Can I append an array to 'formdata' in javascript?

I'm using FormData to upload files. I also want to send an array of other data.

When I send just the image, it works fine. When I append some text to the formdata, it works fine. When I try to attach the 'tags' array below, everything else works fine but no array is sent.

Any known issues with FormData and appending arrays?

Instantiate formData:

formdata = new FormData();

The array I create. Console.log shows everything working fine.

        // Get the tags
		tags = new Array();
		$('.tag-form').each(function(i){
			article = $(this).find('input[name="article"]').val();
			gender = $(this).find('input[name="gender"]').val();
			brand = $(this).find('input[name="brand"]').val();
			this_tag = new Array();
			this_tag.article = article;
			this_tag.gender = gender;
			this_tag.brand = brand;
			tags.push(this_tag);	
			console.log('This is tags array: ');
			console.log(tags);
		});
		formdata.append('tags', tags);
		console.log('This is formdata: ');
		console.log(formdata);

How I send it:

		// Send to server
		$.ajax({
			url: "../../build/ajaxes/upload-photo.php",
			type: "POST",
			data: formdata,
			processData: false,
			contentType: false,
			success: function (response) {
				console.log(response);
				$.fancybox.close();
			}
		});

How about this?

formdata.append('tags', JSON.stringify(tags));

... and, correspondingly, using json_decode on server to deparse it. See, the second value of FormData.append can be...

> a Blob, File, or a string, if neither, the value is converted to a > string

The way I see it, your tags array contains objects (@Musa is right, btw; making this_tag an Array, then assigning string properties to it makes no sense; use plain object instead), so native conversion (with toString()) won't be enough. JSON'ing should get the info through, though.

As a sidenote, I'd rewrite the property assigning block just into this:

tags.push({article: article, gender: gender, brand: brand});

Writing as

var formData = new FormData;
var array = ['1', '2'];
for (var i = 0; i < array.length; i++) {
    formData.append('array_php_side[]', array[i]);
}

you can receive just as normal array post/get by php.

use "xxx[]" as name of the field in formdata (you will get an array of - stringified objects - in you case)

so within your loop

$('.tag-form').each(function(i){
            article = $(this).find('input[name="article"]').val();
            gender = $(this).find('input[name="gender"]').val();
            brand = $(this).find('input[name="brand"]').val();
            this_tag = new Array();
            this_tag.article = article;
            this_tag.gender = gender;
            this_tag.brand = brand;
            //tags.push(this_tag);    
            formdata.append('tags[]', this_tag);
...
 

We can simply do like this.

formData = new FormData;
words = ["apple", "ball", "cat"]
words.forEach((item) => formData.append("words[]", item))

// verify the data
console.log(formData.getAll("words[]"))
//["apple", "ball", "cat"]

On server-side you will get words = ["apple", "ball", "cat"]

Function:

function appendArray(form_data, values, name){
	if(!values && name)
		form_data.append(name, '');
	else{
		if(typeof values == 'object'){
			for(key in values){
				if(typeof values[key] == 'object')
					appendArray(form_data, values[key], name + '[' + key + ']');
				else
					form_data.append(name + '[' + key + ']', values[key]);
			}
		}else
			form_data.append(name, values);
	}

	return form_data;
}

Use:

var form = document.createElement('form');// or document.getElementById('my_form_id');
var formdata = new FormData(form);

appendArray(formdata, {
	sefgusyg: {
		sujyfgsujyfsg: 'srkisgfisfsgsrg',
    },
    test1: 5,
    test2: 6,
    test3: 8,
    test4: 3,
    test5: [
	    'sejyfgjy',
        'isdyfgusygf',
    ],
});

Simply you can do like this:

var formData = new FormData();
formData.append('array[key1]', this.array.key1);
formData.append('array[key2]', this.array.key2);

var formData = new FormData;
var alphaArray = ['A', 'B', 'C','D','E'];
for (var i = 0; i < alphaArray.length; i++) {
    formData.append('listOfAlphabet', alphaArray [i]);
}

And In your request you will get array of alphabets.

var formData = new FormData; var arr = ['item1', 'item2', 'item3'];

arr.forEach(item => {
    formData.append(
        "myFile",item
    ); });

This is the way I did it:

const data = new FormData();
data.append('id', class.id);
data.append('name', class.name);

class.people.forEach((person, index) => {
    data.append(`people[${index}].id`, person.id);
    data.append(`people[${index}].firstname`, person.firstname);
    data.append(`people[${index}].lastname`, person.lastname);

    // Append images
    person.images.forEach((image, imageIndex) =>
        data.append(`people[${index}].images`, {
            name: 'image' + imageIndex,
            type: 'image/jpeg',
            uri: image,
        })
    );
});

I am using React on the frontend and Asp.Net on the backend.

You can only stringify the array and append it. Sends the array as an actual Array even if it has only one item.

const array = [ 1, 2 ];
let formData = new FormData();
formData.append("numbers", JSON.stringify(array));

This works for me when I sent file + text + array:

const uploadData = new FormData();
if (isArray(value)) {
  const k = `${key}[]`;
  uploadData.append(k, value);
} else {
  uploadData.append(key, value);
}


const headers = {
  'Content-Type': 'multipart/form-data',
};

I'm sending files(array) using formData in vuejs
for me below code is working

        if(this.requiredDocumentForUploads.length > 0) {
            this.requiredDocumentForUploads.forEach(file => {
                var name = file.attachment_type  // attachment_type is using for naming
                if(document.querySelector("[name=" + name + "]").files.length > 0) {
                    formData.append("requiredDocumentForUploadsNew[" + name + "]", document.querySelector("[name=" + name + "]").files[0])
                }
            })
        }

Use JSON.stringify at the frontend as below:

...
...
const entityData = new FormData();
entityData.append("Entities Open", JSON.stringify(login_entities));
axios
.post("/oneview/load_entity", entityData)
.then(response => {
   var entity_group = response.data.entity_group;
   var entity_code = response.data.entity_code;
   var entity_name = response.data.entity_name;
})
.catch(error => {
   console.log(error);
   alert(error);
});

Then use json.loads() at the backend as below:

...
...
login_entities = json.loads(request.POST.get('Entities Open'))
for i in login_entities:
   ...
   ...