app_label, schema_editor, from_state, to_state):
# RunPython has access to all models. Ensure that all models are
# reloaded in case any are delayed.
from_state.clear_delayed_apps_cache()
if router.allow_migrate(schema_editor.connection.alias, app_label, **self.hints):
# We now execute the Python code in a context that contains a 'models'
# object, representing the versioned models as an app registry.
# We could try to override the global cache, but then people will still
# use direct imports, so we go with a documentation approach instead.
self.code(from_state.apps, schema_editor)
def database_backwards(self, app_label, schema_editor, from_state, to_state):
if self.reverse_code is None:
raise NotImplementedError("You cannot reverse this operation")
if router.allow_migrate(schema_editor.connection.alias, app_label, **self.hints):
self.reverse_code(from_state.apps, schema_editor)
def describe(self):
return "Raw Python operation"
@staticmethod
def noop(apps, schema_editor):
return None

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@@ -0,0 +1,53 @@
from collections import namedtuple
from django.db.models.fields.related import RECURSIVE_RELATIONSHIP_CONSTANT
def is_referenced_by_foreign_key(state, model_name_lower, field, field_name):
for state_app_label, state_model in state.models:
for _, f in state.models[state_app_label, state_model].fields:
if (f.related_model and
'%s.%s' % (state_app_label, model_name_lower) == f.related_model.lower() and
hasattr(f, 'to_fields')):
if (f.to_fields[0] is None and field.primary_key) or field_name in f.to_fields:
return True
return False
class ModelTuple(namedtuple('ModelTupleBase', ('app_label', 'model_name'))):
@classmethod
def from_model(cls, model, app_label=None, model_name=None):
"""
Take a model class or an 'app_label.ModelName' string and return a
ModelTuple('app_label', 'modelname'). The optional app_label and
model_name arguments are the defaults if "self" or "ModelName" are
passed.
"""
if isinstance(model, str):
if model == RECURSIVE_RELATIONSHIP_CONSTANT:
return cls(app_label, model_name)
if '.' in model:
return cls(*model.lower().split('.', 1))
return cls(app_label, model.lower())
return cls(model._meta.app_label, model._meta.model_name)
def __eq__(self, other):
if isinstance(other, ModelTuple):
# Consider ModelTuple equal if their model_name is equal and either
# one of them is missing an app_label.
return self.model_name == other.model_name and (
self.app_label is None or other.app_label is None or self.app_label == other.app_label
)
return super().__eq__(other)
def field_references_model(field, model_tuple):
"""Return whether or not field references model_tuple."""
remote_field = field.remote_field
if remote_field:
if ModelTuple.from_model(remote_field.model) == model_tuple:
return True
through = getattr(remote_field, 'through', None)
if through and ModelTuple.from_model(through) == model_tuple:
return True
return False