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LibraryRequest and response objects in API routes

Request and response objects in API routes

Learn about Request and response objects in API routes as part of Next.js 14 Full-Stack Development

Table of Contents

Understanding Request and Response Objects in Next.js API Routes

In Next.js, API routes are serverless functions that allow you to build your backend logic directly within your Next.js application. When a request hits an API route, the server provides two crucial objects:

code
request
and
code
response
. Understanding how to interact with these objects is fundamental to handling incoming data and sending back appropriate results.

The Request Object

The

code
request
object contains all the information about the incoming client request. This includes details like the HTTP method used (GET, POST, PUT, DELETE, etc.), headers, query parameters, and the request body.

The Request object is your window into what the client is sending.

It provides access to method, headers, query params, and the body of the incoming request.

The request object, often destructured as { request } or { req } depending on the Next.js version and specific API route handler signature, allows you to inspect various aspects of the client's request. For example, request.method tells you the HTTP verb, request.headers is an object containing all request headers, request.url provides the full URL, and request.query (in App Router) or request.url parsed for query parameters (in Pages Router) gives you access to URL parameters. For POST or PUT requests, the request.body property (which needs to be parsed, e.g., using request.json()) contains the data sent by the client.

What are the primary pieces of information you can access from the request object in a Next.js API route?

HTTP method, headers, URL, query parameters, and the request body.

The Response Object

The

code
response
object is used to construct and send back the server's reply to the client. You use its methods to set the status code, headers, and send the response body.

The Response object is how the server communicates back to the client.

It allows you to set status codes, headers, and send data back.

The response object, often destructured as { response } or { res }, is your tool for crafting the server's reply. Key methods include response.status(statusCode) to set the HTTP status code (e.g., 200 for OK, 404 for Not Found, 500 for Internal Server Error), response.setHeader(name, value) to add custom headers, and response.json(data) or response.send(data) to send the response body, typically as JSON. In the App Router, you typically return an object that Next.js automatically converts into a response.

In the Next.js App Router, you don't directly manipulate a response object in the same way as the Pages Router. Instead, you return a Response object or a plain JavaScript object that Next.js serializes into a response.

Integrating Request and Response in Full-Stack Development

Full-stack integration involves using the

code
request
object to receive data from the client (e.g., form submissions, API calls from the frontend) and then processing that data on the server. Based on the processing, you use the
code
response
object to send back results, status messages, or updated data to the frontend.

Consider a simple API route that accepts a POST request with a user's name in the request body. The API route will parse the request body to get the name, then use the response object to send back a personalized greeting. This demonstrates the core flow: receive data via request, process it, and send a tailored response via response.

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Text-based content

Library pages focus on text content

FeatureRequest ObjectResponse Object
PurposeReceive incoming client dataSend server reply to client
Key InformationMethod, Headers, Body, URL, Query ParamsStatus Code, Headers, Body
Primary ActionsInspect and parse dataSet status, headers, send data
Next.js App Router HandlingAccessed via function parameters (e.g., request)Constructed by returning a Response object or plain object

Example: Handling a POST Request

Let's look at a conceptual example of how you might handle a POST request in an API route. In the App Router, this often involves a

code
POST
function within a route handler file.

Loading diagram...

This flow highlights how the

code
request
object is the entry point for data, and the
code
response
object is the exit point for results. Mastering these two objects is key to building robust full-stack applications with Next.js.

Learning Resources

Next.js API Routes Documentation(documentation)

Official Next.js documentation on route handlers, covering request and response patterns in the App Router.

MDN Web Docs: Request(documentation)

Comprehensive documentation on the Request API, detailing its properties and methods.

MDN Web Docs: Response(documentation)

Detailed information about the Response API, essential for constructing server replies.

Understanding Next.js API Routes(blog)

A practical guide explaining how to create and use API routes in Next.js, with examples.

Building a Full-Stack App with Next.js 13 (App Router)(video)

A video tutorial demonstrating full-stack development with Next.js, including API route interactions.

Next.js API Routes: A Complete Guide(video)

A detailed video walkthrough of Next.js API routes, covering request and response handling.

HTTP Request Methods(documentation)

Explains the different HTTP methods (GET, POST, PUT, DELETE, etc.) used in client-server communication.

HTTP Status Codes(documentation)

A reference for understanding various HTTP status codes and their meanings.

Working with Request Body in Node.js(tutorial)

Covers how to handle request bodies in Node.js, which is relevant for Next.js API routes.

Next.js App Router: Route Handlers Explained(video)

A focused video tutorial specifically on Route Handlers in the Next.js App Router.