Dynamic fields in Django Admin

Question

I want to have additional fields regarding value of one field. Therefor I build a custom admin form to add some new fields.

Related to the blogpost of jacobian 1 thi

Answer 1

Maybe I am a bit late... However, I am using Django 3.0 and also wanted to dynamically ad some custom fields to the form, depending on the request.

I end up with a solution similar to the one described by @tehfink combined with @little_birdie.

However, just updating self.form.declared_fields as suggested didn't help. The result of this procedure is, that the list of custom fields defined in self.form.declared_fields always grows from request to request.

I solved this by initialising this dictionary first:

class ModelAdminGetCustomFieldsMixin(object):
    def get_fields(self, request, obj=None):
        fields = super().get_fields(request, obj=None)
        self.form.declared_fields = {}
        if obj:
            for custom_attribute in custom_attribute_list:
                self.form.declared_fields.update({custom_attribute.name: custom_attribute.field})
        return fields

where custom_attribute.field is a form field instance.

Additionally, it was required to define a ModelForm, wherein during initialisation the custom fields have been added dynamically as well:

class SomeModelForm(forms.ModelForm):

    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        for custom_attribute in custom_attribute_list:
            self.fields[custom_attribute.name] = custom_attribute.field

and use this ModelForm in the ModelAdmin.

Afterwards, the newly defined attributes can be used in, e.g., a fieldset.