CRUD Operations in Slim Framework

What is CRUD?

CRUD is an acronym for Create, Read, Update, and Delete. It is a set of operations that are used to manage data in a database.

This guide walks you through creating a new resource with complete CRUD operations in your Slim MVC application.

Prerequisites

• Familiar with MVC pattern and the provided Slim Skeleton Project ↗-
• Understand the BaseController methods (render() and redirect())
• Understand the BaseModel methods
• Familiar with PSR-7 Request/Response objects

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Step 1: Create the Controller

1. Create a new controller class in app/Controllers/ (if it doesn’t exist)
2. Name it using PascalCase with “Controller” suffix (e.g., ProductController.php)
3. Extend BaseController and add constructor with proper parent call
4. Implement these standard callback methods:
   • index() → Display a list of items (GET request).
   • show() → Show details of a single item (GET request).
   • create() → Display a form to create a new item (GET request).
   • store() → Handle a request to save a new item to the database (POST request).
   • edit() → Display a form to edit an item (GET request).
   • update() → Handle a request to save changes to an item (POST request).
   • delete() → Handle a request to delete an item (GET request).

Remember

These methods are called by the router when a request is made to the corresponding route.

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Controller Constructor and Callback Methods Signatures

<?php

use Psr\Http\Message\ResponseInterface as Response;
use Psr\Http\Message\ServerRequestInterface as Request;

class YourController extends BaseController  // e.g., ProductsController
{
    // Constructor
    public function __construct(Container $container, private YourModel $model) // inject your model into the controller constructor
    {
        parent::__construct($container);
    }

    // Signatures of controller methods: (callback methods)
    public function index(Request $request, Response $response, array $args): Response // GET request
    public function show(Request $request, Response $response, array $args): Response // GET request
    public function create(Request $request, Response $response, array $args): Response // GET request
    public function store(Request $request, Response $response, array $args): Response // POST request
    public function edit(Request $request, Response $response, array $args): Response // GET request
    public function update(Request $request, Response $response, array $args): Response // POST request
    public function delete(Request $request, Response $response, array $args): Response // GET request
}

Remember

The $request parameter is the PSR-7 request object, the $response parameter is the PSR-7 response object, and the $args parameter is an array of route parameters.

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Step 2: Create View Templates

1. Create a folder in app/Views/ matching your resource (e.g., products) name (lowercase) (if it doesn’t exist)
2. Create these view files:
   • resource-name.IndexView.php => List view
   • resource-name.ShowView.php => Detail view
   • resource-name.CreateView.php => Creation form
   • resource-name.EditView.php => Edit form

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Step 3: Register Routes

1. Open app/Routes/web-routes.php
2. Import your controller at the top with other use statements
3. Add routes inside the return function using this pattern:

Route Naming Convention

Follow the pattern: [controller_name].[method_name]

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Understanding URI Design and Resource Identification

Why Use URIs to Identify Resources?

URIs (Uniform Resource Identifiers) serve as unique addresses for your application’s resources. Think of them like street addresses - each resource needs a clear, predictable location.

Remember

URIs are used to identify resources in your application.

Key Benefits:

• Predictability: Users and developers can guess URIs
• SEO-friendly: Search engines prefer meaningful URIs
• Maintainability: Consistent patterns make code easier to maintain
• REST Compliance: Follows web standards and best practices

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Using RESTful URI Principles in your application

1. Use Nouns, Not Verbs

✅ Good: /products (noun - represents the resource) ❌ Bad: /getProducts (verb - describes the action)

2. Use Plural Nouns for Collections

✅ Good: /products (collection of products) ❌ Bad: /product (ambiguous - single or multiple?)

3. Use Hierarchical Structure

✅ Good: /products/123/reviews (reviews for product 123) ❌ Bad: /reviews?product_id=123 (less intuitive)

4. Be Consistent with Casing

✅ Good: /products/categories (all lowercase) ❌ Bad: /Products/Categories (mixed case)

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Standard CRUD URI Patterns

Action	HTTP Method	URI Pattern	Example
List all	GET	/resources	/products
Show one	GET	/resources/{id}	/products/123
Create form	GET	/resources/create	/products/create
Store new	POST	/resources	/products
Edit form	GET	/resources/{id}/edit	/products/123/edit
Update	POST	/resources/{id}	/products/123
Delete	GET	/resources/{id}/delete	/products/123/delete

Why This Pattern Works

• Users can guess URIs: if /products lists all products, then /products/123 likely shows product 123,
• Developers can quickly understand what each route does,
• Consistency reduces bugs and improves team collaboration.

