Clean code.

src/js/repository/mongoClient.js

@@ -0,0 +1,52 @@
+const mongodb = require('mongodb');
+const assert = require('assert');
+
+const configuration = require('../configuration');
+const mongoConfig = configuration.database;
+
+class MongoClient {
+    constructor() {
+        mongodb.MongoClient.connect(mongoConfig.url, (error, client) => {
+            assert.equal(null, error, `Unable to connect to mongodb: ${error}.`);
+            console.log('Connected successfuly to mongodb');
+            this.db = client.db(mongoConfig.database);
+        });
+    }
+
+    find(collectionName, query, callback) {
+        this.db.collection(collectionName).find(query).toArray()
+            .then(results => {
+                console.log(`Entities ${collectionName} founded.`);
+                callback(results);
+            })
+            .catch(error => console.error(error));
+    }
+
+    insert(collectionName, entity, callback) {
+        this.db.collection(collectionName).insert(entity, (error, result) => {
+            assert.equal(null, error, `Unable to insert ${collectionName} entity: ${error}.`);
+            console.log(`Entity ${collectionName} inserted.`);
+            // Return only the inserted document.
+            callback(result.ops[0]);
+        });
+    }
+
+    update(collectionName, entity, callback) {
+        this.db.collection(collectionName).save(entity, (error) => {
+            assert.equal(null, error, `Unable to update ${collectionName} entity: ${error}.`);
+            console.log(`Entity ${collectionName} updated.`);
+            callback();
+        });
+    }
+
+    delete(collectionName, entityId, callback) {
+        this.db.collection(collectionName).deleteOne({_id: mongodb.ObjectId(entityId)}, (error, result) => {
+            assert.equal(null, error, `Unable to delete ${collectionName} entity with id ${entityId}: ${error}.`);
+            console.log(`Entity ${collectionName} with id ${entityId} deleted.`);
+            callback();
+        });
+    }
+}
+
+const mongoClient = new MongoClient();
+module.exports = mongoClient;