Server routes and API in Vue

Introduction

Server routes let your app talk to a server to get or send data. APIs are like menus that show what data you can ask for or send.

When you want to load user info from a server to show on your page.

When you need to save a form's data to a database.

When your app needs to get updated info without reloading the whole page.

When you want to connect your frontend app with backend services.

When you want to build features like login, comments, or live updates.

Syntax

Vue

import { defineEventHandler } from 'h3'

export default defineEventHandler(async (event) => {
  // Your code to handle the request
  return { message: 'Hello from API' }
})

This example shows a simple server route handler in a Vue 3 + Nitro environment (like Nuxt 3).

Server routes are placed in the server/api folder and automatically become API endpoints.

Examples

A simple GET route that returns a greeting message as JSON.

Vue

export default defineEventHandler(() => {
  return { greeting: 'Hi there!' }
})

This route reads data sent by the client and sends it back in the response.

Vue

import { readBody } from 'h3'

export default defineEventHandler(async (event) => {
  const body = await readBody(event)
  return { received: body }
})

Returns the current server time as a string.

Vue

export default defineEventHandler(() => {
  return { time: new Date().toISOString() }
})

Sample Program

This server route handles POST requests. It reads the JSON body sent by the client, extracts the name field, and replies with a greeting message. If the request is not POST, it tells the client what to do.

Vue

import { defineEventHandler, readBody } from 'h3'

export default defineEventHandler(async (event) => {
  if (event.node.req.method === 'POST') {
    const data = await readBody(event)
    return { message: `Hello, ${data.name}!` }
  }
  return { message: 'Send a POST request with { name } in JSON.' }
})

Important Notes

Server routes run only on the server, so you can safely handle secrets or database calls here.

Use readBody(event) to get data sent by the client in POST or PUT requests.

Server routes in Vue/Nuxt are automatically available based on their file path under server/api.

Summary

Server routes let your app communicate with backend logic and data.

APIs define how your frontend and backend talk using requests and responses.

In Vue with Nitro, server routes are simple functions that handle requests and return JSON.

Practice

1. What is the main purpose of server routes in a Vue app using Nitro?

easy

A. To style the frontend components

B. To handle backend requests and send responses

C. To manage client-side state only

D. To create animations on the page

Solution

1. Step 1: Understand server routes role

   Server routes act as backend endpoints that receive requests from the frontend.

2. Step 2: Identify their function in Vue Nitro

   They process these requests and return data or responses, enabling communication between frontend and backend.

3. Final Answer:

   To handle backend requests and send responses -> Option B

4. Quick Check:

   Server routes = backend communication [OK]

Hint: Server routes handle backend requests, not frontend styling [OK]

Common Mistakes:

• Confusing server routes with frontend styling
• Thinking server routes manage only client state
• Assuming server routes create animations

2. Which of the following is the correct way to define a server route in a Vue Nitro project?

easy

A. app.get('/api', () => 'Hello')

B. const route = () => { console.log('Hello') }

C. export default defineEventHandler(() => { return { message: 'Hello' } })

D. function serverRoute() { return 'Hello' }

Solution

1. Step 1: Recognize Nitro server route syntax

   In Vue Nitro, server routes export a default function using defineEventHandler that returns data.

2. Step 2: Check each option

   export default defineEventHandler(() => { return { message: 'Hello' } }) uses defineEventHandler and returns an object, which is correct. Others either lack export, use wrong syntax, or are not Nitro style.

3. Final Answer:

   export default defineEventHandler(() => { return { message: 'Hello' } }) -> Option C

4. Quick Check:

   Use defineEventHandler for Nitro routes [OK]

Hint: Look for export default with defineEventHandler [OK]

Common Mistakes:

• Missing export default
• Not using defineEventHandler
• Using Express.js style instead of Nitro

3. Given this server route code in Vue Nitro:

export default defineEventHandler(() => { return { status: 'ok', count: 5 } })

What will the frontend receive when calling this API?

medium

A. Undefined

B. A string 'ok5'

C. An error because of missing await

D. { status: 'ok', count: 5 }

Solution

1. Step 1: Analyze the returned object

   The route returns an object with keys status and count, so the response is JSON with those values.

2. Step 2: Understand Nitro response behavior

   Nitro automatically serializes the returned object to JSON for the frontend.

3. Final Answer:

   { status: 'ok', count: 5 } -> Option D

4. Quick Check:

   Returned object = JSON response [OK]

Hint: Returned object becomes JSON response automatically [OK]

Common Mistakes:

• Expecting string concatenation
• Thinking await is needed for sync return
• Assuming undefined if no explicit JSON

4. What is wrong with this Vue Nitro server route code?

export default () => { return { message: 'Hi' } }

medium

A. Missing defineEventHandler wrapper

B. Return value must be a string

C. Export default is not allowed

D. Arrow function syntax is invalid

Solution

1. Step 1: Check Nitro route requirements

   Vue Nitro requires server routes to export a default function wrapped with defineEventHandler.

2. Step 2: Identify missing part

   The code exports a function but does not use defineEventHandler, so it won't work as a proper Nitro route.

3. Final Answer:

   Missing defineEventHandler wrapper -> Option A

4. Quick Check:

   Always wrap route with defineEventHandler [OK]

Hint: Always use defineEventHandler for server routes [OK]

Common Mistakes:

• Forgetting defineEventHandler
• Thinking return must be string
• Confusing export default rules

5. You want to create a server route in Vue Nitro that returns a list of users filtered by a query parameter `role`. Which code correctly accesses the query and returns filtered users?

hard

A. export default defineEventHandler(event => { const role = getQuery(event).role; return users.filter(u => u.role === role) })

B. export default defineEventHandler(() => { return users })

C. export default defineEventHandler(event => { const role = event.node.req.url.split('role=')[1]; return users.filter(u => u.role === role) })

D. export default defineEventHandler(event => { const role = event.query.role; return users.filter(u => u.role === role) })

Solution

1. Step 1: Understand query access in Nitro

   Vue Nitro provides a helper getQuery(event) to safely get query parameters from the request.

2. Step 2: Check each option for correct query usage

   export default defineEventHandler(event => { const role = getQuery(event).role; return users.filter(u => u.role === role) }) uses getQuery(event).role correctly. export default defineEventHandler(event => { const role = event.node.req.url.split('role=')[1]; return users.filter(u => u.role === role) }) manually parses URL which is error-prone. export default defineEventHandler(() => { return users }) ignores query. export default defineEventHandler(event => { const role = event.query.role; return users.filter(u => u.role === role) }) uses event.query which is not standard.

3. Final Answer:

   export default defineEventHandler(event => { const role = getQuery(event).role; return users.filter(u => u.role === role) }) -> Option A

4. Quick Check:

   Use getQuery(event) to read query params [OK]

Hint: Use getQuery(event) to access query parameters [OK]

Common Mistakes:

• Parsing URL manually instead of getQuery
• Using event.query which is undefined
• Ignoring query parameters