[file] How to limit the number of dropzone.js files uploaded?

Depending on the use case, how do I constrain the number of files that dropzone.js will allow?

For example, I might need to only allow 1, 2, or 4 files uploaded.

It's not uploadMultiple. Unfortunately, uploadMultiple only applies to the number of files handled per request.

Alternative solution that worked really well for me:

init: function() {
    this.on("addedfile", function(event) {
        while (this.files.length > this.options.maxFiles) {
            this.removeFile(this.files[0]);
        }
    });
}

I achieved this a slightly different way. I just remove the old dropped file any time a new file is added. It acts as overwriting the file which was the user experience I was going for here.

Dropzone.options.myAwesomeDropzone = {
  accept: function(file, done) {
    console.log("uploaded");
    done();
  },
  init: function() {
    this.on("addedfile", function() {
      if (this.files[1]!=null){
        this.removeFile(this.files[0]);
      }
    });
  }
};

You can limit the number of files uploaded by changing in dropezone.js

Dropzone.prototype.defaultOptions = { maxFiles: 10, }

it looks like maxFiles is the parameter you are looking for.

https://github.com/enyo/dropzone/blob/master/src/dropzone.coffee#L667

Why do not you just use CSS to disable the click event. When max files is reached, Dropzone will automatically add a class of dz-max-files-reached.

Use css to disable click on dropzone:

.dz-max-files-reached {
          pointer-events: none;
          cursor: default;
}

Credit: this answer

I'd like to point out. maybe this just happens to me, HOWEVER, when I use this.removeAllFiles() in dropzone, it fires the event COMPLETE and this blows, what I did was check if the fileData was empty or not so I could actually submit the form.

The problem with the solutions provided is that you can only upload 1 file ever. In my case I needed to upload only 1 file at a time (on click or on drop).

This was my solution..

    Dropzone.options.myDropzone = {
        maxFiles: 2,
        init: function() {
            this.handleFiles = function(files) {
                var file, _i, _len, _results;
                _results = [];
                for (_i = 0, _len = files.length; _i < _len; _i++) {
                    file = files[_i];
                    _results.push(this.addFile(file));
                    // Make sure we don't handle more files than requested
                    if (this.options.maxFiles != null && this.options.maxFiles > 0 && _i >= (this.options.maxFiles - 1)) {
                        break;
                    }
                }
                return _results;
            };
            this._addFilesFromItems = function(items) {
                var entry, item, _i, _len, _results;
                _results = [];
                for (_i = 0, _len = items.length; _i < _len; _i++) {
                    item = items[_i];
                    if ((item.webkitGetAsEntry != null) && (entry = item.webkitGetAsEntry())) {
                        if (entry.isFile) {
                            _results.push(this.addFile(item.getAsFile()));
                        } else if (entry.isDirectory) {
                            _results.push(this._addFilesFromDirectory(entry, entry.name));
                        } else {
                            _results.push(void 0);
                        }
                    } else if (item.getAsFile != null) {
                        if ((item.kind == null) || item.kind === "file") {
                            _results.push(this.addFile(item.getAsFile()));
                        } else {
                            _results.push(void 0);
                        }
                    } else {
                        _results.push(void 0);
                    }
                    // Make sure we don't handle more files than requested
                    if (this.options.maxFiles != null && this.options.maxFiles > 0 && _i >= (this.options.maxFiles - 1)) {
                        break;
                    }
                }
                return _results;
            };
        }
    };

Hope this helps ;)

I thought that the most intuitive single file upload process was to replace the previous file upon a new entry.

  $(".drop-image").dropzone({
    url: '/cart?upload-engraving=true',
    maxFiles: 1,
    maxfilesexceeded: function(file) {
        this.removeAllFiles();
        this.addFile(file);
    }
})

Dropzone.options.dpzSingleFile = {
    paramName: "file", // The name that will be used to transfer the file
    maxFiles: 1,
    init: function() {
        this.on("maxfilesexceeded", function(file) {
            this.removeAllFiles();
            this.addFile(file);
        });
    }
};

You can also add in callbacks - here I'm using Dropzone for Angular

dzCallbacks = {
    'addedfile' : function(file){
        $scope.btSend = false;
        $scope.form.logoFile = file;
    },
    'success' : function(file, xhr){
        $scope.btSend = true;
        console.log(file, xhr);
    },
    'maxfilesexceeded': function(file) {
         $timeout(function() { 
            file._removeLink.click();
        }, 2000);
    }
}

maxFiles: 1 does the job but if you also want to remove the additional files you can use this sample code taken from the Wiki page:

How can I limit the number of files?

You're in luck! Starting with 3.7.0 Dropzone supports the maxFiles option. Simply set it to the desired quantity and you're good to go. If you don't want the rejected files to be viewed, simply register for the maxfilesexceeded event, and remove the file immediately:

myDropzone.on("maxfilesexceeded", function(file)
{
    this.removeFile(file);
});

1. Set maxFiles Count: maxFiles: 1
2. In maxfilesexceeded event, clear all files and add a new file:

event: Called for each file that has been rejected because the number of files exceeds the maxFiles limit.

var myDropzone = new Dropzone("div#yourDropzoneID", { url: "/file/post", 
uploadMultiple: false, maxFiles: 1 });

myDropzone.on("maxfilesexceeded", function (file) {
    myDropzone.removeAllFiles();
    myDropzone.addFile(file);
});