# Middlewares

@Middleware() is similar to the Express middleware with the difference that it's a class and you can use the IoC to inject other services on his constructor.

All middlewares decorated by @Middleware or @MiddlewareError have one method named use(). This method can use all parameters decorators as you could see with the Controllers and return promise.

# Installation

To begin, you must adding the middlewares folder on componentsScan attribute in your server settings as follow :

import {ServerLoader} from "@tsed/common";
import Path = require("path");
const rootDir = Path.resolve(__dirname);

@ServerSettings({
   rootDir,
   mount: {
      '/rest': `${rootDir}/controllers/**/**.js`
   },
   componentsScan: [
       `${rootDir}/services/**/**.js`,
       `${rootDir}/middlewares/**/**.js`
   ]
})
export class Server extends ServerLoader {

}

Then, create a new file in your middlewares folder. Create a new Class definition then add the @Middleware() or @MiddlewareError() annotations on your class.

You have different use cases to declare and use a middleware. Theses use cases are following:

• Global Middleware, this middleware can be used on ServerLoader,
• Global MiddlewareError, this middleware error can be used on ServerLoader,
• Endpoint Middleware, this middleware can be used on a controller method,
• Endpoint Middleware Error, this middleware can be used on a controller method.

# Specifics parameters decorators

In addition, you have this specifics parameters decorators for the middlewares: