#27370: Django's Select widget adds a required="required" attribute, even if
created with empty_label=True
-------------------------------------+-------------------------------------
Reporter: alexpirine | Owner: Josef
Type: | Rousek
Cleanup/optimization | Status: closed
Component: Forms | Version: master
Severity: Normal | Resolution: fixed
Keywords: | Triage Stage: Ready for
HTML,Select,wdiget,ModelChoiceField| checkin
Has patch: 1 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
-------------------------------------+-------------------------------------
Comment (by Aurélien Pardon):
There is a huge performance regression as a side-effect of
[changeset:"aaecf038cae61f114db396f74e06759c95f21e93" aaecf038]. For
{{{ModelChoiceField}}} with {{{empty_label=None}}}, it doubles the queries
to the database.
With this {{{simple_app/models.py}}}:
{{{#!python
from django.db import models
class MyModel(models.Model):
my_field = models.CharField(max_length=1)
}}}
the following code:
{{{#!python
from django import forms
from simple_app.models import MyModel
class MyForm(forms.Form):
my_form_field = forms.ModelChoiceField(MyModel.objects.all(),
empty_label=None)
MyForm().as_ul()
}}}
makes two times the same request to the database:
{{{#!python
>>> from django.db import connection
>>> from django.db import reset_queries
>>> reset_queries()
>>> _ = MyForm().as_ul()
>>> connection.queries
[{'sql': 'SELECT "simple_app_mymodel"."id",
"simple_app_mymodel"."my_field" FROM "simple_app_mymodel"',
'time': '0.000'},
{'sql': 'SELECT "simple_app_mymodel"."id",
"simple_app_mymodel"."my_field" FROM "simple_app_mymodel"',
'time': '0.000'}]
}}}
Before this commit, it only makes one request (as intended IMO):
{{{#!python
>>> from django.db import connection
>>> from django.db import reset_queries
>>> reset_queries()
>>> _ = MyForm().as_ul()
>>> connection.queries
[{'sql': 'SELECT "simple_app_mymodel"."id",
"simple_app_mymodel"."my_field" FROM "simple_app_mymodel"',
'time': '0.000'}]
}}}
--
Ticket URL: <https://code.djangoproject.com/ticket/27370#comment:15>
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