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Standard Web Routes (CRUD)

Add these routes to your web-routes.php file for complete CRUD functionality:

// 1) List all resources (GET /resource-name) e.g., GET /products
$app->get('/resource-name', [YourController::class, 'index'])
    ->setName('resource.index');

// 2) Show single resource (GET /resource-name/{id}) e.g., GET /products/1
$app->get('/resource-name/{id}', [YourController::class, 'show'])
    ->setName('resource.show');

// 3) Show a form to create a new resource (GET /resource-name/create) e.g., GET /products/create
$app->get('/resource-name/create', [YourController::class, 'create'])
    ->setName('resource.create');

// 4) Handle a request to save a new item to the database (POST /resource-name) e.g., POST /products
$app->post('/resource-name', [YourController::class, 'store']);

// 5) Show a form to edit an existing resource (GET /resource-name/{id}/edit) e.g., GET /products/1/edit
$app->get('/resource-name/{id}/edit', [YourController::class, 'edit'])
    ->setName('resource.edit');

// 6) Handle a request to save changes to an existing resource (POST /resource-name/{id}) e.g., POST /products/1
$app->post('/resource-name/{id}', [YourController::class, 'update']);

// 7) Handle a request to delete an existing resource (GET /resource-name/{id}/delete) e.g., GET /products/1/delete
$app->get('/resource-name/{id}/delete', [YourController::class, 'delete'])
    ->setName('resource.delete');

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Step 4: Create the Model

1. Create a model class in app/Domain/Models/ (e.g., ProductsModel.php) (if it doesn’t exist)
2. Implement methods for data operations in the model:
   • getAll() => Retrieve all records (SELECT query)
   • getById($id) => Get a single record (SELECT query)
   • create($data) => Insert a new record (INSERT query)
   • update($id, $data) => Update an existing record (UPDATE query)
   • delete($id) => Remove an existing record (DELETE query)
3. Follow the MVC pattern - models handle data, controllers coordinate, views display

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Step 5: Implement Controller Logic

1. Inject your model into the controller constructor (if not already done)
2. Use the model methods for all data operations
3. Use $this->render() to display views with data from models
4. Use $this->redirect() for navigation after form submissions
5. Extract route parameters using $args['parameter_name']
6. Get form data using $request->getParsedBody()
7. Validate input data before passing to model methods
8. Handle errors gracefully with appropriate redirects

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Step 6: Test Your Routes

1. Start your development server
2. Visit each route in your browser
3. Test form submissions
4. Verify redirects work correctly
5. Check error handling

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Important Notes

• Route order matters: Place specific routes (like /create) before parametric routes (like /{id})
• Named routes: Always use ->setName() for routes you’ll redirect to
• URI args vs query params: Use $args only for routes with {placeholders}, use $request->getQueryParams() for ?key=value
• POST-Redirect-GET: Always redirect after successful form submissions to prevent duplicate submissions

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Example File Structure

After following these steps, you should have:

app/
├── Controllers/
│   └── YourController.php   👉 (e.g., ProductsController.php)
├── Models/
│   └── YourModel.php        👉 (e.g., ProductsModel.php)
├── Views/
│   └── your-resource/       👉 (e.g., products)
│       ├── resource-name.IndexView.php      👉 (e.g., products.IndexView.php)
│       ├── resource-name.ShowView.php       👉 (e.g., products.ShowView.php)
│       ├── resource-name.CreateView.php     👉 (e.g., products.CreateView.php)
│       └── resource-name.EditView.php       👉 (e.g., products.EditView.php)
└── Routes/
    └── web-routes.php (updated)

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MVC Pattern Reminder

Remember to follow the MVC pattern throughout your implementation:

• Models: Handle all data operations, database queries, and business logic
• Views: Display data and handle user interface
• Controllers: Coordinate between models and views, handle HTTP requests/responses

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Next Steps

• Add validation to your controller methods
• Implement proper model classes with database operations
• Add error handling and user feedback
• Style your views with CSS
• Add authentication/authorization if needed
• Consider implementing advanced search features (autocomplete, faceted search)
• Add export functionality for filtered results