Develop Reference

Write to file while stream downloading

How to write output of an octet-stream to a file while the stream is being downloaded ?
I receive the stream as a blob and then download it at the end of the stream, but how to receive the
stream and write to a file ?(something like a FileStream that takes a stream and writes to a file)
AJAX code below
$.ajax({
type: "post",
url: apiURL,
contentType: "application/json; charset=utf-8",
data: JSON.stringify(String(strCustomData)),
xhrFields: {
responseType: "blob", // <-- can also be an arrayBuffer
onprogress: function(e) { // <-- get response body here, read its stream and save in file
// TODO
}
},
cache: false,
headers: { "RequestVerificationToken": get_CSRF_TOKEN() },
success: function (response, textStatus, request) {
const requestHeaders = request.getResponseHeader("Content-Disposition") || "";
const requestContentType = request.getResponseHeader("Content-Type") || "application/zip";
const strFileName = requestHeaders?.split(";")[1]?.split("=")[1] || "File_Not_Found.zip";
const blob = response;
const url = window.URL || window.webkitURL;
const urlLink = url.createObjectURL(blob);
// create Anchor element that holds the blob and then download it as a file
const elementAnchor = document.createElement("a");
elementAnchor.setAttribute("href", urlLink);
elementAnchor.setAttribute("download", strFileName);
// download the file
elementAnchor.click();
// dispose blob object and delete it from memory
url.revokeObjectURL(urlLink);
elementAnchor.remove();
},
error: function (xhr, ajaxOptions, thrownError) {
// More validation code...
console.error(String(xhr.statusText));
}
});
I am looking for something like the anchor download tag <a asp-page-handler="apiURL" download>Download</a> where it receives a stream and downloads its without using a blob.
I would have used the anchor tag, but I need some Javascript code to be executed alongside it.(Progress bar, some required custom info to display, ...etc.)
I tried using StreamSaver.js but could not make it work in the onprogress section of the AJAX request.(how to get the response.body.getReader() in onprogress event ?how to save stream to a file without waiting for the download to complete ?)
Using JQuery inside Razor pages with Asp.Net Core.

Trying to POST multipart/form-data by javascript to web api

Here i have a form in which i have a input type file to upload my file when the upload button is click i need to post the multipart/form-data to web api
where i upload the file to Minio Server.I have pasted the javascript and web api i use below.
When i press upload button after i get 500 (Internal Server Error).Help me with suggestions.
$("#upload").click(function () {
var file = new FormData($('#uploadform')[0]);
file.append('tax_file', $('input[type=file]')[0].files[0]);
$.ajax({
type: "POST",
url: 'http://localhost:53094/api/values',
data: file,
//use contentType, processData for sure.
contentType: "multipart/form-data",
processData: false,
beforeSend: function () {},
success: function (msg) {
$(".modal .ajax_data").html("<pre>" + msg +
"</pre>");
$('#close').hide();
},
error: function () {
$(".modal .ajax_data").html(
"<pre>Sorry! Couldn't process your request.</pre>"
);
$('#done').hide();
}
});
});
[HttpPost]
public string Post(IFormFile file)
{
try
{
var stream = file.OpenReadStream();
var name = file.FileName;
minio.PutObjectAsync("student-maarklist", "sample.jpeg", stream, file.Length);
return "Success";
}
catch (Exception ex)
{
return ex.Message;
}
}

I think you need not mention localhost just the path to the file will do. or replace it with IP of the localhost.

Sorry i have dont a mistake the name i appended in javascript is not save as the name i gave in web api.
I changed,
file.append('tax_file', $('input[type=file]')[0].files[0]);
To
file.append('file', $('input[type=file]')[0].files[0]);
and it worked .

Javascript Blob to File / Sending Files through Ajax Request

In an Express app, I have a simple image uploader which was working perfectly using Ajax PUT requests. But now I need to crop the images before sending them to the server.
I plugged in Croppie to help with this. On form submit I get the cropped image blobs from Croppie, convert them to files, append the files to the Ajax FormData object, and send the FormData off to Express.
But the server isn't receiving and files, and examining the PUT request in Chrome's dev tools shows that no file info is being send.
I've console.logged the blobs and the files, and as far as I can tell they are being created properly.
Getting the blobs and converting them to files:
var fileList = []
if($croppieContainers.length > 0){
$.each($croppieContainers, function(i){
$(this).croppie('result', {
type: 'blob', // Get the blob from the croppie container
}).then(function(blob) {
let file = new File([blob], "image-" + i, {
type: blob.type,
lastModifiedDate: new Date(); // Make a file from the blob...
});
fileList.push(file) // And push it to fileList
});
});
}
Appending the files to ajaxData:
if(fileList.length > 0) {
$.each('fileList', function(file){
ajaxData.append($input.attr('name'), file);
})
}
posting to Express:
$.ajax({
url: $form.attr('action'),
type: $form.attr('method'),
data: ajaxData,
// dataType: 'json',
cache: false,
contentType: false,
processData: false,
complete: function() {
$form.removeClass('is-uploading');
},
success: function(data) {
// Handlers...
Console.log(blob) returns:
Blob
size:288345
type: "image/png"
__proto__: Blob
And the file:
File
lastModified : 1478972364233
lastModifiedDate : Sat Nov 12 2016 17:39:24 GMT+0000 (GMT)
name : "image-0"
size : 288345
type : "image/png"
webkitRelativePath : ""
__proto__ : File
I've tried getting the file a different way, but it gives the same result:
if($croppieContainers.length > 0){
$.each($croppieContainers, function(i){
let file = new File([$(this).croppie('result', {
type: 'blob'}
)],
"image-" + i)
ajaxData.append($input.attr('name'),file)
});
}
I'm note sure how to debug this, apart from console.logging at various stages, and checking the XHR in dev tools...
Can anyone see what the problem is, or tell me how I can debug further?
Thanks you!

