Error: Can't set headers after they are sent in middleware for joi validation

Question

我已经创建了一个用于 joi 验证错误处理的中间件，但它 returns 带有一些警告，例如 '错误：发送后无法设置 headers'

错误：

Error: Can't set headers after they are sent.
    at validateHeader (_http_outgoing.js:491:11)
    at ServerResponse.setHeader (_http_outgoing.js:498:3)
    at ServerResponse.header (D:\nodejs\bigfish\node_modules\express\lib\response.js:767:10)
    at ServerResponse.send (D:\nodejs\bigfish\node_modules\express\lib\response.js:170:12)
    at ServerResponse.json (D:\nodejs\bigfish\node_modules\express\lib\response.js:267:15)
    at Object.JSONResponse [as JR] (D:\nodejs\bigfish\helpers\JsonResponse.js:3:29)
    at module.exports (D:\nodejs\bigfish\middlewares\error.js:8:14)
    at newFn (D:\nodejs\bigfish\node_modules\express-async-errors\index.js:12:20)
    at Layer.handle_error (D:\nodejs\bigfish\node_modules\express\lib\router\layer.js:71:5)
    at trim_prefix (D:\nodejs\bigfish\node_modules\express\lib\router\index.js:315:13)

..

const express = require('express');
const Joi = require('joi');
const router = express.Router();
const HelperJoi = require('../helpers/joivalidation');
router.get('/GetRetailerDetails',VerifyToken, async (req,res) => {
    //Start Validation Code
    const schema = {
        RetailerId: Joi.number().required(),
    };
    HelperJoi.validate(req,res,schema);
    //End of Validation code      
});

joivalidation.js helpers 文件夹下

const Joi = require('joi');
//This is Helper Function Module for Joi Validation
function JoiValidation(req,res,schema){
    const result = Joi.validate(req.query,schema, { abortEarly: false });
    if(result.error){
        //422 Validation Error
        var objError = [];    
        Object.keys(result.error.details).forEach(function(key) {
            objError.push(result.error.details[key]['message']);
        });
        return res.status(422).json({
            'statuscode': 422,
            'message': 'Validation Error',
            'responsedata': objError
        });
    }
}

module.exports.validate = JoiValidation

Answer 1

仅仅因为验证器函数 return 是错误情况下的响应并不意味着代码的其余部分不是运行。

所以需要回传给中间件验证失败，中间件不要继续

例如：

// middleware
if (! HelperJoi.validate(req,res,schema)) {
  // Validation failed, so we're done
  return;
}

// validator function
if (result.error) {
  ...
  res.status(422).json({
    'statuscode': 422,
    'message': 'Validation Error',
    'responsedata': objError
  });
  return false;
}
return true;

另一种解决方案是验证器函数将 return "null" 如果验证是肯定的，并且在验证失败的情况下是错误数组，中间件将 return 422 响应本身。这将解耦验证器功能。

Answer 2

HelperJoi.validate 是其中的一个函数，您发送响应然后 return 到作为路由处理程序的调用函数并表示尝试终止请求并设置为 headers 已经发送。使用验证作为中间件或 return 来自 HelperJoi.validate 的验证错误并从路由处理程序响应。

Answer 3

看起来你的实现是错误的。

示例：如何实施JOI验证

const express = require('express');
const router = express.Router();
const joiHelper = require('../helpers/joiHelper');
router.get('/GetRetailerDetails',VerifyToken, async (req,res) => {

   let validationResult = joiHelper.JoiValidation(req.query, joiHelper.getRetailSchema(), {allowUnknown: false});
    if (validationResult.error) {
      return res.status(422).json({
            'statuscode': 422,
            'message': 'Validation Error',
            'responsedata': joiHelper.parseError(validationResult.error.details)
        });
    }    

    //Proceeds your get request
});

joiHelper.js

const Joi = require('joi');

const joiHelper = {};

joiHelper.JoiValidation(object, schema, options = {}){
    return Joi.validate(object, schema, options);
};

joiHelper.parseError(errorObject) {
    let errorDetail = [];
    for (var key in errorObject) {
      errorDetail.push(errorObject[key].message);
    }
    return errorDetail.join(', ').replace(new RegExp('"','g'),'');
}
joiHelper.getRetailSchema () {
  const schemaObj = {
    RetailerId: Joi.number().required()
  };
  return Joi.object().keys(schemaObj);
};

module.exports = joiHelper;

Error: Can't set headers after they are sent in middleware for joi validation

Error: Can't set headers after they are sent in middleware for joi validation

node.js

express

joi