Resize fields in Django Admin

You can set arbitrary HTML attributes on a widget using its "attrs" property.

You can do this in the Django admin using formfield_for_dbfield:

class MyModelAdmin(admin.ModelAdmin):
  def formfield_for_dbfield(self, db_field, **kwargs):
    field = super(ContentAdmin, self).formfield_for_dbfield(db_field, **kwargs)
    if db_field.name == 'somefield':
      field.widget.attrs['class'] = 'someclass ' + field.widget.attrs.get('class', '')
    return field

or with a custom Widget subclass and the formfield_overrides dictionary:

class DifferentlySizedTextarea(forms.Textarea):
  def __init__(self, *args, **kwargs):
    attrs = kwargs.setdefault('attrs', {})
    attrs.setdefault('cols', 80)
    attrs.setdefault('rows', 5)
    super(DifferentlySizedTextarea, self).__init__(*args, **kwargs)

class MyModelAdmin(admin.ModelAdmin):
  formfield_overrides = { models.TextField: {'widget': DifferentlySizedTextarea}}

You should use ModelAdmin.formfield_overrides.

It is quite easy - in admin.py, define:

from django.forms import TextInput, Textarea
from django.db import models

class YourModelAdmin(admin.ModelAdmin):
    formfield_overrides = {
        models.CharField: {'widget': TextInput(attrs={'size':'20'})},
        models.TextField: {'widget': Textarea(attrs={'rows':4, 'cols':40})},
    }

admin.site.register(YourModel, YourModelAdmin)