Aggregate allow multiple of same stage

spec/ParseQuery.Aggregate.spec.js

@@ -744,4 +744,47 @@ describe('Parse.Query Aggregate testing', () => {
       fail(err);
     });
   });
+
+  it_exclude_dbs(['postgres'])('aggregate allow multiple of same stage', (done) => {
+    const pointer1 = new TestObject({ value: 1});
+    const pointer2 = new TestObject({ value: 2});
+    const pointer3 = new TestObject({ value: 3});
+
+    const obj1 = new TestObject({ pointer: pointer1, name: 'Hello' });
+    const obj2 = new TestObject({ pointer: pointer2, name: 'Hello' });
+    const obj3 = new TestObject({ pointer: pointer3, name: 'World' });
+
+    const options = Object.assign({}, masterKeyOptions, {
+      body: [{
+        match: { name: "Hello" },
+      }, {
+        // Transform className$objectId to objectId and store in new field tempPointer
+        project: {
+          tempPointer: { $substr: [ "$_p_pointer", 11, -1 ] }, // Remove TestObject$
+        },
+      }, {
+        // Left Join, replace objectId stored in tempPointer with an actual object
+        lookup: {
+          from: "test_TestObject",
+          localField: "tempPointer",
+          foreignField: "_id",
+          as: "tempPointer"
+        },
+      }, {
+        // lookup returns an array, Deconstructs an array field to objects
+        unwind: {
+          path: "$tempPointer",
+        },
+      }, {
+        match : { "tempPointer.value" : 2 },
+      }]
+    });
+    Parse.Object.saveAll([pointer1, pointer2, pointer3, obj1, obj2, obj3]).then(() => {
+      return rp.get(Parse.serverURL + '/aggregate/TestObject', options);
+    }).then((resp) => {
+      expect(resp.results.length).toEqual(1);
+      expect(resp.results[0].tempPointer.value).toEqual(2);
+      done();
+    });
+  });
 });

src/Routers/AggregateRouter.js

@@ -4,60 +4,56 @@ import * as middleware from '../middlewares';
 import Parse         from 'parse/node';
 import UsersRouter   from './UsersRouter';
 
-const ALLOWED_KEYS = [
-  'where',
-  'distinct',
-  'project',
+const BASE_KEYS = ['where', 'distinct'];
+
+const PIPELINE_KEYS = [
+  'addFields',
+  'bucket',
+  'bucketAuto',
+  'collStats',
+  'count',
+  'currentOp',
+  'facet',
+  'geoNear',
+  'graphLookup',
+  'group',
+  'indexStats',
+  'limit',
+  'listLocalSessions',
+  'listSessions',
+  'lookup',
   'match',
+  'out',
+  'project',
   'redact',
-  'limit',
-  'skip',
-  'unwind',
-  'group',
+  'replaceRoot',
   'sample',
+  'skip',
   'sort',
-  'geoNear',
-  'lookup',
-  'out',
-  'indexStats',
-  'facet',
-  'bucket',
-  'bucketAuto',
   'sortByCount',
-  'addFields',
-  'replaceRoot',
-  'count',
-  'graphLookup',
+  'unwind',
 ];
 
+const ALLOWED_KEYS = [...BASE_KEYS, ...PIPELINE_KEYS];
+
 export class AggregateRouter extends ClassesRouter {
 
   handleFind(req) {
     const body = Object.assign(req.body, ClassesRouter.JSONFromQuery(req.query));
     const options = {};
-    const pipeline = [];
+    let pipeline = [];
 
-    for (const key in body) {
-      if (ALLOWED_KEYS.indexOf(key) === -1) {
-        throw new Parse.Error(Parse.Error.INVALID_QUERY, `Invalid parameter for query: ${key}`);
+    if (Array.isArray(body)) {
+      pipeline = body.map((stage) => {
+        const stageName = Object.keys(stage)[0];
+        return this.transformStage(stageName, stage);
+      });
+    } else {
+      const stages = [];
+      for (const stageName in body) {
+        stages.push(this.transformStage(stageName, body));
       }
-      if (key === 'group') {
-        if (body[key].hasOwnProperty('_id')) {
-          throw new Parse.Error(
-            Parse.Error.INVALID_QUERY,
-            `Invalid parameter for query: group. Please use objectId instead of _id`
-          );
-        }
-        if (!body[key].hasOwnProperty('objectId')) {
-          throw new Parse.Error(
-            Parse.Error.INVALID_QUERY,
-            `Invalid parameter for query: group. objectId is required`
-          );
-        }
-        body[key]._id = body[key].objectId;
-        delete body[key].objectId;
-      }
-      pipeline.push({ [`$${key}`]: body[key] });
+      pipeline = stages;
     }
     if (body.distinct) {
       options.distinct = String(body.distinct);
@@ -76,6 +72,32 @@ export class AggregateRouter extends ClassesRouter {
     });
   }
 
+  transformStage(stageName, stage) {
+    if (ALLOWED_KEYS.indexOf(stageName) === -1) {
+      throw new Parse.Error(
+        Parse.Error.INVALID_QUERY,
+        `Invalid parameter for query: ${stageName}`
+      );
+    }
+    if (stageName === 'group') {
+      if (stage[stageName].hasOwnProperty('_id')) {
+        throw new Parse.Error(
+          Parse.Error.INVALID_QUERY,
+          `Invalid parameter for query: group. Please use objectId instead of _id`
+        );
+      }
+      if (!stage[stageName].hasOwnProperty('objectId')) {
+        throw new Parse.Error(
+          Parse.Error.INVALID_QUERY,
+          `Invalid parameter for query: group. objectId is required`
+        );
+      }
+      stage[stageName]._id = stage[stageName].objectId;
+      delete stage[stageName].objectId;
+    }
+    return { [`$${stageName}`]: stage[stageName] };
+  }
+
   mountRoutes() {
     this.route('GET','/aggregate/:className', middleware.promiseEnforceMasterKeyAccess, req => { return this.handleFind(req); });
   }