Express-Lemon: Back-End Boilerplate

1. Description

• Ideology
• Middleware Entities
• Services
• Commands

2. Installation

• Requirements
• Installation Steps
• Running the package

Description

Initial API Architecture. Contains a basic and must-have set of modules, services and configurations.

Ideology

Use Express Middlewares in order to split functionality and have logically separated parts. Each router/endpoint may have a chain of middlewares to validate data, load data from data sources, map data, check permissions and perform the main business logic.

Each Middleware function should have the same name through the whole chain set.

Example: If a new request of user creation process passes multiple middleware functions, all of them should have the same name (createOne(req, res, next))

*Exception: unrelated 'helper' middlewares

Example:

appRoute.get('/:userId',
  authMiddleware.isAuthenticated,
  acl.getOne,
  validator.getOne,
  loader.getOne,
  controller.getOne,
);

Middleware Entities

./app/middlewares/

Chain items to perform own specific functionality.

Access Control (accessControl)

Checks if the current request may reach a business logic. This layer may check if a logged in user has permissions to perform this request.

Example:

async getOne(req, res, next) {
    if (mainAcl.isAdmin(req.user)) {
      return next();
    }

    const userIdRequested   = req.params.userId;
    const userIdCurrent     = req.user._id.toString();

    if (userIdRequested === userIdCurrent) {
      return next();
    }

    return next(new Forbidden());
},

Data Mappers (dataMappers)

Maps Outgoing/Incoming data for further processing by another function.

Example:

updateOne(req, res, next) {
    delete req.body.password;
    delete req.body.confirm_password;
    return next();
},

Data Validators (dataValidators)

Validates incoming data according to installed rules to prevent invalid data from handling.

Example:

deleteOne(req, res, next) {
    req.assert('userId', 'Valid user id should be provided').notEmpty().isMongoId();
    mainValidator.handleValidationResult(mainValidator.validateErrorsSync(req), res, next);
},

Entity Loaders (entityLoaders)

Loads/Gets required by business logic entities/objects from available data sources. The system may retrieve users or related entities from a database or process a data.

Stores and passes loaded entities in a special object inside the req (request) object. The Entity Loader Service should be used to sed all of the entities and pass within the request object.

Example:

async getOne(req, res, next) {
    try {
      const userFound = await UserService.findOne({ query: { _id: req.params.userId }, options: { lean: true } });
      if (!mainHelper.isObjectValid(userFound)) {
        throw new NotFound('user not found');
      }

      MainLoader.setEntities(req, { user: userFound });
      return next();

    } catch (err) {
      return next(err);
    }
},

Services

./app/services/

Services perform single-minded focus functionality to be invoked inside the application for handling business logic.

• Authentication Service (access/refresh token flow)
• Crypto Service
• Database Service
• Email Service
• Entity Loader Service
• Log Service
• Response Service
• User Service

Commands

./commands

• Admin User creation script

Installation

Requirements

Node

Visit https://nodejs.org for installation details.

npm

Node Package Manager, should come bundled with node.

MongoDB

Install MongoDB https://docs.mongodb.com/manual/installation/

Installation Steps

Clone the package

1. Create a folder with the chosen name
2. Run $ git clone <package url> .

install dependencies

1. Go to the package root folder
2. Run $ npm install

App Settings

1. Create config/env/env.local file and copy data from config/env/env.local_example
2. Update settings according to your needs and environment specifications

Test Environment Settings

1. Create config/env/.env.test file and copy data from config/env/.env.test_example
2. Update settings according to your needs and environment specifications

Running the package

$ npm run start:[environment]

Example: $ npm run start:local