Extending express-validator/node-validator to work with req.files

Question

Extending express-validator/node-validator to work with req.files

I'm trying to extend expressValidator to add my custom rule for checking if req.files is coming in as an image. Because express-validator uses node-validator, and node-validator parses the request body for the input parameter:

req.body.email is passed in as req.assert('email', 'Please enter a valid Email').isEmail(), so anything passed into req.assert() with express-validator needs to be the parameter name.

This is where I'm running into a problem, because I have my method I wrote here:

  expressValidator.Validator.prototype.isImage = function() {
    var type          = this.str,
        allowedTypes  = ['gif', 'jpg', 'jpeg', 'png'],
        allowed       = false;
    for (var i = 0; i < allowedTypes.length; i++) {
      if (type.indexOf(allowedTypes[i]) !== -1) {
        allowed = true;
      }
    }

    if (!allowed) {
      this.error(this.msg);
    }
    return this;
  };

But I can't just do req.assert('avatar', 'Please enter a valid image type').isImage() because for one, I need to pass in the req.files.avatar.type. With req.assert(), the first parameter expects a string.

If I do give it the string: e.g. req.assert(req.files.avatar.type, 'Please enter a valid image type').isImage() in my error message object, it'll show this:

{ 'image/png':
   { param: 'image/png',
     msg: 'Please enter a valid image',
     value: undefined } 
}

When it should be showing this:

{ 'avatar':
   { param: 'avatar',
     msg: 'Please enter a valid image',
     value: 'image/png' } 
}

javascript
node.js
validation
express

Answer 1

Recently I did something similar. But my approach is a little different, more kinda hack. But since no one answered, I will try to help :)

I wrote a generic error generation vaildator.prototype

expressValidator.Validator.prototype.genError = function() {
  this.error(this.msg);
  return this;
};

Then while validating,

var validate_profile = function(req, next) {
  async.series([
    function(callback) {
      req.assert('name', 'Please provide your name.').notEmpty().notNull();
      .........
    },
function(callback) {
  // Validate image size for profile_picture
  if(req.files.profile_picture && req.files.profile_picture.size === 0) {
    req.assert('profile_picture', 'Profile picture is required').genError();
  }
  if(req.files.profile_picture && req.files.profile_picture.size > 0) {
    imageMagick(req.files.profile_picture.path).size(function(err, size) {
    if (err) throw err;
    if(size.width < 1200) {
      req.assert('profile_picture', 'Profile picture should have atleast 1200px width').genError();
      callback(null);
    } else callback(null);
    .......

This works for me perfectly. Your approach is of-course better, but this works as well :)