File upload to the asp.net web service not working

I'm trying to upload file to the web service using JavaScript and JQuery. My current implementation is working correctly in the local environment.
But after deploying my solution to the server and try to access from outside it's not working and saying server side error occurred. Other thing I found is other web methods of the same web service are working correctly and just this file upload method is not working.
Here is my asp.net web service file upload method.
[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public object SaveFile()
{
var bugID = int.Parse(HttpContext.Current.Request.Form["bugID"]);
var fileName = HttpContext.Current.Request.Form["name"];
var fileType = HttpContext.Current.Request.Form["type"];
var file = HttpContext.Current.Request.Files[0];
// file saving logic
// .....
return new JavaScriptSerializer().Serialize(new
{
Message = 1,
Name = fileName,
DocumentID = attach.DocumentID // Saved file ID
});
}
Here is the javascript method I used to upload the file to the web service
function uploadFile() {
var data = new FormData(),
file = $("#fileToUpload")[0].files[0];
data.append("name", file.name);
data.append("size", file.size);
data.append("type", file.type);
data.append("file", file);
data.append("bugID", bugID);
$.ajax(
{
url: baseURL + "Webservice/BugsWebService.asmx/SaveFile",
dataType: "xml",
type: "POST",
data: data,
cache: false,
contentType: false,
processData: false,
success: function (res) {
console.log(res);
},
error: function (jqXHR, textStatus, errorThrown) {
console.log(jqXHR);
console.log(textStatus);
console.log(errorThrown);
}
});
}
In development environment web service url is
http://localhost:55225/Bugs/View.aspx
When host the site url is
http://[ip-address]/Internal/Bugs/View.aspx
This is the error I'm getting when try to upload the file
http://[ip-address]/Internal/Webservice/BugsWebService.asmx/SaveFile
500 (Internal Server Error)
What is the issue with my implementation?

Upload files to Dropbox using a Dropbox Core API in Javascript

I am working on a simple chrome-extension that needs to upload files to the user's dropbox folder. I am using the simple AJAX requests as mentioned below to upload files, however it works for files with extensions such as .txt, .json, .c, etc i.e. files whose mime type is of type text/plain or similar type but all other file types such as pdfs, image files etc get corrupted and produce blank contents. What am I missing in uploading the files the correct way.
function startUpload()
{
var folderPath = $(this).closest('tr').attr('path')+'/';
var file = $("#upload_file")[0].files[0];
if (!file){
alert ("No file selected to upload.");
return false;
}
var reader = new FileReader();
reader.readAsText(file, "UTF-8");
reader.onload = function (evt) {
uploadFile(folderPath+file.name,evt.target.result,file.size,file.type);
}
}
//function to upload file to folder
function uploadFile(filepath,data,contentLength,contentType){
var url = "https://api-content.dropbox.com/1/files_put/auto"+filepath;
var headers = {
Authorization: 'Bearer ' + getAccessToken(),
contentLength: contentLength,
};
var args = {
url: url,
headers: headers,
crossDomain: true,
crossOrigin: true,
type: 'PUT',
contentType: contentType,
data : data,
dataType: 'json',
success: function(data)
{
getMetadata(filepath.substring(0,filepath.lastIndexOf('/')),createFolderViews);
},
error: function(jqXHR)
{
console.log(jqXHR);
}
};
$.ajax(args);
}

I believe the issue is reader.readAsTextFile(file, "UTF-8"). If the file isn't a text file, this will misinterpret the contents. I think you want reader.readAsBinaryString or reader.readAsArrayBuffer. (I haven't tested it myself.)
EDIT
After testing this myself, I found that readAsArrayBuffer is what you need, but you also need to add processData: false as an option to $.ajax to prevent jQuery from trying to convert the data to fields in a form submission.
Also be sure to use dataType: 'json' to properly parse the response from the server.