Merge pull request #1 from daumiller/OptionalDependencies

Merge PR58 from chaosfinity
scottwrobinson#58

lib/db.js

@@ -1,14 +1,35 @@
-var NeDbClient = require('./clients/nedbclient');
-var MongoClient = require('./clients/mongoclient');
+try {
+	var NeDbClient = require('./clients/nedbclient');
+} catch (e) {
+	if(e.code !== 'MODULE_NOT_FOUND') {
+		throw e;
+	}
+	var NeDbClient = null;
+}
+
+try {
+	var MongoClient = require('./clients/mongoclient');
+} catch (e) {
+	if(e.code !== 'MODULE_NOT_FOUND') {
+		throw e;
+	}
+	var MongoClient = null;
+}
 
 exports.connect = function(url, options) {
 	if (url.indexOf('nedb://') > -1) {
+		if(NeDbClient === null) {
+			return Promise.reject(new Error('The NeDB dependency has not been met'));
+		}
 		// url example: nedb://path/to/file/folder
 		return NeDbClient.connect(url, options).then(function(db) {
 			global.CLIENT = db;
 			return db;
 		});
 	} else if(url.indexOf('mongodb://') > -1) {
+		if(MongoClient === null) {
+			return Promise.reject(new Error('The MongoDB dependency has not been met'));
+		}
 		// url example: 'mongodb://localhost:27017/myproject'
 		return MongoClient.connect(url, options).then(function(db) {
 			global.CLIENT = db;
@@ -17,4 +38,4 @@ exports.connect = function(url, options) {
 	} else {
 		return Promise.reject(new Error('Unrecognized DB connection url.'));
 	}
-};
+};