Readonly method for field in Django admin interface is never called

Question

The Django Docs state that you can output custom HTML for readonly fields in the admin interface. This is exactly what I need, but it does not seem to work.

In admin.py:

from django.contrib import admin

class ExampleAdmin(admin.ModelAdmin):
    readonly_fields = ('myfield', )

    def myfield(self, instance):
        print 'This part of the code is never reached!'
        return u'<b>My custom html for the readonly field!</b>'

    myfield.allow_tags = True

admin.site.register(State, StateAdmin)

In models.py:

class State(models.Model):
    myfield = MyCustomField()
    ... etc ...

class MyCustomField(models.TextField):
    def to_python(self, value):
        ... etc ...

The field is displayed as read-only on the admin edit page. However, the 'myfield' method that is supposed to create custom html is never called.

Does anybody know what I'm doing wrong?

Kind regards,

Patrick

Answer 1

Looking at the "django/contrib/admin/util.py" file's lookup_field method, this appears to be the expected behavior. Here is the code you're using:

readonly_fields = ('myfield', )

Since myfield is an actual field defined in your model, having it in readonly_fields will only make it non-editable; it will not allow you to customize what gets displayed to the user. In order to do that, you have to give readonly_fields something that isn't an actual field, like myfield_readonly. You will then have to rename your ModelAdmin's myfield method to myfield_readonly, of course, as well as the myfield.allow_tags = True. You'll probably also want to add myfield_readonly.short_description = 'My Field'. Lastly, you'll want to leave the actual myfield field out of the form using either exclude or fields.