Hidden field in TabularInline breaks table layout

[yliharma]

Defining a hidden field in a ModelForm used within a TabularInline breaks the table layout (see screenshot tabular.png): the hidden field label is not present in the <thead> table tag but there is a corresponding <td> tag containing the actual input, resulting in a different number of table columns which breaks the table completely.

# models.py
from django.db import models

class FirstModel(models.Model):
    a_field = models.CharField(max_length=10)

class SecondModel(models.Model):
    first_fk = models.ForeignKey(FirstModel)
    b_field = models.CharField(max_length=10)
    c_field = models.CharField(max_length=10)

# forms.py
from django import forms
from dummy.inline_test import models

class SecondForm(forms.ModelForm):
    b_field = forms.CharField(widget=forms.HiddenInput, required=True)

    class Meta:
        model = models.SecondModel

# admin.py
from django.contrib import admin
from dummy.inline_test import models, forms

class SecondAdmin(admin.TabularInline):
    model = models.SecondModel
    form = forms.SecondForm
    extra = 3

class FirstAdmin(admin.ModelAdmin):
    inlines = [SecondAdmin]
 
admin.site.register(models.FirstModel, FirstAdmin)

[yliharma]

TabularInline with hidden field

[Claude Paroz]

Fixed in #18263 (will be in 1.7).