What are the best practices for file uploads using WTForms?

What are the best practices for file uploads using WTForms?

When using WTForms for file uploads, it's important to validate file types, limit file sizes, and provide user feedback.

How can I validate the file type in WTForms?

You can use the FileField with a custom validator to check the file extension or MIME type.

What is a good way to limit the file size?

You can set a maximum file size in your form's validation logic, and also check it on the server side.

Can you give an example of a custom validator?

Sure! You can create a custom validator like this: def validate_file(form, field): if field.data.size > MAX_SIZE: raise ValidationError('File is too large.').