**Laravel 12 API Development - Lecture 4: Controllers, Request Lifecycle & API Structure**
---
# Lecture 4
### ✅ Lecture Objective:
By the end of this 3-hour lecture, trainees will:
- Understand Laravel's request lifecycle clearly.
- Learn how Laravel handles API requests from start to finish.
- Create and organize API controllers using best practices.
- Understand route grouping, prefixing, and route methods (GET, POST, etc.).
---
## ⭐ 1. Laravel Request Lifecycle (40 min)
Welcome, everyone! Let's start today by understanding **how Laravel handles your request**. Imagine you open Postman and hit:
```
GET http://localhost:8000/api/v1/experts
```
### Step-by-step Lifecycle:
1. The request enters the Laravel app through `public/index.php`, the **entry point** of all HTTP requests.
2. Laravel loads the **HTTP Kernel**, defined in `App\Http\Kernel.php`, which handles global and route middleware (like `auth`, `throttle`, etc.).
3. Laravel checks your request URL and method (GET, POST, etc.) and tries to find a matching route in `routes/api.php`.
4. If it finds the route, it calls the **corresponding controller method**, for example, `ExpertController@index`.
5. The controller might use a **Model** to fetch or store data, then returns a **response**.
6. Laravel sends back a **JSON response** (since it's API), often with a status code.
> 🧠 Always remember: Laravel does a lot behind the scenes. Our job is to define **routes**, **controllers**, and **models** properly.
---
## 📕 2. Laravel Routing Basics (50 min)
Laravel handles routes in the `routes/api.php` file. This file is automatically created for every Laravel app.
### How to Create or View `api.php`:
You don't need to generate it; it already exists. Check:
```
routes/api.php
```
Use this for **API-only routes**.
### Common Route Methods:
```php
Route::get('/experts', [ExpertController::class, 'index']);
Route::post('/experts', [ExpertController::class, 'store']);
Route::put('/experts/{id}', [ExpertController::class, 'update']);
Route::delete('/experts/{id}', [ExpertController::class, 'destroy']);
Route::get('/experts/{id}', [ExpertController::class, 'show']);
```
Each one maps to a method inside a controller. These are called **HTTP verbs**, and they represent CRUD:
- GET = Read
- POST = Create
- PUT = Update
- DELETE = Delete
### Route Groups & Prefixing
```php
Route::prefix('v1')->group(function () {
Route::apiResource('experts', ExpertController::class);
});
```
### apiResource - Full CRUD Generator
```php
Route::apiResource('experts', ExpertController::class);
```
Laravel automatically assumes controller method names like `index`, `store`, `show`, etc.
---
## 📄 3. Creating API Controllers (25 min)
### Basic Controller
```bash
php artisan make:controller Api/ExpertController
```
### Resource Controller
```bash
php artisan make:controller Api/ExpertController -r
```
Includes:
- index(), store(), show(), update(), destroy()
> ✍️ Use `-r` for full CRUD structure with REST APIs.
---
## 📝 4. Form Request Validation (30 min)
### Create Request
```bash
php artisan make:request StoreExpertRequest
```
### Example Rules:
```php
public function rules(): array
{
return [
'name' => 'required|string|max:100',
'bio' => 'nullable|string|max:500',
'industry' => 'required|string|max:100',
'category' => 'nullable|string',
'experience_years' => 'nullable|integer|min:0',
];
}
```
Used inside controller like this:
```php
public function store(StoreExpertRequest $request)
{
$validated = $request->validated();
$expert = Expert::create($validated);
return response()->json($expert, 201);
}
```
---
## 📂 5. Creating & Understanding Models (Users First) (45 min)
### Create User Model and Migration:
```bash
php artisan make:model User -m
```
Edit the migration:
```php
$table->string('name');
$table->string('email')->unique();
$table->string('password');
$table->timestamps();
```
Then:
```bash
php artisan migrate
```
This creates `users` table in `database/database.sqlite`
### Use DB Browser for SQLite
- Download "DB Browser for SQLite"
- Open the file: `database/database.sqlite`
- Browse tables, insert/edit rows, run queries
### Create Expert Model after User:
```bash
php artisan make:model Expert -m
```
Migration should include:
```php
$table->string('name');
$table->text('bio')->nullable();
$table->string('industry');
$table->foreignId('user_id')->constrained('users');
```
Run:
```bash
php artisan migrate
```
> ⚠️ Migrations must be done in order: User first, Expert second.
---
## 📈 6. Implementing CRUD - First with Dummy Data, Then DB (40 min)
### Phase 1: Dummy Data
```php
public function index()
{
return response()->json([
['id' => 1, 'name' => 'Dr. Lina'],
['id' => 2, 'name' => 'Mr. Karim']
]);
}
```
### Phase 2: With DB
```php
public function index()
{
return response()->json(Expert::all());
}
```
The same for:
- `store()` with `Expert::create()`
- `show()` with `Expert::findOrFail()`
- `update()` with `$expert->update()`
- `destroy()` with `$expert->delete()`
> 🧪 Test both phases to see the difference between static and dynamic APIs.
---
## 🛠 Project Tip: Model Implementation Order (10 min)
Recommended order to prevent FK issues:
1. `User` - base model
2. `Expert` - linked to user
3. `Booking` - links both
4. Later: Reviews, Messages, Ratings, etc.
---
## 📃 Assignment
1. Create User & Expert models + migrations
2. Migrate both tables in SQLite
3. Create `ExpertController` with CRUD
4. Start with dummy data, then switch to DB
5. Use FormRequest for validation
6. Browse SQLite with DB Browser
7. Test all endpoints with Postman
---
## Resources
### API design text file
```
Get List of users endpoint
http://DomainNameOrIP.com/ BASE URL
Resource ENDPOINT + HTTP VERB
prefix: /api
/users/get
FULL API ENDPOINT:
http://DomainNameOrIP.com/PREFIX/users/get GET
http://DomainNameOrIP.com/api/users/get GET
USers is RESOURCE
Response is list of users as JSON format
--------------- Create new user ENDPOINT (Specification)----------
Resource: users/add POST
name
email
userId
Body:
{
"name":"",
"email":"",
"userId":""
}
<=>
[
'name'=>'',
'email'=>'',
'userId'=>''
]
in controller of create user, extract inputs from the http request body
response should be http status code 200
---------------------------------------------------
- Produce api.php file in routes directory
- Create endpoint to get list of experts with below fields:
fullName
industry
age
country
- Create endpoint to create new expert in the system :
fullName : mandatory, minimum length is 3 and max is 15
industry: programming, payment, engineering
age: 18 - 125
country: iraq, UAE, jordan
response is json
CRUD:
Create, READ, Update, Delete
/api/users GET (get all)
/api/users POST (store new user)
/api/users/{ID} PATCH/PUT (update already exists user)
/api/users/{ID} DELETE
```
End of Lecture 4
## Git and Github
Case 1: if you have to initialize git repo by your self and push it into the github
first, go to Github and create new repo
then
```
git init
git add *
git commit -m 'your message'
git branch -M main
git remote add origin GITHUB_URL
git push -u origin main
```
case 2:
in case you want to clone a remote repo into your machine
```
```
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