Support for Aggregate Queries

src/Adapters/Storage/Mongo/MongoCollection.js

@@ -60,6 +60,14 @@ export default class MongoCollection {
     return countOperation;
   }
 
+  distinct(field, query) {
+    return this._mongoCollection.distinct(field, query);
+  }
+
+  aggregate(pipeline, { maxTimeMS, readPreference } = {}) {
+    return this._mongoCollection.aggregate(pipeline, { maxTimeMS, readPreference }).toArray();
+  }
+
   insertOne(object) {
     return this._mongoCollection.insertOne(object);
   }

src/Adapters/Storage/Mongo/MongoStorageAdapter.js

@@ -405,6 +405,27 @@ export class MongoStorageAdapter {
       }));
   }
 
+  distinct(className, schema, query, fieldName) {
+    schema = convertParseSchemaToMongoSchema(schema);
+    return this._adaptiveCollection(className)
+      .then(collection => collection.distinct(fieldName, transformWhere(className, query, schema)));
+  }
+
+  aggregate(className, pipeline, readPreference) {
+    readPreference = this._parseReadPreference(readPreference);
+    return this._adaptiveCollection(className)
+      .then(collection => collection.aggregate(pipeline, { readPreference, maxTimeMS: this._maxTimeMS }))
+      .then(results => {
+        results.forEach(result => {
+          if (result.hasOwnProperty('_id')) {
+            result.objectId = result._id;
+            delete result._id;
+          }
+        });
+        return results;
+      });
+  }
+
   _parseReadPreference(readPreference) {
     if (readPreference) {
       switch (readPreference) {

src/Adapters/Storage/Postgres/PostgresStorageAdapter.js

@@ -165,6 +165,10 @@ const transformDotField = (fieldName) => {
   return name;
 }
 
+const transformAggregateField = (fieldName) => {
+  return fieldName.substr(1);
+}
+
 const validateKeys = (object) => {
   if (typeof object == 'object') {
     for (const key in object) {
@@ -1366,6 +1370,140 @@ export class PostgresStorageAdapter {
     });
   }
 
+  distinct(className, schema, query, fieldName) {
+    debug('distinct', className, query);
+    let field = fieldName;
+    let column = fieldName;
+    if (fieldName.indexOf('.') >= 0) {
+      field = transformDotFieldToComponents(fieldName).join('->');
+      column = fieldName.split('.')[0];
+    }
+    const isArrayField = schema.fields
+          && schema.fields[fieldName]
+          && schema.fields[fieldName].type === 'Array';
+    const values = [field, column, className];
+    const where = buildWhereClause({ schema, query, index: 4 });
+    values.push(...where.values);
+
+    const wherePattern = where.pattern.length > 0 ? `WHERE ${where.pattern}` : '';
+    let qs = `SELECT DISTINCT ON ($1:raw) $2:raw FROM $3:name ${wherePattern}`;
+    if (isArrayField) {
+      qs = `SELECT distinct jsonb_array_elements($1:raw) as $2:raw FROM $3:name ${wherePattern}`;
+    }
+    debug(qs, values);
+    return this._client.any(qs, values)
+      .catch(() => [])
+      .then((results) => {
+        if (fieldName.indexOf('.') === -1) {
+          return results.map(object => object[field]);
+        }
+        const child = fieldName.split('.')[1];
+        return results.map(object => object[column][child]);
+      });
+  }
+
+  aggregate(className, pipeline) {
+    debug('aggregate', className, pipeline);
+    const values = [className];
+    let columns = [];
+    let countField = null;
+    let wherePattern = '';
+    let limitPattern = '';
+    let skipPattern = '';
+    let sortPattern = '';
+    let groupPattern = '';
+    for (let i = 0; i < pipeline.length; i += 1) {
+      const stage = pipeline[i];
+      if (stage.$group) {
+        for (const field in stage.$group) {
+          const value = stage.$group[field];
+          if (value === null || value === undefined) {
+            continue;
+          }
+          if (field === '_id') {
+            columns.push(`${transformAggregateField(value)} AS "objectId"`);
+            groupPattern = `GROUP BY ${transformAggregateField(value)}`;
+            continue;
+          }
+          if (value.$sum) {
+            if (typeof value.$sum === 'string') {
+              columns.push(`SUM(${transformAggregateField(value.$sum)}) AS "${field}"`);
+            } else {
+              countField = field;
+              columns.push(`COUNT(*) AS "${field}"`);
+            }
+          }
+          if (value.$max) {
+            columns.push(`MAX(${transformAggregateField(value.$max)}) AS "${field}"`);
+          }
+          if (value.$min) {
+            columns.push(`MIN(${transformAggregateField(value.$min)}) AS "${field}"`);
+          }
+          if (value.$avg) {
+            columns.push(`AVG(${transformAggregateField(value.$avg)}) AS "${field}"`);
+          }
+        }
+        columns.join(',');
+      } else {
+        columns.push('*');
+      }
+      if (stage.$project) {
+        if (columns.includes('*')) {
+          columns = [];
+        }
+        for (const field in stage.$project) {
+          const value = stage.$project[field];
+          if ((value === 1 || value === true)) {
+            columns.push(field);
+          }
+        }
+      }
+      if (stage.$match) {
+        const patterns = [];
+        for (const field in stage.$match) {
+          const value = stage.$match[field];
+          Object.keys(ParseToPosgresComparator).forEach(cmp => {
+            if (value[cmp]) {
+              const pgComparator = ParseToPosgresComparator[cmp];
+              patterns.push(`${field} ${pgComparator} ${value[cmp]}`);
+            }
+          });
+        }
+        wherePattern = patterns.length > 0 ? `WHERE ${patterns.join(' ')}` : '';
+      }
+      if (stage.$limit) {
+        limitPattern = `LIMIT ${stage.$limit}`;
+      }
+      if (stage.$skip) {
+        skipPattern = `OFFSET ${stage.$skip}`;
+      }
+      if (stage.$sort) {
+        const sort = stage.$sort;
+        const sorting = Object.keys(sort).map((key) => {
+          if (sort[key] === 1) {
+            return `"${key}" ASC`;
+          }
+          return `"${key}" DESC`;
+        }).join(',');
+        sortPattern = sort !== undefined && Object.keys(sort).length > 0 ? `ORDER BY ${sorting}` : '';
+      }
+    }
+
+    const qs = `SELECT ${columns} FROM $1:name ${wherePattern} ${sortPattern} ${limitPattern} ${skipPattern} ${groupPattern}`;
+    debug(qs, values);
+    return this._client.any(qs, values).then(results => {
+      if (countField) {
+        results[0][countField] = parseInt(results[0][countField], 10);
+      }
+      results.forEach(result => {
+        if (!result.hasOwnProperty('objectId')) {
+          result.objectId = null;
+        }
+      });
+      return results;
+    });
+  }
+
   performInitialization({ VolatileClassesSchemas }) {
     debug('performInitialization');
     const promises = VolatileClassesSchemas.map((schema) => {

