Part 6: Building a User-Friendly Todo App with Flask - Step-by-Step Guide to Delete Todo and Category Items via DELETE Requests

Hey everyone, welcome to the sixth part of my Flask-based basic todo application series. In this post, I'll guide you through how you can delete your todo and category items via DELETE requests in your Flask todo app. Let's dive in!.

For Todo Items:

to begin copy the code bellow and use it to replace the deleteTodo function 

function deleteTodo(todoId) {
    // Perform a DELETE request to the specified todo ID
    fetch(`/todos/${todoId}`, {
        method: "DELETE", // Using the DELETE method
    })
    .then(response => {
        // Check if the response is successful (status code 200-299)
        if (response.ok) {
            console.log(`Todo with ID ${todoId} deleted`); // Log success message
            window.location.replace("http://127.0.0.1:5000"); // Redirect to home page after deletion
            // Optionally, you can remove the deleted todo from the UI here
        } else {
            console.error('Error deleting todo', response.statusText); // Log error if deletion fails
        }
    })
    .catch(error => {
        console.error('Error:', error); // Catch and log any errors during the API request
    });
}

 

This JavaScript function is triggered whenever the user clicks on the delete (trash) icon and sends a DELETE request to delete a todo item with the specified ID. Upon success, it logs a success message, redirects to the home page, and optionally removes the deleted todo from the user interface. If there's an error during the deletion process, it logs an error message

Now in your app.py file lets create our delete todo endpoint by adding in the codes below

@app.route('/todos/<id>', methods=['DELETE'])
def delete_todo(id):
    try:
        # Fetch the todo with the specified ID from the database
        todo = Todo.query.get(id)
        if not todo:
            return jsonify({'error': 'Todo not found'}), 404  # Return a 404 error if todo not found
        
        # Delete the fetched todo from the database
        db.session.delete(todo)
        
        # Commit the changes to the database
        db.session.commit()
        
        # Flash a success message to indicate successful deletion
        flash("Todo was deleted successfully")
        
        # Return a success message with status code 204 (No Content)
        return jsonify({'message': 'Success!'}), 204
    
    except Exception as e:
        db.session.close()  # Close the session in case of an exception
        # Optionally, abort with a 404 error code or handle the exception as needed
        # abort(404)

This Python code defines a route that listens for DELETE requests to delete a todo item based on its ID. It fetches the todo item from the database using the provided ID, deletes it from the database, commits the changes, flashes a success message, and returns a success message with a status code of 204 if successful. If there's an exception during this process, it closes the session or optionally handles the exception by aborting with a 404 error code.

Refresh your page, click the delete icon of any todo item, and see it removed from the todo list.

Thats all for deleting todo items, refresh your page and click on the delete icon (trash icon) of any todo item and you will see that the item is removed from the todo list.

For Deleting Categories:

 

to begin copy the code bellow and use it to replace the deleteCategory function 

function deleteCategory(categoryId) {
    // Send a DELETE request to the specified category ID route
    fetch(`/categories/${categoryId}`, {
        method: "DELETE", // Using the DELETE HTTP method
    })
    .then(response => {
        if (response.ok) {
            // Log success message if the deletion is successful
            console.log(`Category with ID ${categoryId} deleted`);
            
            // Redirect to the home page after successful deletion
            window.location.replace("http://127.0.0.1:5000");
            // Optionally, remove the deleted category from the UI here
        } else {
            // Log an error if deletion fails
            console.error('Error deleting category', response.statusText);
        }
    })
    .catch(error => {
        // Log any errors that occur during the request
        console.error('Error:', error);
    });
}

This JavaScript function performs a DELETE request to a specific category ID endpoint. If the response status is successful (status code 200-299), it logs a success message, redirects the user to the home page (http://127.0.0.1:5000), and optionally removes the deleted category from the user interface. If the deletion fails or encounters an error, it logs an error message.

Now in your app.py file lets create our delete todo endpoint by adding in the codes below

@app.route('/categories/<int:id>', methods=['DELETE'])
def delete_category(id):
    try:
        # Retrieve the category using the provided ID from the URL
        category = Category.query.get(id)
        
        # Check if the category exists
        if category:
            # Delete the category from the database
            db.session.delete(category)
            db.session.commit()
            
            # Return a success message and status code 204 (no content)
            return jsonify({'message': 'Category deleted successfully'}), 204
        else:
            # If category does not exist, return a 404 error
            return jsonify({'error': 'Category not found'}), 404
    except Exception as e:
        # Rollback changes if any exception occurs
        db.session.rollback()
        
        # Return an error message and status code 500 (server error)
        return jsonify({'error': str(e)}), 500

The above route handles HTTP DELETE requests to a specific category ID endpoint (/categories/<int:id>). It attempts to delete the category corresponding to the provided ID from the database. If the category exists, it gets deleted, and a success message with a status code 204 (no content) is returned. If the category does not exist, it returns a 404 error. If an exception occurs during the deletion process, it rolls back any changes made and returns a server error (status code 500) along with the error details.

Refresh your page, click the delete icon of any category item, and see it removed from the category list.

That wraps up this part of the series. Check out the video below for a step-by-step guide. Feel free to ask any questions or leave comments below. Thanks for reading, and until next time!