Multer and express-validator creating problem in validation

In theory, running categoryCreationRules and validate middlewares before multer would be enough. Therefore, you would only need a verification in the request body and if it contains any errors, you just return a bad request response, not letting the request pass to the next middleware (in this case the multer).

A simple example what i'm talking about: (Just to let it clear, the below code won't work)

router.post("/", categoryRules.categoryCreationRules(), validate, upload.upload('image').single('categoryLogo'), categoryController.createCategory);const validator = (req, res, next) => {  try {    validationResult(req).throw();    // Continue to next middleware, in this case, multer.    next();  } catch (errors) {    // return bad request    res.status(400).send(errors);  }};

this won´t work because your req.body will be undefined, as you are sending the data as a multipart/form-data (generally used to upload files). And in this case, errors will always be true.

But with multer this will not happen - you will be able to access body fields like description and name and then do the validation code.

This occurs because multer, internally, parses the multipart/form-data request to body with a library called busboy, and with this you can access fields through req.body.

Because of that, i think the best approach here is call multer middleware before your validations middlewares:

router.post("/", upload.upload('image').single('categoryLogo'), categoryRules.categoryCreationRules(), validate, categoryController.createCategory);

And after that, if the validation has an error, you delete the file created from multer and return a bad request response, something like that:

const fs = require("fs");const validator = (req, res, next) => {  try {    validationResult(req).throw();    // continue to next middleware    next();  } catch (errors) {    fs.unlink(req.file.path, (err) => {      if (err) {multipart/form-data        /* HANLDE ERROR */      }      console.log(`successfully deleted ${req.file.path}`);    });    // return bad request    res.status(400).send(errors);  }};

You can get more info about this in the below links:

node-js-with-express-bodyparser-unable-to-obtain-form-data-from-post-request

req-body-undefined-multipart

html-multipart-form-data-error-in-req-body-using-node-express

To upload an image , you have set the enctype of form to multipart/form-data . But if you use multer later, you don't have the form data parsed, hence probaby giving undefined.

Please check multiparty , an npm module

https://www.npmjs.com/package/multiparty

It also parses other fields along with file uploads and validation might be easy to set.