Send FormData and string using one function

Question

I want to send data from the form (file from input and string from input) using ajax to ASP.NET Function. If I send only files i use:

function readURL() {
 var input = document.getElementById("fileUpload");
 var files = input.files;
 var formData = new FormData();
 var test = "some text";
 for (var i = 0; i != files.length; i++) {
   formData.append("files", files[i]);
  }
 $.ajax({
  type: "POST",
  url: '/Apartment/UploadFiles',
  data: {files: formData },
  processData: false,
  contentType: false,
 });
}

If I want to send an only string, I use:

function readURL() {
 var input = document.getElementById("fileUpload");
 var files = input.files;
 var formData = new FormData();
 var test = "some text";
 for (var i = 0; i != files.length; i++) {
   formData.append("files", files[i]);
  }
 $.ajax({
  type: "POST",
  url: '/Apartment/UploadFiles',
  data: { test: test},
  dataType: "json",
 });
}

It is possible to send string and FormData using one Ajax? I try something like this:

$.ajax({
 type: "POST",
 url: '/Apartment/UploadFiles',
 data: {files: formData, test: test },
 processData: false,
 contentType: false,
});

but now the string parameter is not sending (is null).

Additional - My Controller code

public async Task<IActionResult> UploadFiles(string test, IList<IFormFile> files)
        {
            ...
        }

is test an actual variable with a string value or did you miss the quotes ? You can add values to formData Object with formData.append(name, value); — Lapskaus
– Lapskaus, Commented Nov 4, 2020 at 13:51
in code for test it i create string variable in function where is located AJAX var test = "some txt"; — Adam
– Adam, Commented Nov 4, 2020 at 13:52
try to append your string to the formdata object as mentioned above — Lapskaus
– Lapskaus, Commented Nov 4, 2020 at 13:54
i try use formData.append(test, value) but now it doesn't work (file is not sending). I think that NAME parameter (formData.append(NAME, value) must be this same name who i using in ASP.Function public async Task<IActionResult> UploadFiles(IList<IFormFile> NAME). In other case this doesn't work — Adam
– Adam, Commented Nov 4, 2020 at 14:05
Appending a value to your formData Object will not work in that case . I am not familiar with ASP, that being said, i guess you would have to create a new dto that includes the string and your IFormFile and use that dto in your UploadFiles function as a parameter. Then you can access the string and the file withing that dto in your function — Lapskaus
– Lapskaus, Commented Nov 4, 2020 at 14:20

Emiel Zuurbier · Accepted Answer · 2020-11-04 14:24:53Z

2

It's not possible to combine multiple Content Types when sending a FormData object.

Append the string to the formData instance and set the name to test.

function readURL() {
  var input = document.getElementById("fileUpload");
  var files = input.files;
  var formData = new FormData();
  var test = "some text";

  for (var i = 0; i != files.length; i++) {
    formData.append("files", files[i]);
  }

  formData.append("test", test);

  $.ajax({
    type: "POST",
    url: '/Apartment/UploadFiles',
    data: formData,
    dataType: "json",
    processData: false,
    contentType: false,
  });
}

answered Nov 4, 2020 at 14:24

Emiel Zuurbier

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1 Comment

Adam Over a year ago

Omg you are soo clever, I would never thought of that! Thanks :)

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