In Nest.js, decorators are used to define metadata for various aspects of your application, including request handling. Let's break down each of the decorators for handling Nest.js Request.

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1.@Param(key?: string)

• Description: This decorator is used to extract parameters from the request URL.
• Usage: It can be applied to method parameters in a controller class to capture specific parameters from the URL.
• Example:

@Get('/param/:id')getParam(@Param('id')id:string){return`Param ID:${id}`;}

In this example, the:id in the route will be captured and passed to thegetParam method.

2.@Body(key?: string)

• Description: Used to extract data from the request body.
• Usage: Apply it to a method parameter to receive data from the body of a POST or PUT request.
• Example:

@Post()postBody(@Body()body:any){return`Body Data:${JSON.stringify(body)}`;}

This example expects a JSON object with a keydata in the request body.

3.@Query(key?: string)

• Description: Extracts parameters from the query string in the URL.
• Usage: Apply it to a method parameter to capture query parameters.
• Example:

@Get()getQuery(@Query()query:any){return`Query Parameter:${JSON.stringify(query)}`;}

If the URL is/example?name=Shameel, thegetQuery method will receive{name=:shameel}.

4.@Headers(name?: string)

• Description: Extracts values from the request headers.
• Usage: Apply it to a method parameter to get a specific header value.
• Example:

@Get('/header/')getHeaders(@Headers()headers:any){return`Header:${JSON.stringify(headers)}`;}

This example extracts the value of theauthorization header.

5.@Ip()

• Description: Retrieves the client's IP address from the request.
• Usage: Apply it to a method parameter to get the client's IP.
• Example:

@Get('ip')getIp(@Ip()ip:string){return`Client IP:${ip}`;}

This example retrieves the IP address of the client making the request.

Complete Controller Code

import{Body,Controller,Get,Ip,Param,Post,Query,Headers,}from'@nestjs/common';@Controller('request')exportclassRequestController{@Get('/param/:id')getParam(@Param('id')id:string){return`Param ID:${id}`;}@Post()postBody(@Body()body:any){return`Body Data:${JSON.stringify(body)}`;}@Get()getQuery(@Query()query:any){return`Query Parameter:${JSON.stringify(query)}`;}@Get('/header/')getHeaders(@Headers()headers:any){return`Header:${JSON.stringify(headers)}`;}@Get('ip')getIp(@Ip()ip:string){return`Client IP:${ip}`;}}

These decorators simplify the process of handling different parts of the HTTP request in your Nest.js application by providing a clean and structured way to access request parameters, body, headers, IP address, and host parameters.

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