Upload File Component with ReactJS

I worked on this quite a while as well. This what I came up with.

A Dropzone component, coupled with using superagent.

// based on https://github.com/paramaggarwal/react-dropzone, adds image preview    
const React = require('react');
const _ = require('lodash');

var Dropzone = React.createClass({
  getInitialState: function() {
    return {
      isDragActive: false
    }
  },

  propTypes: {
    onDrop: React.PropTypes.func.isRequired,
    size: React.PropTypes.number,
    style: React.PropTypes.object
  },

  onDragLeave: function(e) {
    this.setState({
      isDragActive: false
    });
  },

  onDragOver: function(e) {
    e.preventDefault();
    e.dataTransfer.dropEffect = 'copy';

    this.setState({
      isDragActive: true
    });
  },

  onDrop: function(e) {
    e.preventDefault();

    this.setState({
      isDragActive: false
    });

    var files;
    if (e.dataTransfer) {
      files = e.dataTransfer.files;
    } else if (e.target) {
      files = e.target.files;
    }

    _.each(files, this._createPreview);
  },

  onClick: function () {
    this.refs.fileInput.getDOMNode().click();
  },

  _createPreview: function(file){
    var self = this
      , newFile
      , reader = new FileReader();

    reader.onloadend = function(e){
      newFile = {file:file, imageUrl:e.target.result};
      if (self.props.onDrop) {
        self.props.onDrop(newFile);
      }
    };

    reader.readAsDataURL(file);
  },

  render: function() {

    var className = 'dropzone';
    if (this.state.isDragActive) {
      className += ' active';
    };

    var style = {
      width: this.props.size || 100,
      height: this.props.size || 100,
      borderStyle: this.state.isDragActive ? 'solid' : 'dashed'
    };

    return (
      <div className={className} onClick={this.onClick} onDragLeave={this.onDragLeave} onDragOver={this.onDragOver} onDrop={this.onDrop}>
        <input style={{display: 'none' }} type='file' multiple ref='fileInput' onChange={this.onDrop} />
        {this.props.children}
      </div>
    );
  }

});

module.exports = Dropzone

Using the Dropzone.

    <Dropzone onDrop={this.onAddFile}>
      <p>Drag &amp; drop files here or click here to browse for files.</p>
    </Dropzone>

When a file is added to the drop zone, add it to your list of files to upload. I add it to my flux store.

  onAddFile: function(res){
    var newFile = {
      id:uuid(),
      name:res.file.name,
      size: res.file.size,
      altText:'',
      caption: '',
      file:res.file,
      url:res.imageUrl
    };
    this.executeAction(newImageAction, newFile);
  }

You can use the imageUrl to display a preview of the file.

  <img ref="img" src={this.state.imageUrl} width="120" height="120"/>

To upload the files, get the list of files and send them through superagent. I'm using flux, so I get the list of images from that store.

  request = require('superagent-bluebird-promise')
  Promise = require('bluebird')

    upload: function(){
      var images = this.getStore(ProductsStore).getNewImages();
      var csrf = this.getStore(ApplicationStore).token;
      var url = '/images/upload';
      var requests = [];
      var promise;
      var self = this;
      _.each(images, function(img){

        if(!img.name || img.name.length == 0) return;

        promise = request
          .post(url)
          .field('name', img.name)
          .field('altText', img.altText)
          .field('caption', img.caption)
          .field('size', img.size)
          .attach('image', img.file, img.file.name)
          .set('Accept', 'application/json')
          .set('x-csrf-token', csrf)
          .on('progress', function(e) {
            console.log('Percentage done: ', e.percent);
          })
          .promise()
          .then(function(res){
            var newImg = res.body.result;
            newImg.id = img.id;
            self.executeAction(savedNewImageAction, newImg);
          })
          .catch(function(err){
            self.executeAction(savedNewImageErrorAction, err.res.body.errors);
          });
        requests.push(promise);
      });

      Promise
        .all(requests)
        .then(function(){
          console.log('all done');
        })
        .catch(function(){
          console.log('done with errors');
        });
    }