7

I was about to use XHR to send a file to the server when I realized that I don't have an end-point due to lack of routing.

Then I read this article and discovered I could potentially do file uploads by taking advantage of Meteor.methods. Now my upload looks something like this:

$(function() {
    $(document.body).html(Meteor.render(Template.files));
    $(document).on('drop', function(dropEvent) {
        _.each(dropEvent.originalEvent.dataTransfer.files, function(file) {
            var reader = new FileReader();
            reader.onload = function(fileLoadEvent) {
                Meteor.call('uploadFile', file, reader.result);
            };
            reader.readAsBinaryString(file);
        });
        dropEvent.preventDefault();
    });

    $(document).bind('dragover dragenter', function(e) {
        e.preventDefault();
    });

});

And in server/main.js I have this:

var require = __meteor_bootstrap__.require; // should I even be doing this? looks like an internal method
var fs = require('fs');
var path = require('path');

Meteor.methods({
    uploadFile: function(fileInfo, fileData) {
        var fn = path.join('.uploads',fileInfo.name);
        fs.writeFile(fn, fileData, 'binary', function(err) {
            if(err) {
                throw new Meteor.Error(500, 'Failed to save file.', err);
            } else {
                console.log('File saved to '+fn);
            }
        });
    }
});

Which just writes it to disk. This seems to work, but I don't know what technology Meteor is using to pass the data to that method on the server, and I don't know how to get progress info back.

Normally I'd attach an event listener to the xhr object, 

xhr.upload.addEventListener("progress", uploadProgress, false);

but I don't think I have access to one with .methods. Is there another way to do this?

4

1 回答 1

6

我也一直在研究这个，我有一些有效的代码。

首先澄清一下：

这似乎可行，但我不知道 Meteor 使用什么技术将数据传递给服务器上的该方法，我不知道如何取回进度信息。

Meteor 与服务器有一个WebSockets连接，并将其用作传输。因此，每次您调用Meteor.call或Meteor.apply时，它都会对您的参数（如果有）进行EJSON编码，调用服务器端的函数，并透明地返回响应。

这里的技巧是然后使用HTML5 的 FileReader Api以块的形式读取文件（这很重要，因为否则大文件会使您的浏览器崩溃）并为每个块执行 Meteor.call() 。

您的代码正在做两件对我来说效果不佳的事情：

  1. 它将文件作为二进制字符串读取：我发现使用 Base64 更可靠。您说您的代码已上传，但您是否检查过文件校验和以确保它们是同一个文件？
  2. 它一次读取文件。大文件（100 MB）会导致性能问题，根据我的经验，甚至会导致浏览器崩溃。

好的，现在回答你的问题。如何判断您上传了多少文件？您可以使您的块足够小，以便您可以使用 chunks_sent / total_chunks 作为指标。或者，您可以从 Meteor 服务器端调用中调用 Session.set( 'progress', current_size / total_size ) 并将其绑定到一个元素以便它更新。

这是我一直致力于包装此功能的 jQuery 插件。它不完整，但它会上传文件，它可能对您有所帮助。它目前只能通过拖放获取文件。没有“浏览”按钮。

免责声明：我对 Meteor & node 还很陌生，所以有些事情可能不会按照“推荐”的方式完成，但我会随着时间的推移对其进行改进并最终在 Github 中给它一个家。

;(function($) {

    $.uploadWidget = function(el, options) {

        var defaults = {
            propertyName: 'value',
            maximumFileSize: 1073741824, //1GB

            messageTarget: null
        };

        var plugin = this;

        plugin.settings = {}


        var init = function() {
            plugin.settings = $.extend({}, defaults, options);
            plugin.el = el;

            if( !$(el).attr('id') || !$(el).attr('id').length ){
                $(el).attr('id', 'uploadWidget_' + Math.round(Math.random()*1000000));
            }

            if( plugin.settings.messageTarget == null ){
                plugin.settings.messageTarget = plugin.el;
            }

            initializeDropArea();
        };


