Building an Interactive Web Application with Flask REST API
If you’re looking to build an interactive web application, Flask REST API is one of the most popular back-end frameworks available for Python. With its simplicity and flexibility, it’s a great choice for building web applications that require fast and efficient communication between the front-end and back-end.
Prerequisites
Before we get started with Flask REST API, we need to make sure that we have certain prerequisites in place. You’ll need to have a basic understanding of Python and Flask, as well as some knowledge of databases and SQL.
If you’re new to Python, it’s worth investing some time into learning the basics before diving into Flask REST API.
Grab the Back-End Code
The first thing we need to do is grab the back-end code for our web application. Flask REST API provides a great starting point for building web applications, with all the basic functionality you need to create a simple API.
Install the Requirements
Once you have the back-end code, the next step is to install all the required dependencies. Flask REST API has a number of dependencies that need to be installed before you can run the application.
Create the Database
With the dependencies installed, we can now create our database. Flask REST API supports a range of SQL databases, including MySQL, PostgreSQL, and SQLite.
For this tutorial, we’ll be using SQLite, as it’s a lightweight and easy-to-use database that’s perfect for small to medium-sized web applications.
Check Your Flask Project
Now that everything is set up, let’s take a look at our Flask project. Flask is a micro web framework that provides a simple and flexible way to create web applications.
By default, Flask REST API sets up a basic Flask application, with a single endpoint that returns a simple “Hello, World!” message.
Addressing Shortcomings of Flask REST API
While Flask REST API is a great framework, there are a few shortcomings that can hinder the development of a complex web application. In this section, we’ll take a look at how to address some of these shortcomings.
Investigate the Project Structure
One of the main issues with Flask REST API is its project structure. The standard Flask project structure is not suitable for large and complex web applications, as it can quickly become unwieldy and difficult to manage.
To address this, we need to restructure the project to make it more modular and organized.
Fix Your Model
Another common issue with Flask REST API is its lack of support for database models. While Flask provides a simple way to interact with databases, it doesn’t offer any built-in support for creating and managing database models.
To fix this, we need to create a Flask model that maps to our database schema.
Adjust Your Flask Functions
Finally, we need to adjust our Flask functions to work with our new project structure and database model. We need to create new functions that handle the different requests we want to handle, and modify our existing functions to use our new database model.
Conclusion
Flask REST API is a great starting point for building a simple web application, but it has its limitations. By addressing some of these shortcomings, we can create a more robust and flexible web application that can handle more complex scenarios.
By restructuring our project, creating a Flask model, and adjusting our Flask functions, we can build a web application that is both powerful and easy to maintain.
3) Building Front-End Components
Now that we’ve built the back-end of our web application with Flask REST API, we need to focus on the front-end. In this section, we’ll take a look at how to build front-end components using HTML, JavaScript, and CSS.
Nest Your HTML Templates
When building web applications with Flask, we use the Jinja templating engine to create dynamic HTML templates. Templates allow us to reuse HTML code and create a consistent look and feel across our web application.
One way to make our templates even more modular is to nest them. By breaking down our templates into smaller, reusable components, we can make our code more readable and easier to maintain.
For example, we can create a navigation bar component that can be used across all our pages.
Sprinkle in Some JavaScript
JavaScript is a powerful scripting language that allows us to create dynamic and interactive web pages. By adding some JavaScript to our web application, we can make it more intuitive for users.
One way to use JavaScript in our web application is to create client-side form validation. For example, we can use JavaScript to validate that a user has entered a valid email address or that they have entered a password with at least one uppercase letter, one lowercase letter, and one number.
Style Your Front End
CSS allows us to customize the look and feel of our web application. By creating a consistent and visually appealing design, we can make our web application more professional and engaging for users.
One way to style our web application is to use CSS frameworks, such as Bootstrap or Foundation, which provide pre-designed CSS styles and components that we can use in our web application. For example, we can use a pre-designed button component, rather than designing our own button from scratch.
4) Modularizing Flask Projects JavaScript Code
In the previous section, we covered how to build front-end components using HTML, JavaScript, and CSS. In this section, we’ll take a look at how to modularize our JavaScript code in our Flask project.
Create Your First External JavaScript File
When working with JavaScript in Flask, it’s best practice to keep our JavaScript code in an external file, rather than embedding it directly in our HTML templates. This allows us to keep our code organized and easy to manage.
To create an external JavaScript file, we need to create a new file with a .js extension and include it in our HTML template using the script tag.
Distribute Some JavaScript Logic
As our web application becomes more complex, we may find that we’re repeating the same JavaScript logic across multiple pages. To avoid this, we can distribute some of our JavaScript logic into reusable functions or modules that can be used across our web application.
For example, we can create a validation module that contains functions for validating email addresses, passwords, and other form inputs. We can then include this module in our external JavaScript file and use it across all our pages.
Connect JavaScript With HTML
Once we have our external JavaScript file and reusable modules in place, we need to connect our JavaScript code with our HTML templates. We can do this by selecting HTML elements using their ID or class attribute and then using JavaScript to manipulate or interact with these elements.
For example, we can select a form element using its ID and then add an event listener to detect when the form is submitted. We can then use JavaScript code to validate the form inputs and display error messages if necessary.
Conclusion
By building front-end components using HTML, JavaScript, and CSS, and modularizing our JavaScript code in our Flask project, we can create a robust and organized web application that provides a great user experience. With the ability to create re-usable components, distribute our JavaScript code, and connect our JavaScript with our HTML templates, we can easily extend our web application as needed.
