Uploading both data and files in one form using Ajax?

javascript

ajax

form-data

file-upload

byAlex Kataev·Nov 7, 2024

To upload data and files in one form with Ajax, utilize the FormData object. This paving stone of web development allows you to attach both text fields and files to it, then send using fetch:

let formData = new FormData();
formData.append('textData', 'Inevitable iron-man quote here'); // Attach text data
formData.append('file', document.querySelector('input[type="file"]').files[0]); // Attach the "Avenge the fallen" .mp3 file

fetch('/upload', {
  method: 'POST',
  body: formData
})
.then(response => response.json()) // Handle success like Tony stark.
.catch(error => console.error('Hulk smash!', error)); // Handle error

No need for setting Content-Type headers—FormData behaves like Jarvis, doing that for you. On the server side, data is accessible like a standard form submission.

A snapshot of potential pitfalls and pointers when using FormData

Ensuring MVC flow To ensure seamless integration with the MVC pattern, remember to match your input names with your model properties. Like matching the infinity stones to their matching gauntlet hole.

The beauty of Ajax options

In the jQuery $.ajax(), setting contentType: false and processData: false allows the form data to maintain the multipart form-data encoding, helping the server handle the files as standard form submissions.

$.ajax({
    url: '/upload',
    type: 'POST',
    data: formData,
    contentType: false,   // Don't content type me, or my son, ever again.
    processData: false,    // If (false) return; 🤣.
    success: function(response) { ... },
    error: function(/* Life, Universe, Everything */ xhr, status, error) { ... }
});

Transparency in File Progress

For an interactive user experience during the upload process, xhr event listeners in Ajax allow you to monitor upload progress or provide user feedback.

Exploring the Companionship of FormData and Fetch API

Fetch API embraces FormData directly, offering a cleaner, streamlined approach that is in line with modern JavaScript practices. So, you can bid farewell to jQuery, if you want to.

iframe Cons

While iframes can handle file uploads, the limited debug capabilities and no progress tracking keep them behind the curtains. Fetch then comes forward as a more transparent means to upload files and data in unison.

Alternative Techniques and Important Considerations

Embrace the Future with Axios

Consider using Axios, the popular, promising HTTP client, bringing in features like request cancellation, and friendly with modern async/await patterns in JavaScript.

Validation: An Ounce of Prevention is Worth a Pound of Cure

Validate your form data on the client side, preventing unnecessary server requests and enhancing the user experience. Keep checks on parameters like file size and type to reduce the load of back and forth server requests.

MVC Alignment

For MVC devs, make sure your input names align with your model properties. This consistency ensures correct server-side binding of file uploads and text data, streamlining the data handling process.

explain-codes / Javascript / Uploading both data and files in one form using Ajax?

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