exprest4

Yet another RESTful API framework for Express 4.x.

Install

$ npm install exprest4

Note that you have to npm install express as well because exprest4 doesn't install Express 4.x by itself.

Getting started

Controllers

Make controllers directory and code your Express application.

$ mkdir controllers
$ vim app.js

// app.js
 
'use strict';
 
const express = require('express')
    , exprest = require('exprest4')
    , app = express()
;
 
exprest.route(app, { url: '/api' })
.then(() => {
  app.listen();
});

exprest4 regards each file/directory under the controllers directory as a controller module in terms of MVC, and routes everything upon route() call. Each controller module must have the special property __exprest as follow:

// controllers/example.js
 
'use strict';
 
module.exports = {
  __exprest: {
    routes: [{
      action: 'list'
    }, {
      action: 'view'
    , path: ':id'
    }, {
      action: 'create'
    , method: 'post'
    }, {
      action: 'update'
    , path: ':id'
    , method: 'put'
    }, {
      action: 'remove'
    , path: ':id'
    , method: 'delete'
    }]
  }
 
, list: (req, res) => {
    res.json({ action: 'list' });
  }
 
, view: (req, res) => {
    res.json({ action: 'view', id: req.params.id });
  }
 
, create: (req, res) => {
    res.json({ action: 'create' });
  }
 
, update: (req, res) => {
    res.json({ action: 'update', id: req.params.id });
  }
 
, remove: (req, res) => {
    res.json({ action: 'remove', id: req.params.id });
  }
};

The code implemented in controllers/example.js is equivalent to the following Express calls:

'use strict';
 
const example = require('./controllers/example');
 
app.get('/api/example', example.list);
app.get('/api/example/:id', example.view);
app.post('/api/example', example.create);
app.put('/api/example/:id', example.update);
app.delete('/api/example/:id', example.remove);

Models

If your application works with a database, exprest4 also allows you to define models by using Sequelize. Make models directory and add to call model() as follows:

$ mkdir models
$ vim app.js

exprest4 regards each file/directory under the models directory as a model module in manner of Sequelize, and loads all models into a Sequelize instance upon model() call.

// models/project.js
 
'use strict';
 
module.exports = (sequelize, DataTypes) => {
  return sequelize.define('project', {
    title: DataTypes.STRING
  , description: DataTypes.TEXT
  });
};
 
 
// app.js
 
'use strict';
 
const express = require('express')
    , exprest = require('exprest4')
    , app = express()
;
 
exprest.route(app, { url: '/api' })
.then(() => exprest.model({ dialect: 'sqlite' })) // Use SQLite with memory storage
.then((sequelize) => {
  app.locals.models = sequelize.models; // Save the models for controllers
  return sequelize.sync();
})
.then(() => {
  app.listen();
});

model() returns Promise with a Sequelize instance.

It's a good idea to save the models as app.locals.models as above code in app.js, so that each controller can access to the models through req.app.locals.models as the following code:

// controllers/project.js
 
'use strict';
 
function project(req)
{
  return req.app.locals.models.project;
}
 
module.exports = {
  __exprest: {
    routes: [{
      action: 'list'
    }, {
      action: 'view'
    , path: ':id'
    }, {
      action: 'create'
    , method: 'post'
    }, {
      action: 'update'
    , path: ':id'
    , method: 'put'
    }, {
      action: 'remove'
    , path: ':id'
    , method: 'delete'
    }]
  }
 
, list: (req, res, next) => {
    project(req).findAll()
    .then((rows) => { res.json(rows); })
    .catch(next);
  }
 
, view: (req, res, next) => {
    project(req).findById(req.params.id)
    .then((row) => { row ? res.json(row) : res.status(404); })
    .catch(next);
  }
 
, create: (req, res, next) => {
    project(req).create({
      title: req.body.title
    , description: req.body.description
    })
    .then((row) => { res.json(row); })
    .catch(next);
  }
 
, update: (req, res, next) => {
    project(req).findById(req.params.id)
    .then((row) => {
      if (!row) {
        res.status(404);
        return Promise.resolve();
      }
      return row.update({
        title: req.body.title
      , description: req.body.description
      });
    })
    .then(() => { res.end(); });
    .catch(next);
  }
 
, remove: (req, res, next) => {
    project(req).findById(req.params.id)
    .then((row) => row ? row.destroy() : Promise.resolve())
    .then(() => { res.end(); });
    .catch(next);
  }
};

Methods

route(app[, opts]) -> Promise

Routes controller modules for app which must be an Express instance.

opts is an object which may have the following properties:

• controllers: String [Default: path.join(process.cwd(), 'controllers')]
  Physical path to where controllers are implemented.

• url: String [Default: '/']
  Virtual path prefix for the controllers.

• index: String [Default: 'index']
  Controller's name which will be mapped directly onto url.

• authorizer: Function [Default: undefined]
  Middleware for user authorization.

• templates: Object [Default: { crud: [...] }]
  Templates for routes.

