Fastify Resource

A way of creating RESTful CRUD resources for Fastify and Objection.js.

Dependencies

• Node.js
• Fastify
• Objection.js for models

Install

npm i @anephenix/fastify-resource

Usage

When writing code for an API, you may find yourself generating RESTful routes for Objection.js models that support CRUD operations (Create/Read/Update/ Delete).

This library provides a way to generate code that will provide that with a few lines of code.

For example, in Fastify you will usually define routes and handler functions for CRUD like this:

const fastify = require('fastify')({ logger: false });
const Asset = require('./models/Asset');

// GET /assets
fastify.get('/assets', async (req, rep) => {
  try {
    const data = await Asset.query();
    return data;
  } catch (error) {
    rep.statusCode(400);
    return error.message;
  }
});

// POST /assets
fastify.post('/assets', async (req, rep) => {
  try {
    const assets = await Asset.query().insert(req.body);
    rep.statusCode(201);
    return assets;
  } catch (error) {
    rep.statusCode(400);
    return error.message;
  }
});

// GET /assets/:id
fastify.get('/assets/:id', async (req, rep) => {
  try {
    const asset = await Asset.query().findById(req.params.id);
    if (asset) return asset;
    if (!asset) {
      res.statusCode(404);
      return 'Not found';
    }
  } catch (error) {
    rep.statusCode(400);
    return error.message;
  }
});

// PATCH /assets/:id
fastify.patch('/assets/:id', async (req, rep) => {
  try {
    const asset = await Asset.query().patchAndFetchById(
      req.params.id,
      req.body
    );
    if (asset) return asset;
    if (!asset) {
      res.statusCode(404);
      return 'Not found';
    }
  } catch (error) {
    rep.statusCode(400);
    return error.message;
  }
});

// DELETE /assets/:id
fastify.delete('/assets/:id', async (req, rep) => {
  try {
    await Asset.query().deleteById(req.params.id);
    return req.params.id;
  } catch (error) {
    rep.statusCode(400);
    return error.message;
  }
});

There's about 60 lines of code there for the routes. Now if you have a lot of resources that you want to generate a bunch of RESTful routes and CRUD actions for, then this file will become hundreds of lines of code at the very least. Also, you may find that you are repeating the same code but with different Objection.js models and routes in place.

With fastify resource, you can write this code and it will do the same thing:

const fastify = require('fastify')({ logger: false });
const Asset = require('./models/Asset');
const { resource, attach } = require('@anephenix/fastify-resource');

const { routes } = resource(Asset, 'asset');
attach({ fastify, routes });

The resource function is passed the Objection.js model as the 1st argument, and the name of the resource for generating the url routes from as the 2nd argument.

This will do the following:

• Define a list of 5 API RESTful routes that cover CRUD functions:

GET       /assets
POST      /assets
GET       /assets/:id
PATCH     /assets/:id
DELETE    /assets/:id

• It will create the controller actions that support those API routes
• It will also create a service module that serves the controller

To then attach those routes to the fastify app, we call the attach function and pass the fastify instance and routes to combine them.

This helps you to quickly assemble a REST API for your Objection.js models, using a few lines of code.

Route-Controller-Service pattern

The way that the library works is that it generates a set of objects that provide functions that can be called:

Route -> Controller -> Service -> Model

Route

The first is the set of routes, which when generated for a resource look something like this:

[
  { method: 'get', url: '/assets', handler: Function },
  { method: 'post', url: '/assets', handler: Function },
  { method: 'get', url: '/assets/:id', handler: Function },
  { method: 'patch', url: '/assets/:id', handler: Function },
  { method: 'delete', url: '/assets/:id', handler: Function },
];

Controller

The handler function is the controller action that will be called when the API route is called. The controller is accessible from the resource function call:

const { routes, controller, service } = resource(Asset, 'asset');

The generated controller code looks like this:

{
		index: async (req:Request, rep:Reply) => {
			const { success, data, error } = await service.getAll(req.params);
			return handleResponse({success,data,error, rep});
		},
		create: async (req:Request, rep:Reply) => {
			const params = Object.assign({}, req.params, req.body);
			const { success, data, error } = await service.create(params);
			return handleResponse({success,data,error, rep, successCode: 201});
		},
		get: async (req:Request, rep:Reply) => {
			const { success, data, error } = await service.get(req.params);
			return handleResponse({success,data,error, rep});
		},
		update: async (req:Request, rep:Reply) => {
			const params = Object.assign({}, req.params, req.body);
			const { success, data, error } = await service.update(params);
			return handleResponse({success,data,error, rep});
		},
		delete: async (req:Request, rep:Reply) => {
			const { success, data, error } = await service.delete(req.params);
			return handleResponse({success,data,error, rep});
		},
	};

The controller actions try to extract the relevant data from the HTTP request and pass it to the relevant service action. It then handles the response from the service, and returns the HTTP response suitable for it.

