Addition of css class on widget file input has no effect - django

Question

Try to add a css class into a forms.ImageField, has no effect.
model.py:-
class ProductImages(models.Model):
...
image_file_w200_png = models.ImageField(
verbose_name = "Imagens",
upload_to=upload_to_image_file_w200_png,
null=True,
blank=True,
default='magickhat-profile.jpg'
)
...
forms.py:-
class ProductImagesForm(ModelForm):
image_file_w200_png = forms.ImageField(widget=forms.FileInput(attrs={'class': 'image_add_product'}))
class Meta:
model = ProductImages
fields = ['image_file_w200_png']
That code has no effect, what is missing?
Edit:
admin.py
class UsersAdminSite(admin.AdminSite):
site_header = 'Painel Administrativo'
index_title = 'Painel Administrativo'
kadmin = UsersAdminSite(name='kadmin')
class AdminProductImages(admin.TabularInline):
model = ProductImages
extra = 1
max_num = 10
list_display = ('image_file_w200_png',)
fieldsets = (
(None, {'fields': ('image_file_w200_png',)}),
)
add_fieldsets = (
(None, {
'fields': ( 'image_file_w200_png'),
}),
)
kadmin.register(User, UserAdmin)
kadmin.register(Product, AdminProductModel)

Answer 1

Change the name of your image_file = forms.ImageField() to be image_file_w200_png. What you are doing there currently is defining a new field rather than changing your existing field because the names are not the same.
You could also define it in a different way in your class Meta: section. You can add a dictionary called widgets and write it like this:
class Meta:
model = ProductImages
fields = ['image_file_w200_png']
widgets = {'image_file_w200_png':forms.FileInput(attrs={'class':'image_add_product'})}
Edit:
The original poster was trying to add a css class to their admin.TabularInline class in their admin.py file. This can be done by using the same form definition above in my answer and specifying in the admin.TabularInline class what form is used. Example:
class ModelInline(admin.TabularInline):
model = #Model Class Name Here
form = #Form class Name Here