Dropzone and Upload Sessions

Yolo

 

Im using Dropzone.js to upload files to our server in the first instance. 

In the secon Im streaming the file straight to a Dreopbox App folder. These files could be as big as 5-6GB so Im using the upload_session route. 

 

Dropzone doesnt particularly allow for changing the headers and url between chunks but Ive managed to conditionally identify the first, middle and last chunks. 

 

My issue is that I keep getting the same error:

upload_session/append_v2 409 (incorrect_offset/)

 

 

Apologies for lengthy code. This is just a quick HTML doc with some JS. 

jQuery('div#dropzone').dropzone({

	//Dynamic URL
	url: 'https://content.dropboxapi.com/2/files/upload_session/start',
	method: 'POST',
	withCredentials: false,

	//Set headers for the request
	headers: {
		'Authorization' : 'Bearer <REDACTED>',
		'Content-Type' : 'application/octet-stream',
		'Dropbox-API-Arg' : JSON.stringify({close:false}),					
		'Cache-Control': null,
		'X-Requested-With': null,
		'Access-Control-Allow-Headers': null
	},
	
	//Chunking options
	chunking: true,
	forceChunking: true,
	chunkSize: 2500000, /* Testing with a 5MB File */
	retryChunks: true,
	retryChunksLimit: 3,
	
	//Handle chunks and endpoints
	params: function(file, xhr, chunk){},

	//Processing the que
	init: function(){	

		dropzone = this;

		this.on('uploadprogress', function(file, progress, bytesSent){

			var chunks = file.upload.chunks

				/**
				 * WHen there is only 1 chunk, save the response as the session ID
				 * Then update the URL and add the offset for /append_v2
				 */
				if (chunks.length == 1) {

                                        //Function to get the session ID from response
                                        sessionid = knpv_get_sessionid(file);								

					if (sessionid) {									
					
						//Headers
						dropzone.options.url = 'https://content.dropboxapi.com/2/files/upload_session/append_v2';							
						dropzone.options.headers['Dropbox-API-Arg'] = JSON.stringify({
							'cursor': {
								'session_id': sessionid,
								'offset': file.upload.bytesSent
							},
							'close':false
						});		

					}	
								
				}				

		});

		//When sending the chunk, update the URL and prams
		this.on('sending', function(file, xhr, formData){

			var chunks = file.upload.chunks;

			/**
			 * All the middle chunks
			 */
			if (chunks.length > 1 && chunks.length < file.upload.totalChunkCount) {
				/**
				 * Set headers
				 * 		sessionID
				 * 		offset
				 */
				dropzone.options.headers['Dropbox-API-Arg'] = JSON.stringify({
					'cursor': {
						'session_id': sessionid,
						'offset': file.upload.bytesSent
					},
					'close': false
				});								
			}

			/**
			 * The final chunk
			 */
			if (chunks.length > 1 && chunks.length == file.upload.totalChunkCount) {
				/**
				 * Set headers
				 * 		sessonID
				 * 		offset
				 * 		commit						
				 */
				dropzone.options.url = 'https://content.dropboxapi.com/2/files/upload_session/finish';
				dropzone.options.headers['Dropbox-API-Arg'] = JSON.stringify({
					'cursor': {
						'session_id': sessionid,
						'offset': file.upload.bytesSent
					},
					'commit': {
						'path': path+'/'+file.name,
						'mode': 'overwrite'
					}
				});
			}
		
		});

	}
});