Split mongodb connection creation from DatabaseController.

Author: nlutsenko

spec/DatabaseController.spec.js

@@ -1,15 +1,17 @@
-var DatabaseController = require('../src/Controllers/DatabaseController');
+'use strict';
+
+let DatabaseController = require('../src/Controllers/DatabaseController');
+let MongoStorageAdapter = require('../src/Adapters/Storage/Mongo/MongoStorageAdapter');
 
 describe('DatabaseController', () => {
-  it('can be constructed', (done) => {
-    var database = new DatabaseController('mongodb://localhost:27017/test',
-	{
+  it('can be constructed', done => {
+    let adapter = new MongoStorageAdapter('mongodb://localhost:27017/test');
+    let databaseController = new DatabaseController(adapter, {
 		collectionPrefix: 'test_'
-	});
-    database.connect().then(done, (error) => {
+    });
+    databaseController.connect().then(done, error => {
       console.log('error', error.stack);
       fail();
     });
   });
-
 });

src/Adapters/Storage/Mongo/MongoStorageAdapter.js

@@ -0,0 +1,29 @@
+
+let mongodb = require('mongodb');
+let MongoClient = mongodb.MongoClient;
+
+export class MongoStorageAdapter {
+  // Private
+  _uri: string;
+  // Public
+  connectionPromise;
+  database;
+
+  constructor(uri: string) {
+    this._uri = uri;
+  }
+
+  connect() {
+    if (this.connectionPromise) {
+      return this.connectionPromise;
+    }
+
+    this.connectionPromise = MongoClient.connect(this._uri).then(database => {
+      this.database = database;
+    });
+    return this.connectionPromise;
+  }
+}
+
+export default MongoStorageAdapter;
+module.exports = MongoStorageAdapter; // Required for tests

src/Controllers/DatabaseController.js

@@ -2,18 +2,17 @@
 // Parse database.
 
 var mongodb = require('mongodb');
-var MongoClient = mongodb.MongoClient;
 var Parse = require('parse/node').Parse;
 
 var Schema = require('./../Schema');
 var transform = require('./../transform');
 
 // options can contain:
 //   collectionPrefix: the string to put in front of every collection name.
-function DatabaseController(mongoURI, options = {}) {
-  this.mongoURI = mongoURI;
+function DatabaseController(adapter, { collectionPrefix } = {}) {
+  this.adapter = adapter;
 
-  this.collectionPrefix = options.collectionPrefix;
+  this.collectionPrefix = collectionPrefix;
 
   // We don't want a mutable this.schema, because then you could have
   // one request that uses different schemas for different parts of
@@ -28,17 +27,12 @@ function DatabaseController(mongoURI, options = {}) {
 // this.db will be populated with a Mongo "Db" object when the
 // promise resolves successfully.
 DatabaseController.prototype.connect = function() {
-  if (this.connectionPromise) {
-    // There's already a connection in progress.
-    return this.connectionPromise;
+  if (this.adapter.connectionPromise) {
+    return this.adapter.connectionPromise;
   }
-
-  this.connectionPromise = Promise.resolve().then(() => {
-    return MongoClient.connect(this.mongoURI);
-  }).then((db) => {
-    this.db = db;
+  return this.adapter.connect().then(() => {
+    this.db = this.adapter.database;
   });
-  return this.connectionPromise;
 };
 
 // Returns a promise for a Mongo collection.

src/DatabaseAdapter.js

@@ -13,9 +13,12 @@
 // * destroy(className, query, options)
 // * This list is incomplete and the database process is not fully modularized.
 //
-// Default is DatabaseController, which uses mongo at this time.
+// Default is MongoStorageAdapter.
 
-var adapter = require('./Controllers/DatabaseController');
+import DatabaseController from './Controllers/DatabaseController';
+import MongoStorageAdapter from './Adapters/Storage/Mongo/MongoStorageAdapter';
+
+let adapter = MongoStorageAdapter;
 var dbConnections = {};
 var databaseURI = 'mongodb://localhost:27017/parse';
 var appDatabaseURIs = {};
@@ -44,9 +47,12 @@ function getDatabaseConnection(appId: string, collectionPrefix: string) {
   }
 
   var dbURI = (appDatabaseURIs[appId] ? appDatabaseURIs[appId] : databaseURI);
-  dbConnections[appId] = new adapter(dbURI, {
+
+  let storageAdapter = new adapter(dbURI);
+  dbConnections[appId] = new DatabaseController(storageAdapter, {
     collectionPrefix: collectionPrefix
   });
+
   dbConnections[appId].connect();
   return dbConnections[appId];
 }