fix(coap-server): add forms to affordances in a more type-safe way

Author: JKRhb

packages/binding-coap/src/coap-server.ts

@@ -32,14 +32,16 @@ import { Server, createServer, registerFormat, IncomingMessage, OutgoingMessage
 import slugify from "slugify";
 import { Readable } from "stream";
 import { MdnsIntroducer } from "./mdns-introducer";
-import { PropertyElement, DataSchema } from "wot-thing-description-types";
+import { PropertyElement, DataSchema, ActionElement, EventElement } from "wot-thing-description-types";
 import { CoapServerConfig } from "./coap";
 import { DataSchemaValue } from "wot-typescript-definitions";
 
 const { debug, warn, info, error } = createLoggers("binding-coap", "coap-server");
 
 type CoreLinkFormatParameters = Map<string, string[] | number[]>;
 
+type AffordanceElement = PropertyElement | ActionElement | EventElement;
+
 // TODO: Move to core?
 type AugmentedInteractionOptions = WoT.InteractionOptions & { formIndex: number };
 
@@ -228,6 +230,15 @@ export default class CoapServer implements ProtocolServer {
         return opValues;
     }
 
+    private addFormToAffordance(form: TD.Form, affordance: AffordanceElement): void {
+        const affordanceForms = affordance.forms;
+        if (affordanceForms == null) {
+            affordance.forms ??= [form];
+        } else {
+            affordanceForms.push(form);
+        }
+    }
+
     private fillInPropertyBindingData(thing: ExposedThing, base: string, offeredMediaType: string) {
         for (const [propertyName, property] of Object.entries(thing.properties)) {
             const opValues = ProtocolHelpers.getPropertyOpValues(property);
@@ -241,7 +252,7 @@ export default class CoapServer implements ProtocolServer {
                 property.uriVariables
             );
 
-            property.forms.push(form);
+            this.addFormToAffordance(form, property);
             this.logHrefAssignment(form, "Property", propertyName);
         }
     }
@@ -258,7 +269,7 @@ export default class CoapServer implements ProtocolServer {
                 action.uriVariables
             );
 
-            action.forms.push(form);
+            this.addFormToAffordance(form, action);
             this.logHrefAssignment(form, "Action", actionName);
         }
     }
@@ -275,7 +286,7 @@ export default class CoapServer implements ProtocolServer {
                 event.uriVariables
             );
 
-            event.forms.push(form);
+            this.addFormToAffordance(form, event);
             this.logHrefAssignment(form, "Event", eventName);
         }
     }