Add null and undefined type coercion for query params

packages/ember-routing/lib/system/route.js

@@ -848,7 +848,10 @@ let Route = EmberObject.extend(ActionHandler, Evented, {
         } else {
           if (presentKey) {
             svalue = params[presentKey];
-            value = route.deserializeQueryParam(svalue, qp.urlKey, qp.type);
+
+            if (svalue !== undefined) {
+              value = route.deserializeQueryParam(svalue, qp.urlKey, qp.type);
+            }
           } else {
             // No QP provided; use default value.
             svalue = qp.serializedDefaultValue;

packages/ember-routing/lib/system/router.js

@@ -701,7 +701,9 @@ const EmberRouter = EmberObject.extend(Evented, {
     @param {String} type
   */
   _serializeQueryParam(value, type) {
-    if (type === 'array') {
+    if (value === null || value === undefined) {
+      return value;
+    } else if (type === 'array') {
       return JSON.stringify(value);
     }
 
@@ -737,7 +739,9 @@ const EmberRouter = EmberObject.extend(Evented, {
     @param {String} defaultType
   */
   _deserializeQueryParam(value, defaultType) {
-    if (defaultType === 'boolean') {
+    if (value === null || value === undefined) {
+      return value;
+    } else if (defaultType === 'boolean') {
       return value === 'true';
     } else if (defaultType === 'number') {
       return (Number(value)).valueOf();

packages/ember/tests/routing/query_params_test.js

@@ -1153,6 +1153,60 @@ moduleFor('Query Params - main', class extends QueryParamTestCase {
     });
   }
 
+  ['@test Setting bound query param property to null or undefined does not serialize to url'](assert) {
+    assert.expect(9);
+
+    this.router.map(function() {
+      this.route('home');
+    });
+
+    this.setSingleQPController('home', 'foo', [1, 2]);
+
+    return this.visitAndAssert('/home').then(() => {
+      var controller = this.getController('home');
+
+      assert.deepEqual(controller.get('foo'), [1,2]);
+      this.assertCurrentPath('/home');
+
+      this.setAndFlush(controller, 'foo', emberA([1,3]));
+      this.assertCurrentPath('/home?foo=%5B1%2C3%5D');
+
+      return this.transitionTo('/home').then(() => {
+        assert.deepEqual(controller.get('foo'), [1,2]);
+        this.assertCurrentPath('/home');
+
+        this.setAndFlush(controller, 'foo', null);
+        this.assertCurrentPath('/home', 'Setting property to null');
+
+        this.setAndFlush(controller, 'foo', emberA([1,3]));
+        this.assertCurrentPath('/home?foo=%5B1%2C3%5D');
+
+        this.setAndFlush(controller, 'foo', undefined);
+        this.assertCurrentPath('/home', 'Setting property to undefined');
+      });
+    });
+  }
+
+  ['@test {{link-to}} with null or undefined QPs does not get serialized into url'](assert) {
+    assert.expect(3);
+
+    this.addTemplate('home', '{{link-to \'Home\' \'home\' (query-params foo=nullValue) id=\'null-link\'}}{{link-to \'Home\' \'home\' (query-params foo=undefinedValue) id=\'undefined-link\'}}');
+
+    this.router.map(function() {
+      this.route('home');
+    });
+
+    this.setSingleQPController('home', 'foo', [], {
+      nullValue: null,
+      undefinedValue: undefined
+    });
+
+    return this.visitAndAssert('/home').then(() => {
+      assert.equal(this.$('#null-link').attr('href'), '/home');
+      assert.equal(this.$('#undefined-link').attr('href'), '/home');
+    });
+  }
+
   ['@test A child of a resource route still defaults to parent route\'s model even if the child route has a query param'](assert) {
     assert.expect(2);