Django Admin - Overriding the widget of a custom form field

Try to change your field like this:

class TagField(forms.CharField):
    def __init__(self, *args, **kwargs):
        self.widget = forms.TextInput(attrs={'class':'tag_field'})
        super(TagField, self).__init__(*args, **kwargs)

This would allow to use the widget which comes from **kwargs. Otherwise your field will always use form.TextInput widget.

You can override field widgets by extending ModelForm Meta class since Django 1.2:

class ProductAdminForm(forms.ModelForm):
    class Meta:
        model = Product
        widgets = {
            'tags': admin.widgets.AdminTextareaWidget
        }

class ProductAdmin(admin.ModelAdmin):
    form = ProductAdminForm

https://docs.djangoproject.com/en/dev/topics/forms/modelforms/#overriding-the-default-fields

For a specific field not a kind of fields I use:

Django 2.1.7

class ProjectAdminForm(forms.ModelForm):
    class Meta:
        model = Project
        fields = '__all__'
        widgets = {
            'project_description': forms.Textarea(attrs={'cols': 98})
        }

class ProjectAdmin(admin.ModelAdmin):
    form = ProjectAdminForm

Thanks, @Murat Çorlu

The django admin uses custom widgets for many of its fields. The way to override fields is to create a Form for use with the ModelAdmin object.

# forms.py

from django import forms
from django.contrib import admin

class ProductAdminForm(forms.ModelForm):
    def __init__(self, *args, **kwargs):
        super(ProductAdminForm, self).__init__(*args, **kwargs)
        self.fields['tags'].widget = admin.widgets.AdminTextareaWidget()

Then, in your ModelAdmin object, you specify the form:

from django.contrib import admin
from models import Product
from forms import ProductAdminForm

class ProductAdmin(admin.ModelAdmin):
    form = ProductAdminForm

admin.site.register(Product, ProductAdmin)

You can also override the queryset at this time: to filter objects according to another field in the model, for instance (since limit_choices_to cannot handle this)