Notificaciones con Flash Messages

Flash messages are an essential tool in modern web development to provide instant feedback to users. When we implement this functionality in our applications, we significantly improve the user experience by confirming actions such as creation or deletion of items. Let's see how to implement these messages in a Flask application and how they can transform the interaction with our users.

What are Flash Messages and why are they important?

Flash Messages are temporary messages that are displayed to the user after performing a specific action. These messages travel betweenrequests across sessions, allowing you to display relevant information about completed actions or errors that have occurred.

Main characteristics:

• They persist between requests for the same user.
• They are stored in encrypted cookies
• Disappear after being displayed once
• They can be categorized (success, error, warning).

The importance of these messages is that they provide immediate feedback to the user, improving the usability of the application and reducing confusion about whether an action was completed correctly.

How to implement Flash Messages in a Flask application?

The implementation of flash messages in Flask is relatively simple thanks to the fact that this functionality is built into the framework. Let's take a step-by-step look at how to do it:

Initial configuration

First, we need to configure a secret key to encrypt the cookies that will carry our messages:

# Configuring the secret key to encrypt cookiesapp.secret_key = "any_secret_value".

This key is critical for security, as without it Flask will not be able to handle session information securely.

Importing and using Flash

To use flash messages, we need to import the corresponding function:

from flask import flash

Then, we can create flash messages at any point in our code, especially after important actions:

# After creating a note successfullyflash("Note created", "success").

The first parameter is the message we want to display, and the second is the category. Categories are useful to apply different styles depending on the type of message (success, error, warning).

Displaying the messages in the template

To display the messages in our HTML template, we use Jinja2's get_flashed_messages() function:

{% with messages = get_flashed_messages(with_categories=true) %} {% if messages %} <ul> {% for category, message in messages %} <li class="{{ category }}">{{ message }}</li> {% endfor %} </ul> {% endif %}{% endwith %}

This code:

1. Retrieves flash messages with their categories.
2. Checks if there are messages to display
3. Iterates over each message, displaying it in a list item.
4. Applies the category as a CSS class to allow for different styles

How to improve the presentation of Flash Messages?

Basic flash messages work, but for an optimal user experience, it is advisable to improve their visual presentation:

Using CSS frameworks

Frameworks like Tailwind CSS can help to significantly improve the appearance of our flash messages:

• For successful messages: classes with green backgrounds
• For errors: red backgrounds
• For warnings: yellow backgrounds

Category customization

We can create different categories according to our needs:

# Success messageflash("Note created successfully", "success")
 # Error messageflash("Could not create note", "error")
 # Warning messageflash("Note is empty", "warning")

Strategic positioning

It is important to place messages in visible but not intrusive places:

• Generally at the top of the page.
• Below the navigation bar
• With enough contrast to be noticed

Implementing flash messages is a best practice that significantly improves the user experience by providing clear feedback on actions taken. These small details make the difference between a basic web application and a professional one, where the user always knows what is happening with their actions. We encourage you to experiment with different styles and categories to find the combination that best suits your application.

Have you implemented flash messages in your projects? What other techniques do you use to improve the user experience in your web applications? Share your experience in the comments.