#35882: Loop on all errors in `InteractiveMigrationQuestioner._ask_default()`
-------------------------------------+-------------------------------------
Reporter: Adam Johnson | Type:
| Cleanup/optimization
Status: new | Component:
| Migrations
Version: dev | Severity: Normal
Keywords: | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
When changing some fields, the migration questioner can ask for new field
default values entered through a Python prompt.
Yesterday, I made a typo which made the makemigrations process exit. This
was a little frustrating as there were several fields to fix, and my work
answering for the first fields was lost.
Currently, the questioner loops on `SyntaxError` and `NameError`
([https://github.com/django/django/blob/1feedc8ef8a34484cb5afe33f5c45b543b860210/django/db/migrations/questioner.py#L163
source]). My mistake lead to an `AttributeError`, hence the crash and
lost work. I propose we extend this clause to `Exception` - there's little
harm in displaying the error and looping.
Here's a reproducing example. Say you drop `null=True` from two model
fields:
{{{#!diff
diff --git example/models.py example/models.py
index 816fe37..9743877 100644
--- example/models.py
+++ example/models.py
@@ -2,5 +2,5 @@
class Book(models.Model):
- title = models.CharField(max_length=100, null=True)
- published_date = models.DateField(null=True)
+ title = models.CharField(max_length=100)
+ published_date = models.DateField()
}}}
`makemigrations` asks you about the first one:
{{{
$ ./manage.py makemigrations example
It is impossible to change a nullable field 'title' on book to non-
nullable without providing a default. This is because the database needs
something to populate existing rows.
Please select a fix:
1) Provide a one-off default now (will be set on all existing rows with a
null value for this column)
2) Ignore for now. Existing rows that contain NULL values will have to be
handled manually, for example with a RunPython or RunSQL operation.
3) Quit and manually define a default value in models.py.
Select an option: 1
Please enter the default value as valid Python.
The datetime and django.utils.timezone modules are available, so it is
possible to provide e.g. timezone.now as a value.
Type 'exit' to exit this prompt
>>> "Unknown book"
}}}
Immediately after this, it asks about the second field. Making a typo like
`.dat()` instead of `.date()` crashes the process:
{{{
It is impossible to change a nullable field 'published_date' on book to
non-nullable without providing a default. This is because the database
needs something to populate existing rows.
Please select a fix:
1) Provide a one-off default now (will be set on all existing rows with a
null value for this column)
2) Ignore for now. Existing rows that contain NULL values will have to be
handled manually, for example with a RunPython or RunSQL operation.
3) Quit and manually define a default value in models.py.
Select an option: 1
Please enter the default value as valid Python.
The datetime and django.utils.timezone modules are available, so it is
possible to provide e.g. timezone.now as a value.
Type 'exit' to exit this prompt
>>> datetime.dat(1970, 1, 1)
Traceback (most recent call last):
File "/..././manage.py", line 21, in <module>
main()
...
File "/.../.venv/.../django/db/migrations/questioner.py", line 162, in
_ask_default
return eval(code, {}, {"datetime": datetime, "timezone": timezone})
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "<string>", line 1, in <module>
AttributeError: module 'datetime' has no attribute 'dat'. Did you mean:
'date'?
}}}
But if you instead made a typo in the `datetime` name, it would loop:
{{{
>>> datetme.date(1970,1,1)
Invalid input: name 'datetme' is not defined
>>>
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/35882>
Django <https://code.djangoproject.com/>
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