src/Controllers/DatabaseController.js

@@ -785,6 +785,8 @@ DatabaseController.prototype.find = function(className, query, {
   count,
   keys,
   op,
+  distinct,
+  pipeline,
   readPreference
 } = {}) {
   const isMaster = acl === undefined;
@@ -853,6 +855,18 @@ DatabaseController.prototype.find = function(className, query, {
                 } else {
                   return this.adapter.count(className, schema, query, readPreference);
                 }
+              }  else if (distinct) {
+                if (!classExists) {
+                  return [];
+                } else {
+                  return this.adapter.distinct(className, schema, query, distinct);
+                }
+              }  else if (pipeline) {
+                if (!classExists) {
+                  return [];
+                } else {
+                  return this.adapter.aggregate(className, pipeline, readPreference);
+                }
               } else {
                 if (!classExists) {
                   return [];

src/ParseServer.js

@@ -34,6 +34,7 @@ import { SessionsRouter }       from './Routers/SessionsRouter';
 import { UsersRouter }          from './Routers/UsersRouter';
 import { PurgeRouter }          from './Routers/PurgeRouter';
 import { AudiencesRouter }      from './Routers/AudiencesRouter';
+import { AggregateRouter }      from './Routers/AggregateRouter';
 
 import { ParseServerRESTController } from './ParseServerRESTController';
 import * as controllers from './Controllers';
@@ -197,7 +198,8 @@ class ParseServer {
       new PurgeRouter(),
       new HooksRouter(),
       new CloudCodeRouter(),
-      new AudiencesRouter()
+      new AudiencesRouter(),
+      new AggregateRouter()
     ];
 
     const routes = routers.reduce((memo, router) => {

src/RestQuery.js

@@ -86,6 +86,8 @@ function RestQuery(config, auth, className, restWhere = {}, restOptions = {}, cl
     case 'count':
       this.doCount = true;
       break;
+    case 'distinct':
+    case 'pipeline':
     case 'skip':
     case 'limit':
     case 'readPreference':

src/Routers/AggregateRouter.js

@@ -0,0 +1,77 @@
+import ClassesRouter from './ClassesRouter';
+import rest from '../rest';
+import * as middleware from '../middlewares';
+import Parse         from 'parse/node';
+
+const ALLOWED_KEYS = [
+  'where',
+  'distinct',
+  'project',
+  'match',
+  'redact',
+  'limit',
+  'skip',
+  'unwind',
+  'group',
+  'sample',
+  'sort',
+  'geoNear',
+  'lookup',
+  'out',
+  'indexStats',
+  'facet',
+  'bucket',
+  'bucketAuto',
+  'sortByCount',
+  'addFields',
+  'replaceRoot',
+  'count',
+  'graphLookup',
+];
+
+export class AggregateRouter extends ClassesRouter {
+
+  handleFind(req) {
+    const body = Object.assign(req.body, ClassesRouter.JSONFromQuery(req.query));
+    const options = {};
+    const 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 (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] });
+    }
+    if (body.distinct) {
+      options.distinct = String(body.distinct);
+    }
+    options.pipeline = pipeline;
+    if (typeof body.where === 'string') {
+      body.where = JSON.parse(body.where);
+    }
+    return rest.find(req.config, req.auth, this.className(req), body.where, options, req.info.clientSDK)
+      .then((response) => { return { response }; });
+  }
+
+  mountRoutes() {
+    this.route('GET','/aggregate/:className', middleware.promiseEnforceMasterKeyAccess, req => { return this.handleFind(req); });
+  }
+}
+
+export default AggregateRouter;