        // Returns a human-friendly string representation of bytes
        var getBytesAsPrettyString = function( bytes ){

            var sizes = ['Bytes', 'KB', 'MB', 'GB', 'TB'];
            if (bytes == 0) return 'n/a';
            var i = parseInt(Math.floor(Math.log(bytes) / Math.log(1024)));
            return Math.round(bytes / Math.pow(1024, i), 2) + ' ' + sizes[i];

        };


        // Throws an exception if the file (from a drop event) is unacceptable
        var assertFileIsAcceptable = function( file ){

            if( file.size > plugin.settings.maximumFileSize ){
                throw 'Files can\'t be larger than ' + getBytesAsPrettyString(plugin.settings.maximumFileSize);
            }

            //if( !file.name.match(/^.+?\.pdf$/i) ){
            //    throw 'Only pdf files can be uploaded.';
            // }

        };


        var setMainMessage = function( message ){

            $(plugin.settings.messageTarget).text( message );

        };


        plugin.getUploader = function(){

            return plugin.uploader;

        };


        var initializeDropArea = function(){

            var $el = $(plugin.el);

            $.event.props.push("dataTransfer");

            $el.bind( 'dragenter dragover dragexit', function(){
                event.stopPropagation();
                event.preventDefault();
            });

            $el.bind( 'drop', function( event ){

                var slices;
                var total_slices;

                var processChunkUpload = function( blob, index, start, end ){

                    var chunk;

                    if (blob.webkitSlice) {
                        chunk = blob.webkitSlice(start, end);
                    } else if (blob.mozSlice) {
                        chunk = blob.mozSlice(start, end);
                    } else {
                        chunk = blob.slice(start,end);
                    }

                    var reader = new FileReader();

                    reader.onload = function(event){

                        var base64_chunk = event.target.result.split(',')[1];

                        slices--;

                        $el.text( slices + ' out of ' + total_slices + ' left' );

                        Meteor.apply(
                            'saveUploadFileChunk',
                            [file_name, base64_chunk, slices+1],
                            { wait: true }
                        );
                    };

                    reader.readAsDataURL(chunk);
                };


                event.stopPropagation();
                event.preventDefault();
                event.dataTransfer.dropEffect = 'copy';

                if( !event.dataTransfer.files.length ){
                    return;
                }

                const BYTES_PER_CHUNK = 1024 * 1024; // 1MB chunk sizes.


                var blob = event.dataTransfer.files[0];
                var file_name = blob.name;

                var start = 0;
                var end;
                var index = 0;

                // calculate the number of slices we will need
                slices = Math.ceil(blob.size / BYTES_PER_CHUNK);
                total_slices = slices;

                while(start < blob.size) {
                    end = start + BYTES_PER_CHUNK;
                    if(end > blob.size) {
                        end = blob.size;
                    }

                    processChunkUpload( blob, index, start, end );

                    start = end;
                    index++;
                }


            });

        };

        init();

    }

})(jQuery);

这是我的流星发布方法。

Meteor.methods({

        // this is TOTALLY insecure. For demo purposes only.
        // please note that it will append to an existing file if you upload a file by the same name..
        saveUploadFileChunk: function ( file_name, chunk, chunk_num ) {

                var require = __meteor_bootstrap__.require;
                var fs = require('fs');
                var crypto = require('crypto')

                var shasum = crypto.createHash('sha256');
                shasum.update( file_name );

                var write_file_name = shasum.digest('hex');

                var target_file = '../tmp/' + write_file_name;

                fs.appendFile(
                        target_file,
                        new Buffer(chunk, 'base64'),
                        {
                                encoding: 'base64',
                                mode: 438,
                                flag: 'a'
                        }
                        ,function( err ){

                                if( err ){

                                        console.log('error ' + err);
                                }

                                console.log( 'wrote ' + chunk_num );

                        }
                );

                return write_file_name;

        }
});

高温高压

于 2013-03-22T19:10:14.120 回答