How do I call a model method in django ModelAdmin fieldsets?

Question

I want to display an embedded map on an admin form when data already exists in the db. I have the following code:

models.py

class Address(models.Model):
    address = models.CharField()

    def address_2_html(self):
        if self.address:
            # Return html for an embedded map using the entered address.
            return embedded_map_html
        else:
            return ''
    address_2_html.allow_tags = True

admin.py

class AddressAdmin(admin.ModelAdmin):
    fieldsets = [(label, {'fields': ['address','address_2_html']}),]

This doesn't work. I get an error:

'AddressAdmin.fieldsets[1][1]['fields']' refers to field 'address_2_html' that is missing from the form.

Another thing I tried was using the 'description' option for 'fieldsets', however, 'address_2_html' is not accessible within the scope of AddressAdmin. I did succeed at embedding a static map using 'description' which was cool but not cool enough.

Answer 1

Like that (from memory):

class AddressAdmin(admin.ModelAdmin):
    fieldsets = [(label, {'fields': ['address','address_2_html']}),]
    readonly_fields = ['address_2_html']

    def address_2_html(self, obj):
        return obj.address_2_html()
    address_2_html.allow_tags = True
    address_2_html.short_description = 'Address display'

Answer 2

Problem solved by overriding get_fieldsets() since the get_fieldsets() method allows access to the model object Address.

def get_fieldsets(self, request, obj=None):
    fs = [
        (self.label,  {'fields': ['address',]}),
        ('Map', {'fields': [], # required by django admin
                'description':obj.address_2_html(),
         }),
    ]
    return fs