Express Plugin

The Express Plugin provides tools to work with the Express Framework to create Express applications in a better and organized way.

The plugin exposes decorators for creating controllers, route handlers, and middlewares that wraps the Express API.

This plugin should be used with Injex's Node runtime.

Installation

You can install the Env Plugin via NPM or Yarn.

npm install --save @injex/express-plugin

You should also make sure Express is installed on your project.

Initialization

Creating the plugin and passing it to the runtime container config object

import { Injex } from "@injex/node";
import { ExpressPlugin } from "@injex/express-plugin";
Injex.create({
rootDirs: [__dirname],
plugins: [
new ExpressPlugin({
// plugin configurations
})
]
});

Configurations

name

The express application instance name, as it will be used in the runtime container for later injection.

  • Type: string
  • Default: expressApp
  • Required: false

app

If you already have an express instance in your application, you can pass it to the app config option so the plugin will use it.

For example:

import { ExpressPlugin } from "@injex/express-plugin";
import * as express from "express";
const myApp = express();
const plugin = new ExpressPlugin({
app: myApp
})
  • Type: ExpressApplication instance
  • Default: null
  • Required: false

createAppCallback

If you don't provide the app config option, the Express Plugin will create an Express app instance for you. You can pass in the createAppCallback if you want to hook up the application instance with custom middleware or listen to a network port.

For example:

import { Injex } from "@injex/node";
import { ExpressPlugin } from "@injex/express-plugin";
import * as bodyParser from "body-parser";
Injex.create({
...
plugins: [
...
new ExpressPlugin({
createAppCallback: (app) => {
app.use(bodyParser());
app.listen(8080);
}
})
]
})
  • Type: Function
  • Default: function(app: Application) { }
  • Required: false

Usage

As mentioned above, the Express plugin exposes decorators to handle routes and middlewares inside a controller. A controller is a collection of route handlers related to a specific domain in your application. An exciting part about controllers is that they respond to the @singleton() decorator so that you can create a singleton controller or a factory-based controller made for each request.

@controller()

Defines a class and mark it as a controller. If the @singleton() decorator is also used, only one controller will be created for all requests; otherwise, a controller instance will be created for each request.

@define()
@controller()
export class TodosController {
}

@get(), @post(), @patch(), @put(), @del()

HTTP method handler decorators to define route handlers inside a controller.

@define()
@controller()
export class TodosController {
@get("/todos/:id")
public getTodo(req, res) {
res.send({
id: req.param.id,
text: "Learn how to use the Injex framework",
status: "in_progress"
});
}
}

@middleware()

Define a middleware or a list of chainable middlewares on a controller route handler. A middleware is a class that implements the IMiddleware interface.

Note that you can pass an array of middlewares (@middleware([ ... ])); in that case, the middlewares get called from left to right. If a middleware failed with an error, the route handler function would not be triggered.

@define()
@singleton()
export class AuthMiddleware implements IMiddleware {
// IMiddleware handler, receives express's request, response
// and the next function
public handle(req, res, next) {
const token = req.query.token;
if (token === "123456") {
next();
} else {
res.send("unauthorize");
next(new Error("unauthorize"));
}
}
}
@define()
@controller()
export class TodosController {
@get("/todos/:id")
@middleware(AuthMiddleware)
public getTodo(req, res) {
res.send({
id: req.param.id,
text: "Learn how to use the Injex framework",
status: "in_progress"
});
}
}

A full example

import { define, singleton } from "@injex/core";
import { controller, get, del, post, patch } from "@injex/express-plugin";
@define()
@singleton()
@controller()
export class TodosController {
@inject() private todosManager;
@get("/todos/")
public async getAllTodos(req, res) {
const todos = await this.todosManager.getAll();
res.send(todos);
}
@get("/todos/:id")
@middleware(AuthMiddleware)
public async getTodo(req, res) {
const todo = await this.todosManager.getOne(req.params.id);
res.send(todo);
}
@del("/todos/:id")
public async deleteTodo(req, res) {
await this.todosManager.del(req.params.id);
res.status(204).end();
}
@post("/todos/")
public async createTodo(req, res) {
const todo = await this.todosManager.create(req.params.id, req.body);
res.status(201).send(todo);
}
@patch("/todos/:id")
public async updateTodo(req, res) {
const todo = await this.todosManager.update(req.params.id, req.body);
res.send(todo);
}
@patch("/todos/:id/toggle")
public async toggleTodo(req, res) {
await this.todosManager.toggle(req.params.id);
res.status(201).end();
}
}

If you want a quick demo to play with, check out the express example in the examples section.

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