#24282: Cannot Modify Foreign Keys Within Data Migrations
---------------------------------+-------------------------------------
Reporter: jeffasinger | Owner:
Type: Bug | Status: new
Component: Migrations | Version: 1.8alpha1
Severity: Release blocker | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
---------------------------------+-------------------------------------
Comment (by jeffasinger):
I've created a test that fails.
It creates two models, in two seperate apps, and then alters the one with
a ForeignKey pointing at it before running the DataMigration.
{{{
def inner_method(models, schema_editor):
Author = models.get_model("test_authors", "Author")
Book = models.get_model("test_books", "Book")
author = Author.objects.create(name="Hemingway")
book = Book("Old Man and The Sea")
book.author = author
create_author = migrations.CreateModel(
"Author",
[
("id", models.AutoField(primary_key=True)),
("name", models.CharField(max_length=100)),
],
options={},
)
create_book = migrations.CreateModel(
"Book",
[
("id", models.AutoField(primary_key=True)),
("title", models.CharField(max_length=100)),
("author", models.ForeignKey("test_authors.Author"))
],
options={},
)
add_hometown = migrations.AddField(
"Author",
"hometown",
models.CharField(max_length=100),
)
create_old_man = migrations.RunPython(
inner_method, inner_method
)
project_state = ProjectState()
with connection.schema_editor() as editor:
new_state = project_state.clone()
create_author.state_forwards("test_authors", new_state)
create_author.database_forwards("test_authors", editor,
project_state, new_state)
project_state, new_state = new_state, new_state.clone()
create_book.state_forwards("test_books", new_state)
create_book.database_forwards("test_books", editor, project_state,
new_state)
project_state, new_state = new_state, new_state.clone()
add_hometown.state_forwards("test_authors", new_state)
add_hometown.database_forwards("test_authors", editor,
project_state, new_state)
project_state, new_state = new_state, new_state.clone()
create_old_man.state_forwards("test_books", new_state)
create_old_man.database_forwards("test_books", editor,
project_state, new_state)
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/24282#comment:9>
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