Better json management

source/ap/activity_stream.d

@@ -9,10 +9,13 @@ import util;
  * https://www.w3.org/TR/activitypub/#obj
  +/
 class ASObject {
+  // Required fields (for root objects)
   string context; /// Must be activitystream context
   string id; /// AP requirement for unique identifier
   string type; /// AP requirement for type of object
 
+  // Optional fields
+
   JSONValue raw;
 
   /++ 
@@ -25,24 +28,23 @@ class ASObject {
     with (this) {
       const(JSONValue)* ascontext = "@context" in json;
 
-      if (ascontext == null)
-        throw new Exception("No context in ActivityStream Object");
+      if (ascontext) {
+        switch ((*ascontext).type) {
+        case JSONType.ARRAY:
+          context = (*ascontext)[0].str;
+          break;
 
-      switch ((*ascontext).type) {
-      case JSONType.ARRAY:
-        context = (*ascontext)[0].str;
-        break;
+        case JSONType.STRING:
+          context = (*ascontext).str;
+          break;
 
-      case JSONType.STRING:
-        context = (*ascontext).str;
-        break;
-
-      default:
-        throw new Exception("Invalid @context type for ActivityStream Object");
+        default:
+          throw new Exception("Invalid @context type for ActivityStream Object");
+        }
       }
 
-      id = json.requiredKey!"id".str;
-      type = json.requiredKey!"type".str;
+      optional(json, "id", id);
+      optional(json, "type", type);
 
       raw = json;
     }