CODEWITHSUNDEEP
node.jsexpressmiddleware
username
username

Reputation: 159

Create a middleware to verify a response object before sending the response

I'm building a small CRUD app on the Express framework. I want to have a middleware that takes all my responses and verifies them against the expected object schemas. The issue what I'm currently facing is that I don't know where to put this middleware. I've tried to put it globally after my routes and the error handler middleware, but it didn't work for some reason. When I sticked it before my defined routes this middleware worked, but didn't have the required data from a route handler. I'm pretty familiar with the middleware concept in Express, but only for requests.

If you don't have a specific answer for this issue, please feel free to share your opinion if it helps to verify all outbound response. Thanks.

Any help is appreciated.

Upvotes: 0

Views: 1154

Answers (1)

Murat Colyaran
Murat Colyaran

Reputation: 2189

I can give you an example usage. You can modify the response object as you desire.



// ResponseHandler.js
// Creating a response object
class ResponseHandler{
    constructor(statusCode, body, success = 1){

      this.statusCode = statusCode;
      this.body = body;
      this.body.success = success ? success : (statusCode == 200 ? 1 : 0);
    }
  }
  
  module.exports = ResponseHandler;


// responseHandler.js
const ResponseHandler = require('./ResponseHandler');

const responseValidator = (err, req, res, next) => {
  let res = res;
  if (!(res instanceof ResponseHandler)) {
    const statusCode = res.statusCode;
    const body = res.body;
    const success = res.body.success;
    res = new ResponseHandler(statusCode, body, success);
  }

  next(res);
};

const responseHandler = (err, req, res, next) => {

    const response = responseValidator(res);

    res.status(response.statusCode).send(response.body);
};

module.exports = {
    responseHandler
};

// Usage

// In index.js (After defining your routes)
app.use(responseHandler);

// In controller
let res = {
    statusCode: 200,
    body: {
        success: 1, // Optinal
        message: "This is a success message."
    }
}
return next(res);

Upvotes: 1

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