Request parsing in Svelte

Introduction

Request parsing helps your app understand data sent by users or other systems. It turns raw request info into usable values.

When you want to get form data submitted by a user.

When you need to read query parameters from a URL.

When handling JSON data sent from a client.

When processing file uploads in a form.

When building APIs that accept data from other apps.

Syntax

Svelte

export async function POST({ request }) {
  const data = await request.json();
  // use data here
  return new Response('Received');
}

Use request.json() to parse JSON body data.

For form data, use request.formData().

Examples

Parse JSON data from a POST request and respond with a greeting.

Svelte

export async function POST({ request }) {
  const jsonData = await request.json();
  return new Response(`Hello, ${jsonData.name}`);
}

Parse form data and extract the 'email' field.

Svelte

export async function POST({ request }) {
  const formData = await request.formData();
  const email = formData.get('email');
  return new Response(`Email received: ${email}`);
}

Parse query parameters from the URL in a GET request.

Svelte

export async function GET({ url }) {
  const search = url.searchParams.get('search');
  return new Response(`Search query: ${search}`);
}

Sample Program

This SvelteKit endpoint parses JSON data sent in a POST request. It reads the 'name' and 'message' fields and responds with a friendly message.

Svelte

export async function POST({ request }) {
  const data = await request.json();
  const message = `Hello, ${data.name}! You sent: ${data.message}`;
  return new Response(message);
}

Important Notes

Always await request.json() or request.formData() because they return promises.

Check the request method (GET, POST) to decide how to parse data.

Use url.searchParams to read query strings in GET requests.

Summary

Request parsing turns raw request data into usable values.

Use request.json() for JSON and request.formData() for form data.

Query parameters come from url.searchParams.