Loopback Boot Scripts

Introduction

Loopback Boot Scripts is collection of useful boot scripts for Loopback framework.

Each boot script can be individually enabled / disabled and also it's behavior can be configured to an extent.

Installation

npm install loopback-boot-scripts --save

OR

yarn add loopback-boot-scripts

Modify server.js file as below. This will make the boot-scripts files run first and then boot files in the server/boot directory.

let bootOptions = {
  'appRootDir': __dirname,
  'bootDirs': [
    './node_modules/loopback-boot-scripts/dist/'
  ]
};

...


boot(app, bootOptions, function(err) {
  if (err) throw err;

  // start the server if `$ node server.js`
  if (require.main === module)
    app.start();
});

Boot Scripts

Custom Errors

Inspired from https://gist.github.com/justmoon/15511f92e5216fa2624b.

Creates Error classes for various HTTP error codes as default Node.js Error class does not capture statusCode and code.

Configuration

"bootScripts": {
  "customErrors": {
    "errors": [
      {"statusCode": 400, "code": "BAD_REQUEST"}
    ],
    "mode": "merge"
  }
}

In above example, a new class BadRequestError will be created with default statusCode=400 and code=BAD_REQUEST.

mode parameter can have a truthy value merge or anything else as falsy. If mode = merge i.e. truthy, errors given with config will be merged with default errors in errors.json, else default errors will be overwritten.

Global Promise

Simply replaces native Promise with bluebird Promise.

Global Models

Accessing models within loopback can be tedious at times. This boot script simply brings all models to global scope for easy reference.

Find By Property

Adds findBy{Property} and findOneBy{Property} methods to models.

e.g.

{
  "name": "Contact",
  "base": "PersistedModel",
  "idInjection": true,
  "properties": {
    "name": {
      "type": "string"
    },
    "mobile": {
      "type": "string"
    },
    "email": {
      "type": "string"
    }
  }
}

For the above model, following new methods will be added.

Contact.findByName
Contact.findByMobile
Contact.findByEmail

Contact.findOneByName
Contact.findOneByMobile
Contact.findOneByEmail

Please note that since findById method already exists, it won't be overwritten. In that sense, if any of the dynamic generated method already exists in model, it won't be overwritten.

Configuration

In case if either find or findOne methods are not required, they can be disabled with following config.

"bootScripts": {
  "findByProperty": {
    "find": false,
    "findOne": false
  }
}

Current User

Adds a user instance into context accessible at ctx.args.options.[KEY] where [KEY] defaults to currentUser but can also be configured.

User model is also configurable.

Configuration

"bootScripts": {
  "currentUser": {
    "key": "user",
    "model": "CustomUser"
  }
}

Token Refresh

A general use case is where token needs to expire after certain days of last access. This requires refreshing token expiry after every access.

Refreshing the token in every request is also costly, thus this boot script takes care of refreshing token onceIn specified time frame by given ttl.

Configuration

"bootScripts": {
  "tokenRefresh": {
    "onceIn": 86400 * 2,
    "ttl": 86400 * 7
  }
}

Above config will refresh token once in 2 days and will set ttl as 7 days.

Enable / Disable

Each boot script is by default enabled. Need be, it can be disabled by either of following ways.

Let's disable Custom Errors for example.

"bootScripts": {
  "customErrors": false
}

OR

"bootScripts": {
  "customErrors": {
    "enabled": false
  }
}