✨ [#2173] Define map background url on request

The map configuration can be edited at any moment. To make sure that we always return the correct map background url, we determined it per request.

src/openforms/formio/components/custom.py

@@ -14,7 +14,7 @@
 from rest_framework.request import Request
 
 from openforms.authentication.service import AuthAttribute
-from openforms.config.models import GlobalConfiguration
+from openforms.config.models import GlobalConfiguration, LeafletMapBackground
 from openforms.submissions.models import Submission
 from openforms.typing import DataMapping
 from openforms.utils.date import TIMEZONE_AMS, datetime_in_amsterdam, format_date_value
@@ -198,6 +198,16 @@ def rewrite_for_request(component, request: Request):
             component["initialCenter"]["lat"] = config.form_map_default_latitude
             component["initialCenter"]["lng"] = config.form_map_default_longitude
 
+        if component.get("backgroundIdentifier", False):
+            try:
+                leaflet_map_background = LeafletMapBackground.objects.get(
+                    identifier=component["backgroundIdentifier"]
+                )
+                # Write the background url information
+                component["url"] = leaflet_map_background.url
+            except LeafletMapBackground.DoesNotExist:
+                return None
+
     def build_serializer_field(self, component: Component) -> serializers.ListField:
         validate = component.get("validate", {})
         required = validate.get("required", False)