from __future__ import unicode_literals
from django.db.models.fields import NOT_PROVIDED
from django.utils import six
from django.utils.functional import cached_property
from .base import Operation
[docs]class AddField(Operation):
"""
Adds a field to a model.
"""
def __init__(self, model_name, name, field, preserve_default=True):
self.model_name = model_name
self.name = name
self.field = field
self.preserve_default = preserve_default
@cached_property
def name_lower(self):
return self.name.lower()
@cached_property
def model_name_lower(self):
return self.model_name.lower()
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))
state.reload_model(app_label, self.model_name_lower)
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 references_model(self, name, app_label=None):
return name.lower() == self.model_name_lower
def references_field(self, model_name, name, app_label=None):
return self.references_model(model_name) and name.lower() == self.name_lower
[docs]class RemoveField(Operation):
"""
Removes a field from a model.
"""
def __init__(self, model_name, name):
self.model_name = model_name
self.name = name
@cached_property
def name_lower(self):
return self.name.lower()
@cached_property
def model_name_lower(self):
return self.model_name.lower()
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 = []
for name, instance in state.models[app_label, self.model_name_lower].fields:
if name != self.name:
new_fields.append((name, instance))
state.models[app_label, self.model_name_lower].fields = new_fields
state.reload_model(app_label, self.model_name_lower)
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 references_model(self, name, app_label=None):
return name.lower() == self.model_name_lower
def references_field(self, model_name, name, app_label=None):
return self.references_model(model_name) and name.lower() == self.name_lower
[docs]class AlterField(Operation):
"""
Alters 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.model_name = model_name
self.name = name
self.field = field
self.preserve_default = preserve_default
@cached_property
def name_lower(self):
return self.name.lower()
@cached_property
def model_name_lower(self):
return self.model_name.lower()
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
]
state.reload_model(app_label, self.model_name_lower)
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 the field is a relatedfield with an unresolved rel.to, just
# set it equal to the other field side. Bandaid fix for AlterField
# migrations that are part of a RenameModel change.
if from_field.rel and from_field.rel.to:
if isinstance(from_field.rel.to, six.string_types):
from_field.rel.to = to_field.rel.to
elif to_field.rel and isinstance(to_field.rel.to, six.string_types):
to_field.rel.to = from_field.rel.to
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 references_model(self, name, app_label=None):
return name.lower() == self.model_name_lower
def references_field(self, model_name, name, app_label=None):
return self.references_model(model_name) and name.lower() == self.name_lower
[docs]class RenameField(Operation):
"""
Renames a field on the model. Might affect db_column too.
"""
def __init__(self, model_name, old_name, new_name):
self.model_name = model_name
self.old_name = old_name
self.new_name = new_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()
@cached_property
def model_name_lower(self):
return self.model_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):
# Rename the field
state.models[app_label, self.model_name_lower].fields = [
(self.new_name if n == self.old_name else n, f)
for n, f in state.models[app_label, self.model_name_lower].fields
]
# Fix index/unique_together to refer to the new field
options = state.models[app_label, self.model_name_lower].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]
]
state.reload_model(app_label, self.model_name_lower)
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_model(self, name, app_label=None):
return name.lower() == self.model_name_lower
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
)
Mar 06, 2018