400 Bad Request

The server couldn’t understand your request because the syntax is bad, the data is malformed, or it’s missing required fields.

When and Why to Use It

Use this when the client sends you garbage. E.g., they sent invalid JSON, they missed a required field, or their search query was formatted illegally. Do not use this for server crashes.

Usage Examples

Shokupan (Functional)

import { HttpException, post } from 'shokupan';

export const createUser = post('/users', (req) => {
    // Basic input validation
    if (!req.body || !req.body.email) {
        throw new HttpException('Missing required field: email', 400);
    }

    // ... create user
});

Shokupan (Controller)

import { Controller, Post, Body, HttpException } from 'shokupan';

@Controller('/api')
export class UserController {
    @Post('/users')
    createUser(@Body() body: any) {
        // Validation check
        if (!body.email) {
            throw new HttpException('Missing required field: email', 400);
        }

        // ... create user
    }
}

Express

import express from 'express';
const app = express();

app.post('/users', (req, res) => {
    // Validate request body
    if (!req.body?.email) {
        return res.status(400).json({ error: 'Missing required field: email' });
    }

    // ... create user
});

Nest

import { Controller, Post, Body, BadRequestException } from '@nestjs/common';

@Controller('users')
export class UserController {
  @Post()
  createUser(@Body() body: any) {
    // Usually Nest uses DTOs and ValidationPipes for this!
    if (!body.email) {
      throw new BadRequestException('Missing required field: email');
    }

    // ... create user
  }
}

Koa

import Koa from 'koa';
const app = new Koa();

// Assuming you're using koa-bodyparser
app.use(async ctx => {
  if (ctx.path === '/users' && ctx.method === 'POST') {
    const body = ctx.request.body;

    if (!body || !body.email) {
      ctx.status = 400;
      ctx.body = { error: 'Missing required field: email' };
      return;
    }

    // ... create user
  }
});