FE-001: Connecting Authentication Forms To Backend

Oct 27, 2025 by SLV Team 51 views

Hey guys! So, we've got these cool login (LoginForm.jsx) and signup (SignUpForm.jsx) forms in our UI, but they're basically just pretty faces right now, not doing anything real. This is where we roll up our sleeves and get them connected to the backend! This task is all about hooking those forms up to the API endpoints that handle authentication (/api/auth/login and /api/auth/register). Let's dive in and get this done!

The Goal: User Authentication Magic

Our ultimate aim, the big picture, is to let users actually sign up and log in to our platform using the data they enter in the AuthModal. Think of it: users fill in their details, click a button, and voila – they're in! That's the power of connecting our frontend forms to the backend authentication system. It's about turning those static forms into dynamic gateways that grant access to our awesome platform. So, let's make this happen and provide a seamless user experience. By implementing this feature, we're not just creating a login and signup process; we're building the foundation for user accounts, personalized content, and a whole lot more! We need to make sure everything works perfectly.

Authentication Forms to Backend: A Step-by-Step Guide

To make this happen, we need to do some specific stuff. Follow these steps to make sure the connection goes smoothly.

Step 1: HTTP Request Library Time

The first thing is to install a library that'll help us make HTTP requests. You can go with a popular one like axios or use the built-in fetch API. Both are cool, but axios is super popular. If you're new, don't worry, fetch will get the job done! This library is what we will use to send the data from our forms to our backend. It's the messenger that helps our frontend talk to the backend, enabling the exchange of information to make the whole authentication process work.

Step 2: Login Form - The Art of Submitting Data

Let's get into the LoginForm.jsx. Here's what we need to do with the handleSubmit function:

Send a POST Request: We're going to send the email and password entered by the user via a POST request to the /api/auth/login endpoint. This is the pathway to authenticating a user. This means our frontend will package up the email and password, and send it to our backend to verify the credentials. Our backend will work its magic, and respond with either success or failure.
Handle Success (JWT Token): If the login is successful (we receive a JWT – JSON Web Token), we'll store that token (maybe in localStorage). This token is a key to unlock the user's access. The next step is to call the onAuthSuccess function (which comes from App.jsx). This function updates the global isLoggedIn state. In simpler words, it's a flag that changes from false to true after a successful login. This update triggers changes in the user interface, showing the user that they are now logged in. The token is our secret key. It allows the user to access protected resources.
Handle Errors: If something goes wrong (invalid credentials, network issues, etc.), we need to show an error message to the user. This is crucial for a good user experience. We use the error message from the backend to inform the user about the situation, and suggest a resolution to the problem.

Step 3: Signup Form - Creating New Accounts

Now, let's move on to the SignUpForm.jsx. Here's the plan for the handleSubmit function:

Send All the Data: We're going to send all the form data (firstName, lastName, cpf, etc.) to /api/auth/register via a POST request. This is the process of creating a new user account on the backend. This data includes all the necessary information to create a new user account, like name, email, and password. The backend receives the information, validates it, and if everything checks out, creates a new user in the database.
Handle Success: If the signup goes well, show a success message to the user. You could close the modal, redirect them to the login screen, or just let them know they've been registered. This ensures that the user is informed of the result of the action they took. It's a key part of the feedback, telling the user what happens and what they can do next.
Handle Errors: If there's an issue (email already in use, invalid data), show the error message returned by the API to the user. This error handling is key, helping to guide the user in correcting their input or understanding the reason for the signup failure.

Step 4: Visual Feedback: Making it Smooth

We need to add visual feedback in both forms! How? By disabling the button during the sending process. This gives the user a signal that their request is being processed. It's super important for user experience; the visual changes reassure the user that their action is being processed and prevent accidental double-submissions.

Acceptance Criteria: The Checklist

These are the requirements to complete the task:

Successful Signup: A user should be able to sign up with valid data through the form.
Clear Error Messages: If signup fails (like a duplicate email), the user should see a clear error message.
Successful Login: A user should be able to log in with valid credentials.
UI Update After Login: After a successful login, the isLoggedIn state should update, and the UI should reflect this (e.g., the profile icon changes).
Clear Error Messages During Login: If the login fails, the user should see clear error messages.

By following these steps, you'll successfully integrate your authentication forms with the backend. Good luck, and have fun building!

Going Further

Error Handling: Implement comprehensive error handling. Catch all possible errors from the backend and present user-friendly messages.
Loading Indicators: Show loading indicators during API requests to provide feedback.
Input Validation: Validate the data on the frontend to improve user experience and reduce unnecessary requests.
Password Security: Ensure the password is secure, following best practices.

With these steps and considerations, you'll be well on your way to building robust and user-friendly authentication features.