Each controller module implemented in opts.controllers directory will be mapped onto opts.url. You don't have to code for routing by yourself. Just maintain APIs structure as physical directory structure.

If you call route() once, which means you have only one controller directory, REST API is going to be flat like /api/<controllers>.

You can also call route() more than once to provide structured REST API. For example, if you want to seperate APIs by version like /api/v1/<controllers> and /api/v2/<controllers>, create two controller directories controllers/v1 and controllers/v2, then call route() as follow:

// app.js
 
'use strict';
 
const path = require('path')
    , express = require('express')
    , exprest = require('exprest4')
    , app = express()
    , api_versions = [1, 2]
    , controllers_dir = path.join(process.cwd(), 'controllers')
;
 
Promise.all(
  api_versions.map((version) => {
    return exprest.route(app, {
             url: '/api/v'+version
           , controllers: path.join(controllers_dir, 'v'+version)
           });
  })
)
.then(() => {
  app.listen();
});

If your REST APIs require users to be authenticated and/or to be authorized, opts.authorizer is the right place to implement user authentication/authorization feature. You can specifiy a middleware as opt.authorizer to verify a user session, then it will be called at first for every controller. The following example uses connect-ensure-login as opt.authorizer:

// app.js
 
'use strict';
 
const path = require('path')
    , express = require('express')
    , exprest = require('exprest4')
    , app = express()
    , ensureLoggedIn = require('connect-ensure-login').ensureLoggedIn
;
 
exprest.route(app, {
    url: '/api'
  , authorizer: ensureLoggedIn('/login')
})
.then(() => {
  app.listen();
});

model([opts]) -> Promise

Imports models into a Sequelize instance.

opts is an object which may have the following properties:

• models: String [Default: path.join(process.cwd(), 'models')]
  Physical path to where models are implemented.

• database: String [Default: undefined]
  Database name.

• username: String [Default: undefined]
  Username for database authentication.

• password: String [Default: undefined]
  Password for database authentication.

Each model module implemented in opts.models directory will be imported into a Sequelize instance after connection to a database is established. The Sequelize instance will be returned with Promise upon success. If a model module has associate() as a part of classMethods, it will be called with sequelize.models as its argument after all models are loaded. So that it allows you to define associations between models.

opts.database, opts.username and opts.password are passed to Sequelize's constructor. Other options are also passed through to options, the 4th arugment of Sequelize's constructor.

model.connect([opts]) -> Promise

Connects to a database through Sequelize by calling Sequelize.authenticate().

opts is an object which may have the following properties:

• database: String [Default: undefined]
  Database name.

• username: String [Default: undefined]
  Username for database authentication.

• password: String [Default: undefined]
  Password for database authentication.

The Sequelize instance will be returned with Promise upon success.

Each property of opts is passed to Sequelize's constructor. Other options are also passed through to options, the 4th arugment of Sequelize's constructor.

model.sync([opts]) -> Promise

Synchronizes all defined models to a database.

opts is an object which may have the following properties:

• models: String [Default: path.join(process.cwd(), 'models')]
  Physical path to where models are implemented.

• database: String [Default: undefined]
  Database name.

• schema: String [Default: undefined]
  Schema name.

• username: String [Default: undefined]
  Username for database authentication.

• password: String [Default: undefined]
  Password for database authentication.

The Sequelize instance will be returned with Promise upon success.

opts.database, opts.username and opts.password are passed to Sequelize's constructor. Other options are also passed through to options of both Sequelize's constructor and Sequelize.sync().

Note that this function is equivalent to Sequelize.sync() unless Sequelize connects to PostgreSQL database. There is an issue in Sequelize.sync() for PostgreSQL, even if options.schema is specified, no schema is prepended to table names while executing dropTable(). So that the tables under the public schema with the same names as your models might be dropped unintentionally by Sequelize.sync(). This function provides workaround for the issue.

opts.schema is passed to each model module implemented in opts.models directory as the third argument. The model modules have to pass the schema as options.schema to Sequelize.define() as the following example:

// models/project.js
 
'use strict';
 
module.exports = (sequelize, DataTypes, schema) => {
  return sequelize.define('project', {
    title: DataTypes.STRING
  , description: DataTypes.TEXT
  }, {
    schema: schema
  });
};

__exprest Property

routes : Array [Required]

Each element is an object which has the following properties:

• action: String [Required]
  Function name to be routed.

• method: String [Default: 'get']
  Request method to be routed.

• path: String [Default: '']
  Virtual path for the action.

• authorized: Boolean [Default: true]
  Authorization is required or not for the action.

• validator: Object [Default: undefined]
  Validator(s) for placeholders in path.

• middleware: {Function|Function[]} [Default: undefined]
  Middleware(s) to be passed to Express.

preset : Object [Default: undefined]

The following properties will be applied to each element in routes:

• authorized: Boolean [Default: true]
  Authorization is required or not. This can be overwritten by routes[].authorized.

