How to retrieve file on server side send with ajax for a node/express app

Question

I have a Node/Express app and i want to sent a file with a form, i want to send it with ajax so i can process the server response.

So far my form is:

                    <form method='POST' enctype='multipart/form-data' id='excelform'>
                        <input type='file' id='target_file' name='target_file' required>
                    </form>
                    <button class='btn btn-menu3 align-self-end' onClick='excel_email9f();'>Enviar</button>

i have a button that calls the following function for an ajax request:

function excel_email9f(){

    var data = new FormData();
    var file = $('#target_file')[0].files[0];

    data.append('file', file);

    $.ajax({
        type: "POST",
        enctype: 'multipart/form-data',
        url: "/Excelemail9f",
        data: data,
        processData: false,
        contentType: false,
        cache: false,
        timeout: 600000,
        success: function (data) {

            var response = data.q0;
            alert(response);

        },
        error: function (e) {

            console.log("ERROR : ", e);

        }
    });

};

i can access the file and its properties like name.

On server side i have this route

app.post('/Excelemail9f',function(req,res){

    // checking req.files is empty or not
    if (Object.keys(req.files).length == 0) {
        return res.status(400).send('No files were uploaded.');
    }
    console.log('name: ' + req.files.target_file.name);
    let target_file = req.files.target_file;

    // target_file.mv(path, callback)
    target_file.mv(path.join(__dirname, 'uploads', target_file.name), (err) => {
        if (err) throw err;

        res.send(JSON.stringify({q0 : 0})); 
    })

})

How do i access the file on the server side, i use req.files.target_file but i get the following error:

TypeError: Cannot read property 'name' of undefined

Answer 1

You're post ing the data as a FormData object, but you're referring to the HTML input element's ID as the filename. You populate the FormData object by calling data.append('file', file); , so you need to reference it by req.files.file rather than req.files.target_file .