How can I implement asynchronous file uploads in Flask using WTForms?

How can I implement asynchronous file uploads in Flask using WTForms?

You can use Flask-WTF along with JavaScript's Fetch API to handle asynchronous file uploads. First, ensure you have Flask-WTF installed.

What do I need to set up in my Flask app?

You'll need to create a form class using Flask-WTF, define a file field, and set up a route to handle the file upload.

Can you show me a code example?

Sure! Here's a simple example:

from flask import Flask, request, render_template
from flask_wtf import FlaskForm
from wtforms import FileField, SubmitField

app = Flask(__name__)
app.secret_key = 'your_secret_key'

class UploadForm(FlaskForm):
    file = FileField('Upload File')
    submit = SubmitField('Submit')

@app.route('/', methods=['GET', 'POST'])
def upload():
    form = UploadForm()
    if form.validate_on_submit():
        file = form.file.data
        # Process the file here
        return 'File uploaded successfully!'
    return render_template('upload.html', form=form)

Make sure to handle the file processing asynchronously!

What about the front-end part?

On the front end, you can use JavaScript to send the file using the Fetch API. Here's a simple example:

const form = document.getElementById('uploadForm');
form.addEventListener('submit', async (e) => {
    e.preventDefault();
    const formData = new FormData(form);
    const response = await fetch('/', {
        method: 'POST',
        body: formData,
    });
    const result = await response.text();
    alert(result);
});