fix(mongodb): prevent "db.collections is not a function" error (#232)

What does this PR do / solve?
-----------------------------

Initial goal was to fix the following warning: `DeprecationWarning: current Server Discovery and Monitoring engine is deprecated, and will be removed in a future version. To use the new Server Discover and Monitoring engine, pass option { useUnifiedTopology: true } to MongoClient.connect`

As a first step, this PR fixes the `db.collections is not a function` error, when trying to run `docker-compose up --build`.

Overview of changes
-------------------

- upgrade the `mongodb` client to a more recent version: `2.2.33`
- switch to the new Mongo URI format

How to test this PR?
--------------------

```
$ docker-compose up --build -d
$ npm run test-docker
```

app/models/mongodb.js

@@ -144,12 +144,14 @@ exports.init = function(readyCallback) {
   var authStr = '';
   if (authUser && authPassword) authStr = authUser + ':' + authPassword + '@';
 
-  var url = 'mongodb://' + authStr + host + ':' + port + '/' + dbName; // + "?w=1";
+  var url = 'mongodb://' + authStr + host + ':' + port; // + "?w=1";
 
-  console.log('Connecting to ' + url + '...');
+  console.log('Connecting to ' + url + '/' + dbName + '...');
 
   var options = {
     native_parser: true,
+    useNewUrlParser: true,
+    useUnifiedTopology: true,
     //strict: false,
     //safe: false,
     w: 'majority' // write concern: (value of > -1 or the string 'majority'), where < 1 means no write acknowlegement
@@ -158,9 +160,11 @@ exports.init = function(readyCallback) {
   //var dbserver = new mongodb.Server(host, port, {auto_reconnect:true});
   //var db = new mongodb.Db(dbName, dbserver, options);
 
-  mongodb.MongoClient.connect(url, options, function(err, db) {
+  mongodb.MongoClient.connect(url, options, function(err, client) {
     if (err) throw err;
 
+    const db = client.db(dbName);
+
     db.addListener('error', function(e) {
       console.log('MongoDB model async error: ', e);
     });

package.json

@@ -61,7 +61,7 @@
     "hogan.js": "2.0.0",
     "htmlparser": "*",
     "iconv": ">=2.0.6",
-    "mongodb": "^2.2.29",
+    "mongodb": "^2.2.33",
     "object-sizeof": "^1.3.0",
     "playemjs": "0.3.0",
     "q-set": "^2.0.8",

scripts/algolia-search-index/mongodb-wrapper.js

@@ -3,20 +3,21 @@ const Progress = require('./Progress');
 
 var MONGO_OPTIONS = {
   native_parser: true,
+  useNewUrlParser: true,
+  useUnifiedTopology: true,
   //strict: false,
   //safe: false,
   w: 'majority' // write concern: (value of > -1 or the string 'majority'), where < 1 means no write acknowlegement
 };
 
 const makeConnUrl = params => {
-  var dbName = params.mongoDbDatabase || process.env.MONGODB_DATABASE;
   var host = params.mongoDbHost || process.env.MONGODB_HOST;
   var port = params.mongoDbPort || process.env.MONGODB_PORT;
   var authUser = params.mongoDbAuthUser || process.env.MONGODB_USER;
   var authPassword = params.mongoDbAuthPassword || process.env.MONGODB_PASS;
   var authStr =
     authUser && authPassword ? authUser + ':' + authPassword + '@' : '';
-  return 'mongodb://' + authStr + host + ':' + port + '/' + dbName;
+  return 'mongodb://' + authStr + host + ':' + port;
 };
 
 // populates db.<collection_name>, for each collection
@@ -41,14 +42,15 @@ const cacheCollections = function(db, callback) {
 
 const initMongo = (params, callback) => {
   var url = makeConnUrl(params);
-  console.log('Connecting to ' + url + '...');
-  mongodb.MongoClient.connect(url, MONGO_OPTIONS, (err, db) => {
+  var dbName = params.mongoDbDatabase || process.env.MONGODB_DATABASE;
+  console.log('Connecting to ' + url + '/' + dbName + '...');
+  mongodb.MongoClient.connect(url, MONGO_OPTIONS, (err, client) => {
     if (err) {
       callback(err);
     } else {
+      const db = client.db(dbName);
       db.addListener('error', function(err) {
         console.log('MongoDB model async error: ', err);
-        throw err;
       });
       cacheCollections(db, callback); // will mutate db and callback
     }