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

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

You can use Flask-WTF to handle file uploads by creating a custom form with a FileField. Would you like a code example?

Yes, please provide a code example for a file upload form.

Here's a simple example:

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

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

class UploadForm(FlaskForm):
    file = FileField('File', validators=[DataRequired()])
    submit = SubmitField('Upload')

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

if __name__ == '__main__':
    app.run(debug=True)

This code sets up a basic file upload form.

How do I handle file validation and size limits?

You can add custom validators to check the file type and size. For example, you can create a function to validate the file extension and size before processing it.