Add object interceptor API to allow missing model and missing my-items handling (#3522)

* Extends Object API to allow adding interceptors

Co-authored-by: Andrew Henry <akhenry@gmail.com>

src/api/objects/ObjectAPI.js

@@ -26,6 +26,7 @@ define([
     './MutableObject',
     './RootRegistry',
     './RootObjectProvider',
+    './InterceptorRegistry',
     'EventEmitter'
 ], function (
     _,
@@ -33,6 +34,7 @@ define([
     MutableObject,
     RootRegistry,
     RootObjectProvider,
+    InterceptorRegistry,
     EventEmitter
 ) {
 
@@ -48,6 +50,7 @@ define([
         this.rootRegistry = new RootRegistry();
         this.rootProvider = new RootObjectProvider.default(this.rootRegistry);
         this.cache = {};
+        this.interceptorRegistry = new InterceptorRegistry.default();
     }
 
     /**
@@ -177,6 +180,10 @@ define([
 
         return objectPromise.then(result => {
             delete this.cache[keystring];
+            const interceptors = this.listGetInterceptors(identifier, result);
+            interceptors.forEach(interceptor => {
+                result = interceptor.invoke(identifier, result);
+            });
 
             return result;
         });
@@ -312,6 +319,27 @@ define([
         });
     };
 
+    /**
+     * Register an object interceptor that transforms a domain object requested via module:openmct.ObjectAPI.get
+     * The domain object will be transformed after it is retrieved from the persistence store
+     * The domain object will be transformed only if the interceptor is applicable to that domain object as defined by the InterceptorDef
+     *
+     * @param {module:openmct.InterceptorDef} interceptorDef the interceptor definition to add
+     * @method addGetInterceptor
+     * @memberof module:openmct.InterceptorRegistry#
+     */
+    ObjectAPI.prototype.addGetInterceptor = function (interceptorDef) {
+        this.interceptorRegistry.addInterceptor(interceptorDef);
+    };
+
+    /**
+     * Retrieve the interceptors for a given domain object.
+     * @private
+     */
+    ObjectAPI.prototype.listGetInterceptors = function (identifier, object) {
+        return this.interceptorRegistry.getInterceptors(identifier, object);
+    };
+
     /**
      * Uniquely identifies a domain object.
      *