title: Django-admin: Changing field values in change form before rendering
body: <p>There's a link in custom view that points to Django-admin change form of specific model instance. The goal is to change values of some form fields before form rendering, like it's possible to prepopulate fields in add form by adding parameters (ModelFieldName=value) to add form URL. How to change values in change form fields before rendering? Maybe, I must create my ModelForm, change fields values in it and assign to form variable of ModelAdmin? If so, how to change values of ModelForm fields?</p>