This makes the controller action essentially an interface to the service, and the service is where the business logic for the action is defined.

Service

The service is the core part of the application's business logic, and is the primary part of the code that interfaces with the Objection.js model. The generated code for the service looks like this:

{
    getAll: async (params:Params) => {
        try {
            const data = await model.query().where(params);
            return { success: true, data };
        } catch (error) {
            return { success: false, error };
        }
    },
    create: async (params:Params) => {
        try {
            const data = await model.query().insert(params);
            return { success: true, data };
        } catch (error) {
            return { success: false, error };
        }
    },
    get: async (params:Params) => {
        try {
            const data = await model.query().where(params);
            return { success: true, data };
        } catch (error) {
            return { success: false, error };
        }
    },
    update: async (params:Params) => {
        try {
            const updateParams = objectWithoutKey(params, 'id');
            const data = await model
                .query()
                .patchAndFetchById(params.id, updateParams);
            return { success: true, data };
        } catch (error) {
            return { success: false, error };
        }
    },
    delete: async (params:Params) => {
        try {
            await model.query().deleteById(params.id);
            return { success: true, data: params.id };
        } catch (error) {
            return { success: false, error };
        }
    },
};

Usually controller actions would be the primary code that interfaces with the Objection.js model (like in the MVC pattern), but by abstracting out that part into a service layer, you then have the opportunity to re-use those service actions with other interfaces, such as:

• A WebSocket API
• An interactive REPL
• A CLI tool

We essentially treat the controller actions as supporting a HTTP API interface to the service actions, alongside the other options.

Creating nested routes

Any REST API tends to implement a hierarchy of resources. Let's say for example there are 2 models - Post and Comment. A post has many comments, and we want to create an API that fits that relationship. We might want our comments API routes to be nested under the posts API routes.

The library can do that. In the resource function, you can pass an array of resources to assemble the API routes that fit that. Below is an example of how to do that:

const fastify = require('fastify')({ logger: false });
const Post = require('./models/Post');
const Comment = require('./models/Comment');
const { resource, attach } = require('@anephenix/fastify-resource');

const postResource = resource(Post, 'post');
const commentResource = resource(Comment, ['post', 'comment']);
attach({ fastify, routes: postResource.routes });
attach({ fastify, routes: commentResource.routes });

This will make the following API routes available on the fastify instance:

GET     /posts
POST    /posts
GET     /posts/:id
PATCH   /posts/:id
DELETE  /posts/:id

GET     /posts/:post_id/comments
POST    /posts/:post_id/comments
GET     /posts/:post_id/comments/:id
PATCH   /posts/:post_id/comments/:id
DELETE  /posts/:post_id/comments/:id

You can have many levels of nested resources in your code, it is not limited to any number (we just showed 2 resources in order to demonstrate the example).

Advanced usage

There might be cases where you need to do custom adjustments to the controller, or where you may want to access the service generated for the resource to attach other interfaces to.

Generating routes, controllers and services separately

The library allows you to generate the services, controllers and routes separately, so that you can structure your code in whatever pattern suits you.

The library has these functions available:

const {
  serviceGenerator,
  controllerGenerator,
  resourceRoutes,
} = require('@anephenix/fastify-resource');

serviceGenerator

The serviceGenerator function will generate a service for an Objection.js model.

controllerGenerator

The controllerGenerator function will generate a controller for a service.

resourceRoutes

The resourceRoutes function will generate the routes for a controller and the list of resources to turn into urls.

Using these will allow you to generate parts of the RCS pattern as well as make custom parts of that code if needed.

Tests

npm t

License and Credits

©2022 Anephenix OÜ. All Rights Reserved.