fix: handle changing discrim key on nested ops for GH issue Automatti…

…c#13906, PR Automattic#13938

lib/cast.js

@@ -71,7 +71,13 @@ module.exports = function cast(schema, obj, options, context) {
         if (val[k] == null || typeof val[k] !== 'object') {
           throw new CastError('Object', val[k], path + '.' + k);
         }
-        val[k] = cast(schema, val[k], options, context);
+        const discriminatorValue = val[k][schema.options.discriminatorKey];
+        if (discriminatorValue == null) {
+          val[k] = cast(schema, val[k], options, context);
+        } else {
+          const discriminatorSchema = getSchemaDiscriminatorByValue(context.schema, discriminatorValue);
+          val[k] = cast(discriminatorSchema ? discriminatorSchema : schema, val[k], options, context);
+        }
       }
     } else if (path === '$where') {
       type = typeof val;
@@ -278,7 +284,6 @@ module.exports = function cast(schema, obj, options, context) {
         } else {
           const ks = Object.keys(val);
           let $cond;
-
           let k = ks.length;
 
           while (k--) {
@@ -361,4 +366,4 @@ function _cast(val, numbertype, context) {
       }
     }
   }
-}
+}

lib/query.js

@@ -4746,7 +4746,6 @@ function _getPopulatedPaths(list, arr, prefix) {
 
 Query.prototype.cast = function(model, obj) {
   obj || (obj = this._conditions);
-
   model = model || this.model;
 
   const discriminatorKey = model.schema.options.discriminatorKey;

lib/schematype.js

@@ -1070,7 +1070,6 @@ SchemaType.prototype.applySetters = function(value, scope, init, priorVal, optio
   if (v == null) {
     return this._castNullish(v);
   }
-
   // do not cast until all setters are applied #665
   v = this.cast(v, scope, init, priorVal, options);
 

test/model.discriminator.test.js

@@ -1645,4 +1645,35 @@ describe('model', function() {
     actions.discriminator('message', Message.schema);
     assert.ok(actions.schema.discriminators['message']);
   });
+
+  it('should not fail when using a discriminator key multiple times (gh-13906)', async function() {
+    const options = { discriminatorKey: 'type' };
+    const eventSchema = new Schema({ date: Schema.Types.Date }, options);
+    const Event = db.model('gh-13906-event', eventSchema);
+
+
+    const clickedLinkEventSchema = new Schema({ url: String }, options);
+    const ClickedLinkEvent = Event.discriminator('ClickedLinkEvent', clickedLinkEventSchema, 'clickedLinkEvent');
+
+
+    const clickedImageEventSchema = new Schema({ image: String }, options);
+    const ClickedImageEvent = Event.discriminator('ClickedImageEvent', clickedImageEventSchema, 'clickedImageEvent');
+
+    const clickedLinkEvent = new ClickedLinkEvent({ url: 'https://clicked-link.com' });
+    assert.equal(clickedLinkEvent.type, 'clickedLinkEvent');
+    assert.equal(clickedLinkEvent.url, 'https://clicked-link.com');
+
+    const clickedImageEvent = new ClickedImageEvent({ image: 'clicked-image.png' });
+    assert.equal(clickedImageEvent.type, 'clickedImageEvent');
+    assert.equal(clickedImageEvent.image, 'clicked-image.png');
+    const query = {
+        type: 'clickedLinkEvent',
+        $or: [
+            { type: 'clickedImageEvent' }
+        ]
+    };
+    const result = await Event.find(query).exec();
+    assert(result);
+
+  });
 });