• validator: Object [Default: undefined]
  Validator(s) for placeholders in each path.

• middleware: {Function|Function[]} [Default: undefined]
  Middleware(s) to be passed to Express.

• template: String [Default: undefined]
  One of templates to be used as routes.

Validator

If routes[].path contains any placeholders to receive parameters from req.params object, validator will be helpful to validate parameters before calling routes[].action. The following example uses validator.js as validator:

const validator = require('validator');
 
'use strict';
 
module.exports = {
  __exprest: {
    routes: [{
      action: 'view'
    , path: ':id'
    , validator: {
        id: validator.isNumeric
      }
    }]
  }
 
, view: (req, res) => {
    // `req.params.id` must a number.
    res.json({ id: req.params.id });
  }

You can also use a RegExp object instead of a function as follow:

'use strict';
 
module.exports = {
  __exprest: {
    routes: [{
      action: 'view'
    , path: ':id'
    , validator: {
        id: /^[1-9][0-9]*/
      }
    }]
  }
 
, view: (req, res) => {
    // `req.params.id` must a number.
    res.json({ id: req.params.id });
  }

If you have a placeholder commonly used in a controller, you can use preset.validator as follow:

'use strict';
 
const validator = require('validator');
 
module.exports = {
  __exprest: {
    preset: {
      validator: {
        id: validator.isNumeric
      }
    }
  , routes: [
      action: 'view'
    , path: ':id'
    }, {
      action: 'update'
    , path: ':id'
    , method: 'put'
    }, {
      action: 'remove'
    , path: ':id'
    , method: 'delete'
    }]
  }
 
, view: (req, res) => {
    res.json({ action: 'view', id: req.params.id });
  }
 
, update: (req, res) => {
    res.json({ action: 'update', id: req.params.id });
  }
 
, remove: (req, res) => {
    res.json({ action: 'remove', id: req.params.id });
  }
};

Middleware

middleware is typically used for APIs accept file uploading. The following example uses Multer as middleware:

'use strict';
 
const multer = require('multer')
    , upload = multer(/* memory storage */)
;
 
module.exports = {
  __exprest: {
    routes: [{
      action: 'echo'
    , method: 'post'
    , middleware: upload.single('message')
    }]
  }
 
, echo: (req, res) => {
    res.json({ echo: req.file.buffer.toString() });
  }
};

Another use case is authentication. The following example uses Passport as middleware:

'use strict';
 
const passport = require('passport');
 
module.exports = {
  __exprest: {
    routes: [{
      action: 'login'
    , middleware: passport.authenticate('basic', { session: false })
    }]
  }
 
, login: (req, res) => {
    res.json({ loginAs: req.user.username });
  }
};

If you want to authenticate users for every action in a controller, you can use preset.middleware as follow:

'use strict';
 
const passport = require('passport')
    , multer = require('multer')
    , upload = multer(/* memory storage */)
;
 
module.exports = {
  __exprest: {
    preset: {
      middleware: passport.authenticate('basic', { session: false })
    }
  , routes: [{
      action: 'login'
    }, {
      action: 'echo'
    , method: 'post'
    , middleware: upload.single('message')
    }]
  }
 
, login: (req, res) => {
    res.json({ loginAs: req.user.username });
  }
 
, echo: (req, res) => {
    res.json({ echo: req.file.buffer.toString() });
  }
};

Template

template is an option to avoid defining the same routes in multiple controllers. Once you define routes which might be used often in several controllers, then feed them to route() with opts.templates, each controller can refer one of the templates through preset.template property. The following example shows how to use template:

// app.js
 
'use strict';
 
const express = require('express')
    , exprest = require('exprest4')
    , app = express()
    , templates = {
        queue: [{
          action: 'push'
        , path:   ':elem'
        , method: 'post'
        }, {
          action: 'pop'
        , method: 'delete'
        }]
      }
;
 
exprest.route(app, { templates: templates })

// controllers/seat.js
 
'use strict';
 
let waiting_list = [];
 
module.exports = {
  __exprest: {
    preset: {
      template: 'queue'
    }
    // No routes required here.
  }
 
, push: (req, res) => {
    waiting_list.push(req.params.elem);
    res.json(waiting_list);
  }
 
, pop: (req, res) => {
    waiting_list.pop();
    res.json(waiting_list);
  }
};

exprest4 provides the following template crud by default which might be useful for CRUD-based REST APIs:

[{
    action: 'list'
}, {
    action: 'view'
  , path:   ':id'
}, {
    action: 'create'
  , method: 'post'
}, {
    action: 'update'
  , path:   ':id'
  , method: 'put'
}, {
    action: 'remove'
  , path:   ':id'
  , method: 'delete'
}]

If you define routes along with preset.template, each route in routes will be appended to the template routes as a result. In addition, routes which has exactly the same method and path overwrites corresponding routes in the template.

License

The MIT License (MIT)

Copyright (c) 2016-2018 Hiro Fujita [e-mail]

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.