Document Upload Form

Build a Flask web form for uploading documents to a content management system. The form should validate uploaded files to ensure only specific document types are accepted.

Requirements

Form Validation

The upload form must accept the following document types:

• PDF documents (.pdf)
• Microsoft Word documents (.doc, .docx)
• Text files (.txt)

Files with other extensions should be rejected with an appropriate error message.

Form Structure

Create a Flask form class with:

• A file upload field that accepts a single document
• A submit button

The form should provide clear feedback when validation fails.

Web Application

Implement a Flask application with:

• A route that displays the upload form (GET request)
• A route that processes form submissions (POST request)
• When validation succeeds, display the uploaded filename
• When validation fails, re-display the form with error messages

Test Cases

• Uploading a PDF file with extension .pdf succeeds @test
• Uploading a Word document with extension .docx succeeds @test
• Uploading a text file with extension .txt succeeds @test
• Uploading an image file with extension .jpg fails with validation error @test
• Uploading a file with extension .PDF (uppercase) succeeds @test

Implementation

@generates

API

from flask import Flask, render_template_string, request
from flask_wtf import FlaskForm

app = Flask(__name__)
app.config['SECRET_KEY'] = 'test-secret-key'

class DocumentUploadForm(FlaskForm):
    """Form for uploading documents with extension validation."""
    pass

@app.route('/', methods=['GET', 'POST'])
def upload():
    """Handle document upload form display and submission."""
    pass

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

Dependencies { .dependencies }

Flask { .dependency }

Provides the web framework for handling routes and requests.

Flask-WTF { .dependency }

Provides form handling and validation capabilities for Flask applications.