RESTful API Development with PHP
7 questions found
What is a RESTful API, and how do standard HTTP methods like GET, POST, PUT, and DELETE map to common data operations?
Beginner
A RESTful API is a style of web API design that treats data as a collection of resources, each identified by a specific URL, and uses standard HTTP methods to indicate the intended operation, with GET used for retrieving data, POST used for creating a new resource, PUT or PATCH used for updating an existing resource, and DELETE used for removing a resource, following widely understood conventions that make an API predictable and easy for other developers to use correctly.
GET /api/products // retrieve all products
POST /api/products // create a new product
PUT /api/products/5 // update product with id 5
DELETE /api/products/5 // delete product with id 5
Real-world example
An e commerce API follows RESTful conventions consistently, letting any developer familiar with REST immediately understand that sending a DELETE request to a specific product URL will remove that product, without needing to read detailed custom documentation for every single endpoint.
Common follow-ups: What is the difference between PUT and PATCH for updating a resource?;Why are RESTful conventions valuable even though HTTP technically allows you to design an API any way you want?
Routing & Middleware;JSON Handling in PHP
How does an API typically use HTTP status codes to communicate the result of a request, and what do common codes like 200, 404, and 500 represent?
Beginner
HTTP status codes provide a standardized way for an API to communicate the outcome of a request, with codes in the 200 range indicating success, such as 200 for a successful GET request or 201 specifically for a successful resource creation, codes in the 400 range indicating a client error, such as 404 for a resource that does not exist or 400 for a malformed request, and codes in the 500 range indicating a server side error, giving API consumers a reliable, consistent way to programmatically determine what happened without needing to parse the response body just to know if something succeeded or failed.
http_response_code(404);
echo json_encode(['error' => 'Product not found']);
Real-world example
An API correctly returns a 404 status code along with a clear error message when a requested product identifier does not exist, letting the client application easily detect and handle this specific situation using the status code alone.
Common follow-ups: What is the difference between a 401 and a 403 status code?;Why is it considered bad practice to always return a 200 status code even when an error actually occurred?
Error & Exception Handling;JSON Handling in PHP
How does authentication typically work for a RESTful API, and what is the difference between session based authentication and token based authentication using something like a JSON Web Token?
Intermediate
Session based authentication relies on a server side session, typically identified through a cookie, which works well for traditional web applications but is less ideal for APIs consumed by mobile apps or separate frontend applications, while token based authentication, commonly using a JSON Web Token, issues a self contained, cryptographically signed token to the client after successful login, which the client then includes with every subsequent request, letting the server verify the token's validity without needing to maintain any server side session state at all.
$token = JWT::encode(['user_id' => $user->id, 'exp' => time() + 3600], $secretKey, 'HS256');
// Client includes token in Authorization header on future requests
// Authorization: Bearer <token>
Real-world example
A mobile application authenticates against an API using a JSON Web Token, which is then included in the Authorization header of every subsequent request, letting the API remain completely stateless without needing to track individual user sessions on the server.
Common follow-ups: What information is typically encoded within a JSON Web Token's payload?;How do you securely handle token expiration and refreshing an expired token?
Security;Sessions & Cookies
How should a well designed RESTful API structure its endpoints and URL naming conventions to remain intuitive and consistent as it grows?
Intermediate
A well designed API typically uses plural nouns to represent resource collections, such as slash products rather than slash product, nests related resources logically, such as slash products slash five slash reviews for a specific product's reviews, uses query parameters for filtering, sorting, and pagination rather than encoding that information into the URL path itself, and maintains consistent naming conventions throughout, all of which make the API significantly more predictable and easier for other developers to learn and correctly use.
GET /api/products?category=electronics&sort=price&page=2
GET /api/products/5/reviews
Real-world example
An API design review catches an inconsistency where one endpoint used a singular resource name while every other endpoint used the plural convention, standardizing the naming before the API is published for external developers to consume.
Common follow-ups: How should an API handle versioning as its endpoints evolve over time?;What is the recommended approach for representing pagination information in an API response?
Routing & Middleware;JSON Handling in PHP
How does API rate limiting work, and why is it an important protection mechanism for a public facing RESTful API?
Intermediate
Rate limiting restricts how many requests a specific client, typically identified by an API key or IP address, can make within a given time window, protecting your API's backend resources from being overwhelmed by either legitimate heavy usage or a malicious attempt to abuse the API, and a well designed rate limited API typically communicates the current limit status back to the client through response headers, letting well behaved clients proactively adjust their request rate before actually hitting the limit and receiving a rejected request.
if ($requestCount > $rateLimit) {
http_response_code(429);
header('Retry-After: 60');
echo json_encode(['error' => 'Rate limit exceeded']);
}
Real-world example
A public API implements rate limiting that allows one hundred requests per minute per API key, returning a clear 429 status code along with a Retry-After header whenever a client exceeds that limit, letting well behaved client applications adjust their behavior accordingly.
Common follow-ups: What algorithms are commonly used to implement rate limiting, such as token bucket or sliding window?;How do you communicate remaining rate limit quota to clients through response headers?
Security;Caching Strategies in PHP
How should a RESTful API handle versioning as its design evolves over time, and what are the tradeoffs between common approaches like URL based versioning and header based versioning?
Advanced
URL based versioning, such as including a version number directly in the path like slash api slash v2 slash products, is simple and highly visible but means every version essentially lives at a different URL, while header based versioning, using a custom request header to specify the desired version, keeps URLs cleaner and more stable over time but is less discoverable and requires clients to correctly set that header on every request, meaning the right choice often depends on your specific API consumers' needs and how frequently you anticipate needing breaking changes.
GET /api/v2/products
// Alternative header based approach
// GET /api/products
// Accept: application/vnd.myapi.v2+json
Real-world example
A public API initially launches with URL based versioning for its simplicity and clear visibility, giving external developers immediate, unambiguous confidence about exactly which version of the API their integration is calling.
Common follow-ups: How do you handle a breaking change to an API without disrupting existing clients still using an older version?;How long should an API typically continue supporting an older version after releasing a new one?
Routing & Middleware;Deployment & Hosting for PHP Applications
How should a RESTful API be designed to handle complex error responses consistently, including validation errors affecting multiple fields at once?
Advanced
A well designed API typically returns a consistent, structured error response format for every type of failure, including a clear top level error message along with, for validation failures specifically, a detailed breakdown identifying exactly which individual fields failed validation and why, all using an appropriate HTTP status code, which lets client applications programmatically handle errors consistently across every single endpoint rather than needing custom error parsing logic for each different API operation.
http_response_code(422);
echo json_encode([
'message' => 'Validation failed',
'errors' => ['email' => ['The email field is required'], 'age' => ['The age must be at least 18']]
]);
Real-world example
A registration API returns a consistently structured 422 response listing every specific validation failure across multiple fields at once, letting the client application display all relevant error messages to the user in a single pass rather than requiring several separate round trips to discover each individual validation issue.
Common follow-ups: What HTTP status code is most appropriate specifically for validation errors, as opposed to other types of client errors?;How do you design this consistent error format to remain useful across many different, unrelated types of API failures?
Form Handling & Validation;JSON Handling in PHP