id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
35449	SplitArrayField doesn't validate properly with remove_trailing_nulls=True	Matthijs	Calvin Vu	"I created an {{{ArrayField(models.CharField(), size=3)}}} on one of my models and created a form for it using the {{{SplitArrayField}}}. My requirements where that the array field was optional to fill in and that you could also just fill in one of the CharFields and leave the others blank. So according to [https://docs.djangoproject.com/en/4.2/ref/contrib/postgres/forms/#django.contrib.postgres.forms.SplitArrayField.remove_trailing_nulls the docs] I was to set the {{{CharField}}} in my {{{SplitArrayField}}} to {{{required=True}}} and {{{remove_trailing_nulls=True}}} on the {{{SplitArrayField}}}.
{{{
SplitArrayField(
    forms.CharField(required=True, max_length=148),
    size=3,
    widget=SplitArrayWidget(forms.TextInput(attrs={'size': '148'}), 3),
    remove_trailing_nulls=True,
    required=False
)
}}}

To my surprise the form did not validate properly and I was able to submit inputs that exceeded the {{{max_length}}} specified in my form.
Looking at the {{{def clean}}} method of the {{{SplitArrayField}}} I suspect a problem there.

{{{
try:
    cleaned_data.append(self.base_field.clean(item))
except ValidationError as error:
    errors.append(
        prefix_validation_error(
            error,
            self.error_messages[""item_invalid""],
            code=""item_invalid"",
            params={""nth"": index + 1},
        )
    )
    cleaned_data.append(None)
    ...
}}}

If there is any {{{ValidationError}}} the error is added to {{{errors}}}, at the same time {{{None}}} is appended to the {{{cleaned_data}}}.
This causes issues with the {{{self._remove_trailing_nulls}}} later on.

{{{
cleaned_data, null_index = self._remove_trailing_nulls(cleaned_data)
if null_index is not None:
    errors = errors[:null_index]
errors = list(filter(None, errors))
}}}

{{{cleaned_data}}} is passed to {{{self._remove_trailing_nulls}}} and because {{{remove_trailing_nulls=True}}}, {{{null_index}}} will be {{{0}}} thus {{{errors}}} is reassigned to an empty list.

I wrote a test case showcasing this issue:
{{{
from django import forms
from django.contrib.postgres.forms import SplitArrayField

class TestForm1(forms.Form):
    field = SplitArrayField(
        forms.CharField(max_length=5, required=True),
        size=3,
        remove_trailing_nulls=True,
        required=False,
    )

class TestForm2(forms.Form):
    field = forms.CharField(max_length=5, required=True)

class SplitArrayFieldTest(TestCase):
    def test_validation_error(self):
        invalid_value = 'invalid'
        form1 = TestForm1(data={'field': [invalid_value, '', '']})
        form2 = TestForm2(data={'field': invalid_value})

        self.assertFalse(form1.is_valid())  #is_valid() should return False, but returns True
        self.assertFalse(form2.is_valid())
}}}"	Bug	closed	contrib.postgres	4.2	Normal	fixed		Calvin Vu	Ready for checkin	1	0	0	0	0	0