django1/django/db/migrations/operations/fields.py

51 lines
2.0 KiB
Python

from .base import Operation
class AddField(Operation):
"""
Adds a field to a model.
"""
def __init__(self, model_name, name, instance):
self.model_name = model_name
self.name = name
self.instance = instance
def state_forwards(self, app_label, state):
state.models[app_label, self.model_name.lower()].fields.append((self.name, self.instance))
def database_forwards(self, app_label, schema_editor, from_state, to_state):
from_model = from_state.render().get_model(app_label, self.model_name)
to_model = to_state.render().get_model(app_label, self.model_name)
schema_editor.add_field(from_model, to_model._meta.get_field_by_name(self.name)[0])
def database_backwards(self, app_label, schema_editor, from_state, to_state):
from_model = from_state.render().get_model(app_label, self.model_name)
schema_editor.remove_field(from_model, from_model._meta.get_field_by_name(self.name)[0])
class RemoveField(Operation):
"""
Removes a field from a model.
"""
def __init__(self, model_name, name):
self.model_name = model_name
self.name = name
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
def database_forwards(self, app_label, schema_editor, from_state, to_state):
from_model = from_state.render().get_model(app_label, self.model_name)
schema_editor.remove_field(from_model, from_model._meta.get_field_by_name(self.name)[0])
def database_backwards(self, app_label, schema_editor, from_state, to_state):
from_model = from_state.render().get_model(app_label, self.model_name)
to_model = to_state.render().get_model(app_label, self.model_name)
schema_editor.add_field(from_model, to_model._meta.get_field_by_name(self.name)[0])