Building Laravel Image API

Welcome to the fifth lesson of our course on building an image generation service with PHP Laravel! In our previous lessons, we've built several key components of our application: the PromptManager for formatting user inputs, the ImageManager for storing and processing images, the ImageGeneratorService for connecting to the Gemini API using the generateContent flow with gemini-3.1-flash-image, and, most recently, the ImageGeneratorController, which handles input validation and response formatting.

Now it's time to bring everything together by creating a Laravel application that will expose our functionality through HTTP endpoints. This is the final piece of our backend architecture that will allow users to interact with our image generation service through a web interface.

In the previous lesson, we built the ImageGeneratorController, which acts as an intermediary between our service layer and the API routes we'll create today. The controller handles the business logic of validating inputs, calling the appropriate service methods, and formatting responses. Now, we'll create the Laravel routes that will receive HTTP requests from clients and pass them to our controller.

Our Laravel API will have three main routes:

1. A route to serve the main HTML page
2. A route to handle image generation requests
3. A route to retrieve all previously generated images

By the end of this lesson, you'll have a complete Laravel API that integrates with the controller we built previously, providing a clean interface for clients to generate and retrieve images.

Let's start by creating our Laravel application. We'll set up the basic structure in our routes/api.php file:

<?php

use App\Http\Controllers\ImageGeneratorController;
use Illuminate\Support\Facades\Route;

Route::post('/generate_image', function (\Illuminate\Http\Request $request) {
    $userInput = $request->input('user_input');
    $aspectRatio = $request->input('aspect_ratio', '1:1'); // Default to 1:1 if missing
    return app(ImageGeneratorController::class)->generateImage($userInput, $aspectRatio);
});

In this code, we're using the Laravel framework to create our application. We start by importing the ImageGeneratorController class and the Route facade from Laravel.

We define a POST route for /generate_image that handles image generation requests. This route extracts the user_input from the request and passes it to the generateImage method of our ImageGeneratorController.

Now that we have our Laravel application set up, let's define the routes that will handle client requests.

We'll start with the index route, which will serve the main HTML page of our application:

Route::get('/', [ImageGeneratorController::class, 'index']);

This route uses the get method to specify that it should be called when a client requests the root URL of our application. The index method of the ImageGeneratorController returns the main HTML page.

Next, let's define the route for generating images:

Route::post('/generate_image', function (\Illuminate\Http\Request $request) {
    $userInput = $request->input('user_input');
    $aspectRatio = $request->input('aspect_ratio', '1:1'); // Default to 1:1 if missing
    return app(ImageGeneratorController::class)->generateImage($userInput, $aspectRatio);
});

This route is more complex than the index route. The post method specifies that this function should be called when a client sends a POST request to the /generate_image URL.

Inside the function, we extract the user_input from the request. We then pass this input to our controller's generateImage method, which will validate the input, call the service to generate an image via the Gemini API using generateContent with gemini-3.1-flash-image, and format the response.

Finally, let's define the route for retrieving all previously generated images:

Route::get('/get_images', [ImageGeneratorController::class, 'getImages']);

This route is defined with the get method, which specifies that it should be called when a client sends a GET request to the /get_images URL.

The function simply calls our controller's getImages method, which retrieves all stored images and formats them as a JSON response.

With these three routes, our Laravel API provides a complete interface for clients to interact with our image generation service. Clients can view the main page, generate new images, and retrieve previously generated ones.

Now that we have our Laravel application and routes defined, let's configure the server to run our application. You can start the Laravel development server by navigating to the root directory of your Laravel project in your terminal and running:

php artisan serve

This command starts a Laravel development server, which you can access by opening a web browser and navigating to the URL provided in the terminal output.

In this lesson, we've built a complete Laravel API that integrates with our ImageGeneratorController to provide a web interface for our image generation service. Let's review what we've accomplished:

1. We set up a Laravel application, including defining routes for handling client requests.
2. We created an index route to serve the main HTML page of our application.
3. We implemented a POST endpoint for generating images, which extracts user input from the request and passes it to our controller.
4. We set up a GET endpoint for retrieving all previously generated images.
5. We configured the Laravel server to run using the built-in development server.

Our Laravel API now provides a complete interface for clients to interact with our image generation service. The API routes receive HTTP requests, extract the necessary data, and pass it to our controller, which handles the business logic of validating inputs, calling the appropriate service methods, and formatting responses.

This completes the server-side portion of our image generation application. We've built a robust, modular architecture with a clear separation of concerns:

• The PromptManager handles prompt formatting.
• The ImageManager manages image storage and processing.
• The ImageGeneratorService connects to the Gemini API, sending formatted prompts to gemini-3.1-flash-image via the generateContent endpoint and extracting the returned image data.
• The ImageGeneratorController validates inputs and formats responses.
• The Laravel API routes client requests to the appropriate controller methods.

In the upcoming practice exercises, you'll have the opportunity to test the API endpoints we've created. You'll send requests to generate images with different prompts and retrieve the stored images. You'll also explore how the API handles error cases, such as missing or invalid inputs.

By the end of these exercises, you'll have a solid understanding of how to build a complete web API with Laravel, integrating it with a controller-based architecture to provide a clean, consistent interface for clients. This knowledge will be valuable not just for image generation services but for any web application you build in the future.