Upload multiple files to Amazon S3 using plupload

Question

I'm using plupload to upload images to Amazon S3. I have a method on the server which generates my signature and policy, which I call through Http GET.

This works just fine for uploading one filet at a time.

The problem is when I select multiple files to upload. I need to call my server method GetPolicy before each file upload, but the problem is that the upload sometime starts before I get the Response from GetPolicy. Here's a bit of code:

uploader.bind("FileFiltered", function (up, file) {
    getAmazonUploadPolicty(function (response) {
        uploader.settings.multipart_params.key = "test/" + response.FileId;
        uploader.settings.multipart_params.policy = response.policy;
        uploader.settings.multipart_params.signature = response.Signature;
        uploader.settings.multipart_params.Filename = response.FileId;
    });
});

uploader.bind("FilesAdded", function (up, files) {
    setTimeout(function () {
        uploader.start();
    }, 200);
});

What I would need is to be able to trigger the upload programatically for a specific file in the call back of the getAmazonUploadPolicty method.

Any ideas? Thanks

Answer 1

Found a solution.

I've created a method Get policies for several files - as many as the user has selected

getAmazonUploadPolicyItems(count, callback); 

The server method returns a list of policies

And then I do this

var pocilites = { };

uploader.bind("BeforeUpload", function (up, file) {
    // this fires before each file upload

    var response = policies[file.id];
    uploader.settings.multipart_params.key = response.key;
    uploader.settings.multipart_params.policy = response.policy;
    uploader.settings.multipart_params.signature = response.signature;
    uploader.settings.multipart_params.Filename = response.filename;        
});

uploader.bind("FilesAdded", function (up, files) {
    getAmazonUploadPolicyItems(files.length, function (response) {

        $.each(files, function(i, file) {
            policies[file.id] = {
                key: response[i].Key,
                policy: response[i].Policy,
                signature: response[i].Signature,
                filename: response[i].Filename 
            };
        });

        uploader.start();
    });
});

Hope this helps someone esle.

PS: For some unknown reason, sometimes when uploading several files I get "invalid signature" from Amazon, but on a second attempt it works fine. Any ideas?

Answer 2

Sounds tricky.... I think you would be better off tossing the uploader.start into the FileFiltered command though in your amazon callback that way you're sure you get a response back and you can verify it's what you're after before you even try starting the upload.

uploader.bind("FileFiltered", function (up, file) {
    getAmazonUploadPolicty(function (response) {
        uploader.settings.multipart_params.key = "test/" + response.FileId;
        uploader.settings.multipart_params.policy = response.policy;
        uploader.settings.multipart_params.signature = response.Signature;
        uploader.settings.multipart_params.Filename = response.FileId;
        uploader.start();
    });
});

This still doesn't solve the problem of your multi-file issue. I'm not aware of anything in plupload that allows you to just upload a specific file (though it sure would be nice) since the uploads are all managed as a queue when it comes time to upload. Theoretically maybe you could do something to create a new queue for each file? seems kinda odd there's nothing exposed to start an upload for a specific file