Create Mongo client factory

Author: rsaladocid

package-lock.json

@@ -25,6 +25,7 @@
     "@types/express": "^4.17.2",
     "@types/glob": "^7.1.1",
     "@types/helmet": "0.0.44",
+    "@types/mongodb": "^3.3.15",
     "@types/node": "~13.1.1",
     "@types/uuid": "^3.4.6",
     "@types/uuid-validate": "0.0.1",
@@ -39,6 +40,7 @@
     "helmet": "^3.21.2",
     "http-status": "^1.4.2",
     "mandrill-api": "^1.0.45",
+    "mongodb": "^3.5.2",
     "node-dependency-injection": "^2.4.2",
     "ts-node": "^8.3.0",
     "typescript": "^3.7.2",

package.json

@@ -0,0 +1,35 @@
+import { MongoClient } from 'mongodb';
+import config from '../../../../../apps/mooc_backend/config/config';
+import { Nullable } from '../../../domain/Nullable';
+
+export class MongoClientFactory {
+  private static clients: { [key: string]: MongoClient } = {};
+
+  static async createClient(contextName: string): Promise<MongoClient> {
+    let client = MongoClientFactory.getClient(contextName);
+
+    if (!client) {
+      client = await MongoClientFactory.createAndConnectClient();
+
+      MongoClientFactory.registerClient(client, contextName);
+    }
+
+    return client;
+  }
+
+  private static getClient(contextName: string): Nullable<MongoClient> {
+    return MongoClientFactory.clients[contextName];
+  }
+
+  private static async createAndConnectClient(): Promise<MongoClient> {
+    const client = new MongoClient(config.get('mongo.url'));
+
+    await client.connect();
+
+    return client;
+  }
+
+  private static registerClient(client: MongoClient, contextName: string): void {
+    MongoClientFactory.clients[contextName] = client;
+  }
+}

src/Contexts/Shared/infrastructure/persistence/mongo/MongoClientFactory.ts

@@ -6,6 +6,18 @@ const convictConfig = convict({
     format: ['production', 'development', 'staging', 'test'],
     default: 'default',
     env: 'NODE_ENV'
+  },
+  mongo: {
+    url: {
+      doc: 'The Mongo connection URL',
+      format: String,
+      env: 'MONGO_URL'
+    },
+    name: {
+      doc: 'The Mongo database name',
+      format: String,
+      env: 'MONGO_DB_NAME'
+    }
   }
 });
 

src/apps/mooc_backend/config/config.ts

@@ -0,0 +1,24 @@
+import { MongoClientFactory } from '../../../../src/Contexts/Shared/infrastructure/persistence/mongo/MongoClientFactory';
+import { MongoClient } from 'mongodb';
+
+describe('MongoClientFactory', () => {
+  const factory = MongoClientFactory;
+  let client: MongoClient;
+
+  beforeEach(async () => {
+    client = await factory.createClient('test');
+  });
+
+  afterEach(async () => {
+    await client.close();
+  });
+
+  it('creates a new client if it does not exist', () => {
+    expect(client).toBeInstanceOf(MongoClient);
+  });
+
+  it('creates a new client with existing name should return existing client', async () => {
+    const newClient = await factory.createClient('test');
+    expect(newClient).toBe(client);
+  });
+});