#29592: Error Migrate When Deleting Empty Model
-------------------------------------+-------------------------------------
Reporter: Jauhar | Owner: nobody
Arifin |
Type: Bug | Status: new
Component: | Version: 2.0
Migrations |
Severity: Normal | Keywords: migrations, sqlite
Triage Stage: | Has patch: 0
Unreviewed |
Needs documentation: 0 | Needs tests: 0
Patch needs improvement: 0 | Easy pickings: 0
UI/UX: 0 |
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Consider we have the following model:
{{{
class Animal(models.Model):
name = models.CharField("Name", max_length=256)
age = models.IntegerField("Age")
class Cat(Animal):
pass
class Dog(Animal):
pass
}}}
Lets say, Cat and Dog model don't have fields yet because we don't know
yet the requirements. We create migrations first to start working with
this simple model. But, someday we realize that Dog model is no longer
needed, so we need to delete it. The model became like this:
{{{
class Animal(models.Model):
name = models.CharField("Name", max_length=256)
age = models.IntegerField("Age")
class Cat(Animal):
pass
}}}
And then, we need to make migrations again. But, after make migrations, I
found that there is an error when migrating. The migrations strategy
somehow need to rename the table to myapp_dog__old, then create new table
myapp_dog, and then copy all records in myapp_dog__old to myapp_dog. It
raise error when using sqlite becase the SQL query looks like this:
{{{
INSERT INTO "myapp_dog" () SELECT FROM "myapp_dog__old"
}}}
This happens because dog model has no fields.
--
Ticket URL: <https://code.djangoproject.com/ticket/29592>
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