Detailed Breakdown for each form

Let's deep dive into the specific actions needed for each form. This is where the rubber meets the road! Remember, it's all about making the forms communicate effectively with the backend, handling responses gracefully, and keeping the user in the loop. The details are important. Let's make sure the forms do what they're meant to do!

Login Form Breakdown

The Login Form is all about verifying a user's identity. When the user enters their email and password and clicks the submit button, our front-end application should make a call to our backend. This call should have a POST type with the login endpoint, as we previously discussed. Here's a deeper look:

Event Handler Setup: Within the LoginForm.jsx, the handleSubmit function should start by preventing the default form submission behavior (that is, refreshing the page). This is typically done with event.preventDefault(). This way, we take control of the form submission process and can handle it asynchronously, without the page refreshing.
Collect Form Data: Gather the user's email and password from the form's input fields. This means accessing the current values of the email and password input fields. These are the two essential pieces of information we need to authenticate the user's identity.
Initiate API Request: Using the HTTP library we selected (like axios or fetch), make a POST request to the /api/auth/login endpoint. This is where we send the user's credentials to the backend for verification.
Send Credentials: Format the email and password into a JSON object that is compatible with the backend. This is important as the backend expects the data in a particular format. This JSON object needs to be included in the body of the POST request. This helps the backend parse the information correctly.
Handle the Response: This is the heart of the process. Handle the response in a couple of ways:
- Success: If the API call is successful (HTTP status 200), it probably returns a token. This token should be saved in localStorage (or a similar storage method). This token will allow the user to access protected resources. Then, the onAuthSuccess function from the App.jsx needs to be called to update the global state. This makes sure that the application knows the user is logged in. Remember, the user interface will change to reflect this, updating things like the navigation bar and user profile.
- Failure: If the API call fails (HTTP status other than 200), meaning the login attempt failed, we need to handle the errors. This is crucial for a good user experience. The backend will usually give a descriptive error message. This error message should be presented clearly to the user, telling them what went wrong (e.g., wrong password, user not found). You may display these error messages above the form fields or in a notification component.
Loading State: Before the API request, set a loading state to true. This will activate a visual indicator, like a spinner or a disabled button, to inform the user that their request is being processed. After the API request, set the loading state to false, regardless of success or failure.

Signup Form Breakdown

The Signup Form is designed to allow new users to register and join our platform. The steps are similar to the Login Form, but with different data and a slightly different process. Let's see what it involves:

Event Handler Setup: Within the SignUpForm.jsx, start by using the handleSubmit function to prevent the default form submission behavior. This control lets you handle the submission asynchronously.
Collect Form Data: Gather all form data from the signup form fields, such as firstName, lastName, email, password, cpf, and any other required fields. All the provided user data will be sent to the backend. Make sure to accurately collect all the necessary fields from the user.
Initiate API Request: Use the chosen HTTP library to make a POST request to the /api/auth/register endpoint. This is where we send the new user's registration data to the backend.
Send Registration Data: Format the registration data into a JSON object compatible with the backend. The API call needs to include this JSON object in the body of the POST request. Make sure that all fields match what the backend expects.
Handle the Response: Handle the API response:
- Success: If the signup is successful, show a success message to the user. This message could confirm successful registration. You might also redirect the user to the login page, close the signup modal, or update the UI to indicate the signup's success.
- Failure: If the signup fails, handle the errors. The API will usually provide a message for what went wrong. For example, if the email is already in use, the backend will return a specific error message. You have to display the error clearly to the user. This helps guide the user in understanding and fixing the problem, such as filling a unique email address.
Loading State: As with the login form, before the API request, set a loading state to true. This shows a visual indicator to the user that their request is being processed. After the API request completes (successfully or unsuccessfully), set the loading state to false.

Making It All Work Together

By following these steps for both the Login and Signup forms, you should now be able to connect your authentication forms to the backend. Always remember to handle different situations and provide feedback to the user, making sure they understand what is going on at every step.

Troubleshooting Tips and Tricks

It is important to keep in mind, that during the authentication process, a variety of issues might occur. Always ensure clear error messages and detailed logging. If an error appears, verify the following things:

Verify the Backend Endpoints: Double-check that the endpoints (/api/auth/login and /api/auth/register) are active and accessible. Also, check that they are correctly accepting POST requests and returning expected responses.
Check the Payload: Make sure that the JSON payload (containing email, password, and other fields) is sent correctly. Also, review the backend's API documentation, and make sure that the payload's format matches the expected format.
Browser's Developer Tools: Use the browser's developer tools (Network tab) to see the HTTP requests and responses. This can provide important information about the request's status, the headers, and the response body. This is a very valuable tool for debugging.
Backend Logs: Inspect the backend logs. They will include the details about the received requests, processing outcomes, and any exceptions or errors happening on the server. This is very important for diagnosing more advanced problems.

By ensuring the implementation of these steps, you will be able to construct a solid user authentication process, greatly improving the user experience and overall functionality of your application.