fix(populate): handle virtual populate of an embedded discriminator nested path

Fix #8173
Re: #6488

Author: vkarpov15

lib/helpers/populate/getModelsMapForPopulate.js

@@ -78,12 +78,14 @@ module.exports = function getModelsMapForPopulate(model, docs, options) {
       }
     }
 
-    const virtual = getVirtual(model.schema, options.path);
+    const _virtualRes = getVirtual(model.schema, options.path);
+    const virtual = _virtualRes == null ? null : _virtualRes.virtual;
+
     let localField;
     let count = false;
     if (virtual && virtual.options) {
-      const virtualPrefix = virtual.$nestedSchemaPath ?
-        virtual.$nestedSchemaPath + '.' : '';
+      const virtualPrefix = _virtualRes.nestedSchemaPath ?
+        _virtualRes.nestedSchemaPath + '.' : '';
       if (typeof virtual.options.localField === 'function') {
         localField = virtualPrefix + virtual.options.localField.call(doc, doc);
       } else {
@@ -312,7 +314,8 @@ module.exports = function getModelsMapForPopulate(model, docs, options) {
       } else {
         schemaForCurrentDoc = schema;
       }
-      const virtual = getVirtual(modelForCurrentDoc.schema, options.path);
+      const _virtualRes = getVirtual(modelForCurrentDoc.schema, options.path);
+      const virtual = _virtualRes == null ? null : _virtualRes.virtual;
 
       let ref;
       let refPath;

lib/helpers/populate/getVirtual.js

@@ -8,7 +8,7 @@ module.exports = getVirtual;
 
 function getVirtual(schema, name) {
   if (schema.virtuals[name]) {
-    return schema.virtuals[name];
+    return { virtual: schema.virtuals[name], path: void 0 };
   }
   const parts = name.split('.');
   let cur = '';
@@ -17,8 +17,7 @@ function getVirtual(schema, name) {
     cur += (cur.length > 0 ? '.' : '') + parts[i];
     if (schema.virtuals[cur]) {
       if (i === parts.length - 1) {
-        schema.virtuals[cur].$nestedSchemaPath = nestedSchemaPath;
-        return schema.virtuals[cur];
+        return { virtual: schema.virtuals[cur], path: nestedSchemaPath };
       }
       continue;
     }
@@ -33,20 +32,24 @@ function getVirtual(schema, name) {
 
       if (schema.virtuals[rest]) {
         if (i === parts.length - 2) {
-          schema.virtuals[rest].$nestedSchemaPath =
-            [nestedSchemaPath, cur].filter(v => !!v).join('.');
-          return schema.virtuals[rest];
+          return {
+            virtual: schema.virtuals[rest],
+            nestedSchemaPath:[nestedSchemaPath, cur].filter(v => !!v).join('.')
+          };
         }
         continue;
       }
 
       if (i + 1 < parts.length && schema.discriminators) {
         for (const key of Object.keys(schema.discriminators)) {
-          const _virtual = getVirtual(schema.discriminators[key], rest);
-          if (_virtual != null) {
-            _virtual.$nestedSchemaPath = [nestedSchemaPath, cur].
+          const res = getVirtual(schema.discriminators[key], rest);
+          if (res != null) {
+            const _path = [nestedSchemaPath, cur, res.nestedSchemaPath].
               filter(v => !!v).join('.');
-            return _virtual;
+            return {
+              virtual: res.virtual,
+              nestedSchemaPath: _path
+            };
           }
         }
       }

test/helpers/populate.getVirtual.test.js

@@ -39,7 +39,7 @@ describe('getVirtual', function() {
       product: { type: String }
     }));
 
-    assert.equal(getVirtual(batchSchema, 'nested.events.users_$').options.ref,
+    assert.equal(getVirtual(batchSchema, 'nested.events.users_$').virtual.options.ref,
       'Users');
 
     done();
@@ -80,8 +80,8 @@ describe('getVirtual', function() {
     // Second embedded discriminator
     docArray.discriminator('Purchased', new Schema({ product: String }));
 
-    const virtual = getVirtual(batchSchema, 'nested.events.nestedLayer.users_$');
-    assert.equal(virtual.options.ref, 'Users');
+    const res = getVirtual(batchSchema, 'nested.events.nestedLayer.users_$');
+    assert.equal(res.virtual.options.ref, 'Users');
 
     done();
   });
@@ -106,13 +106,13 @@ describe('getVirtual', function() {
 
     docArray.discriminator('Clicked', clickedSchema);
 
-    let virtual = getVirtual(batchSchema, 'events.users_$');
-    assert.equal(virtual.options.ref, 'Users');
-    assert.equal(virtual.$nestedSchemaPath, 'events');
+    let res = getVirtual(batchSchema, 'events.users_$');
+    assert.equal(res.virtual.options.ref, 'Users');
+    assert.equal(res.nestedSchemaPath, 'events');
 
-    virtual = getVirtual(batchSchema, 'events.users_$');
-    assert.equal(virtual.options.ref, 'Users');
-    assert.equal(virtual.$nestedSchemaPath, 'events');
+    res = getVirtual(batchSchema, 'events.users_$');
+    assert.equal(res.virtual.options.ref, 'Users');
+    assert.equal(res.nestedSchemaPath, 'events');
 
     done();
   });

test/model.populate.test.js

@@ -8628,7 +8628,7 @@ describe('model: populate:', function() {
     });
   });
 
-  it('handles virtual populate underneath embedded discriminator nested path (gh-6488) (gh-8173)', function() {
+  it('handles virtual populate of an embedded discriminator nested path (gh-6488) (gh-8173)', function() {
     return co(function*() {
       const UserModel = db.model('gh6488_User', Schema({
         employeeId: Number,
@@ -8646,10 +8646,8 @@ describe('model: populate:', function() {
       });
 
       const docArray = batchSchema.path('nested.events');
-      const Clicked = docArray.
-        discriminator('gh6488_Clicked', Schema({ nestedLayer: nestedLayerSchema }));
-      const Purchased = docArray.
-        discriminator('gh6488_Purchased', Schema({ purchased: String }));
+      docArray.discriminator('gh6488_Clicked', Schema({ nestedLayer: nestedLayerSchema }));
+      docArray.discriminator('gh6488_Purchased', Schema({ purchased: String }));
 
       const Batch = db.model('gh6488', batchSchema);