Make ppoi updatable

program/serializers.py

@@ -198,6 +198,7 @@ class HostLinkSerializer(serializers.ModelSerializer):
 
 
 class ImageSerializer(serializers.ModelSerializer):
+    ppoi = serializers.CharField(max_length=20)  # PPOIField max_length
     thumbnails = serializers.SerializerMethodField()
 
     @staticmethod
@@ -216,7 +217,6 @@ class ImageSerializer(serializers.ModelSerializer):
         read_only_fields = (
             "height",
             "id",
-            "ppoi",
             "thumbnails",
             "width",
         )
@@ -224,6 +224,7 @@ class ImageSerializer(serializers.ModelSerializer):
             "alt_text",
             "credits",
             "image",
+            "ppoi",
         ) + read_only_fields
 
     def create(self, validated_data):
@@ -237,9 +238,10 @@ class ImageSerializer(serializers.ModelSerializer):
     def update(self, instance, validated_data):
         """Update and return an existing Image instance, given the validated data."""
 
-        # Only alt_text and credits can be updated.
+        # Only these fields can be updated.
         instance.alt_text = validated_data.get("alt_text", instance.alt_text)
         instance.credits = validated_data.get("credits", instance.credits)
+        instance.image.ppoi = validated_data.get("ppoi", instance.ppoi)
 
         instance.save()