#34260: models.FloatField documentation doesn't mention that +inf, -inf, and NaN
are invalid.
-------------------------------------+-------------------------------------
Reporter: Matt Cooper | Owner: nobody
Type: | Status: new
Cleanup/optimization |
Component: Documentation | Version: 4.1
Severity: Normal | Resolution:
Keywords: floatfield | Triage Stage:
| Unreviewed
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 1 | UI/UX: 0
-------------------------------------+-------------------------------------
Changes (by Matt Cooper):
* status: closed => new
* resolution: invalid =>
Comment:
Ah, I made two mistakes in my research, covered below.
I believe a scoped-down version of this proposed change is valid, because
`float('nan')` is considered "null" (at least on SQLite). This is not
obvious, and much like the "empty string vs null" discussion in CharField,
would have helped me. The infinities do seem to work properly, so as
mentioned above, this must be database-dependent.
In that test case, is the field `null=True`? In a brand new Django 4.1
project with the following `models.py` pointing to a SQLite database:
{{{#!python
from django.db import models
class Example(models.Model):
nullable_float = models.FloatField(null=True)
nonnullable_float = models.FloatField()
}}}
then I get the following in `./manage.py shell`:
{{{#!python
>>> from repro.models import Example
>>> e1 = Example(nullable_float=1.0, nonnullable_float=2.0)
>>> e2 = Example(nullable_float=float('nan'), nonnullable_float=2.0)
>>> e3 = Example(nullable_float=1.0, nonnullable_float=float('nan'))
>>> e1.save()
>>> e2.save()
>>> e3.save()
Traceback (most recent call last):
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-
packages/django/db/backends/utils.py", line 89, in _execute
return self.cursor.execute(sql, params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-
packages/django/db/backends/sqlite3/base.py", line 357, in execute
return Database.Cursor.execute(self, query, params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
sqlite3.IntegrityError: NOT NULL constraint failed:
repro_example.nonnullable_float
The above exception was the direct cause of the following exception:
Traceback (most recent call last):
File "<console>", line 1, in <module>
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-packages/django/db/models/base.py",
line 812, in save
self.save_base(
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-packages/django/db/models/base.py",
line 863, in save_base
updated = self._save_table(
^^^^^^^^^^^^^^^^^
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-packages/django/db/models/base.py",
line 1006, in _save_table
results = self._do_insert(
^^^^^^^^^^^^^^^^
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-packages/django/db/models/base.py",
line 1047, in _do_insert
return manager._insert(
^^^^^^^^^^^^^^^^
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-
packages/django/db/models/manager.py", line 85, in manager_method
return getattr(self.get_queryset(), name)(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-packages/django/db/models/query.py",
line 1791, in _insert
return query.get_compiler(using=using).execute_sql(returning_fields)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-
packages/django/db/models/sql/compiler.py", line 1660, in execute_sql
cursor.execute(sql, params)
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-
packages/django/db/backends/utils.py", line 103, in execute
return super().execute(sql, params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-
packages/django/db/backends/utils.py", line 67, in execute
return self._execute_with_wrappers(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-
packages/django/db/backends/utils.py", line 80, in _execute_with_wrappers
return executor(sql, params, many, context)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-
packages/django/db/backends/utils.py", line 84, in _execute
with self.db.wrap_database_errors:
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-packages/django/db/utils.py", line
91, in __exit__
raise dj_exc_value.with_traceback(traceback) from exc_value
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-
packages/django/db/backends/utils.py", line 89, in _execute
return self.cursor.execute(sql, params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/Users/vtbassmatt/Library/Caches/pypoetry/virtualenvs/django34260
-KHbD0UBT-py3.11/lib/python3.11/site-
packages/django/db/backends/sqlite3/base.py", line 357, in execute
return Database.Cursor.execute(self, query, params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
django.db.utils.IntegrityError: NOT NULL constraint failed:
repro_example.nonnullable_float
}}}
And for completeness, my mistakes:
1. I was looking at the `FloatField` code for forms, not models, because I
searched `FloatField` and didn't pay close enough attention. See
https://github.com/django/django/blob/0fbdb9784da915fce5dcc1fe82bac9b4785749e5/django/forms/fields.py#L370.
2. I had only tested `float('nan')` myself. Once I made the above search
error, I assumed that `float('inf')` would behave identically, but didn't
test it since I wanted to get back to my task at hand.
--
Ticket URL: <https://code.djangoproject.com/ticket/34260#comment:4>
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