5) Creating People
One of the core features of our web application is the ability to create and manage people. In this section, we’ll take a look at how to build the front-end components for creating people using HTML, CSS, and JavaScript.
The HTML
To create a form for adding a new person to our web application, we need to start with the HTML code. We can use a simple HTML form that includes fields for the person’s name, age, and email address.
We’ll also need to include a button to submit the form.
The CSS
Once we have our HTML code in place, we can style it using CSS to make it look more visually appealing. We can use CSS to customize the color and font of our form elements, as well as the layout of our form.
One technique we can use to style our form is to create a CSS class that defines the styles we want to apply to our form elements. We can then apply this class to all the form elements that we want to style in the same way.
The JavaScript
Finally, we need to add some JavaScript to handle the form submission and communicate with our Flask back-end. We can add an event listener to our form button that listens for clicks.
When the button is clicked, we can extract the values from the form fields and send them to our back-end using an AJAX request. We can use the Fetch API to send the AJAX request to our Flask back-end.
We’ll need to include the URL of our Flask API endpoint, as well as the data from our form fields, in the request. Once the request is complete, we can display a success message to the user.
6) Creating Notes
Another important feature of our web application is the ability to create and manage notes. In this section, we’ll take a look at how to build the front-end components for creating notes using HTML, CSS, and JavaScript.
The HTML
To create a single-page web application for adding and managing notes, we need to start with the HTML code for our page. We can use a simple HTML template that includes a textarea element for the note content and a button to submit the note.
One technique we can use to create a single-page web application is to use JavaScript to update the content of our page dynamically. When the user clicks the submit button, we can use JavaScript to create a new note element and append it to our existing list of notes on the page.
The CSS
Once we have our HTML code in place, we can style it using CSS to make it look visually appealing. We can use CSS to customize the color and font of our note elements, as well as the layout of our page.
One technique we can use to style our notes is to create a CSS class that defines the styles we want to apply to our note elements. We can then apply this class to all the note elements that we create dynamically using JavaScript.
The JavaScript
Finally, we need to add some JavaScript to handle the note creation and display. We can add an event listener to our submit button that listens for clicks.
When the button is clicked, we can extract the value from the textarea and create a new note element using JavaScript. We can use the createElement method to create a new note element, and the appendChild method to add it to our list of notes on the page.
We can also use the innerHTML property to set the content of our note element to the value of our textarea.
Conclusion
By building front-end components for creating people and notes using HTML, CSS, and JavaScript, we can create a robust and visually appealing web application. With the ability to customize the style of our forms and notes using CSS, and dynamically update the content of our page using JavaScript, we can create a great user experience.
By using techniques like modularizing our JavaScript code and creating CSS classes, we can keep our code organized and maintainable.
7) Editing a Person
Another important feature of our web application is the ability to edit existing people. In this section, we’ll take a look at how to build the front-end components for editing a person using HTML, CSS, and JavaScript.
We’ll also cover how to debug any issues we might encounter along the way.
The Bug
Before we can start building the edit person feature, we need to address a bug that’s affecting our existing code. When we try to load the details of a specific person, we get an error message in our console that says “TypeError: Cannot read property ‘name’ of undefined”.
The first step in debugging this issue is to isolate the problem. We can start by inspecting our code and seeing where the error is being thrown.
After some investigation, we can see that the issue is being caused by an incorrect URL parameter. Our Flask API expects a URL parameter with the name “person_id”, but our JavaScript code is using the parameter name “id”.
Once we correct the parameter name in our JavaScript code, the error goes away.
The HTML
With the bug fixed, we can now move on to building the HTML code for editing a person. We can use a simple HTML form that includes fields for the person’s name, age, and email address.
We’ll also need to include a button to submit the form. To pre-populate the form with the existing details of the person we want to edit, we can include the current values as default values for the form fields.
The CSS
Once we have our HTML code in place, we can style it using CSS to make it look visually appealing. We can use CSS to customize the color and font of our form elements, as well as the layout of our form.
One technique we can use to style our form is to create a CSS class that defines the styles we want to apply to our form elements. We can then apply this class to all the form elements that we want to style in the same way.
The JavaScript
Finally, we need to add some JavaScript to handle the form submission and communicate with our Flask back-end. To do this, we’ll need to extract the values from the form fields and send them to our back-end using an AJAX request, just like we did when creating a new person.
We’ll also need to update our Flask API to handle updating an existing person. To do this, we can create a new route that accepts a PUT request and updates the details of the person with the given ID.
Next Steps
Now that we’ve added the ability to edit existing people in our web application, we can move on to adding additional features. For example, we can add the ability to delete people or manage notes for each person.
We can also look for more ways to optimize our code and improve the user experience. By continuing to add new features and improvements over time, we can create a web application that’s both powerful and easy to use.
In this article, we explored how to build a web application using Flask REST API, HTML, CSS, and JavaScript. We learned how to create front-end components for creating and editing people and notes, and how to debug any issues we encounter along the way.
By modularizing our code and using best practices like separating our JavaScript code from our HTML templates, we can create a robust and maintainable web application that provides a great user experience. Moving forward, we can continue to add new features and optimizations to make our web application even better.
The key takeaway is that building a web application with Flask REST API and modern web development techniques is an exciting and rewarding project that can help us improve our coding skills and create something that’s useful and engaging for others.