Respond to approved browser origins explicitly when credentials are used and return Vary: Origin for cache correctness. The examples below demonstrate the main workflow, an edge case and one practical integration pattern.
What Does This Workflow Do?
Use the first example to see the core idea. The additional examples demonstrate validation and a separate integration scenario. Set timeouts, validate destinations, keep secrets out of logs and follow the protocol semantics for the chosen status code.
Syntax:
The complete workflow is demonstrated below; individual calls are explained in context.
Requirements and Data Flow
There is no single function signature for this workflow. The required variables depend on the request, server configuration and libraries used in the examples.
Example 1: Basic Usage
Respond to approved browser origins explicitly when credentials are used and return Vary: Origin for cache correctness.
<?php
$trustedOrigins = ["https://app.example.test"];
$requestOrigin = $_SERVER["HTTP_ORIGIN"] ?? "";
if (in_array($requestOrigin, $trustedOrigins, true)) { header("Access-Control-Allow-Origin: " . $requestOrigin); header("Vary: Origin"); header("Access-Control-Allow-Credentials: true"); }
This example demonstrates the central operation. The final output depends on the supplied input and, where relevant, the runtime or connected service.
Example 2: Handling a Different Case
<?php
$rawPage = "invalid";
$pageNumber = filter_var($rawPage, FILTER_VALIDATE_INT);
var_dump($pageNumber);
The second example focuses on a different input or failure condition, so the behavior can be distinguished from the basic case.
Practical Example
<?php
http_response_code(422);
header("Content-Type: application/problem+json");
echo json_encode(["type" => "about:blank", "title" => "Invalid request", "status" => 422], JSON_THROW_ON_ERROR);
The practical example demonstrates how the same subject fits into a larger application. Use your own file paths, endpoints and validated inputs rather than copying sample settings directly.
Important Behavior and Edge Cases
- Set timeouts, validate destinations, keep secrets out of logs and follow the protocol semantics for the chosen status code.
- Keep the example scoped to its stated purpose. A sample does not replace application authentication, authorization, production configuration or deployment review.
- Use the documented return type and handle false, null and exceptions according to the specific call.
Comparison With Related Functions
| Approach | Difference |
|---|---|
| Handling Cross-Origin Requests Without Wildcard Credentials | Respond to approved browser origins explicitly when credentials are used and return Vary: Origin for cache correctness. |
| Input validation | Checks whether values satisfy the application rules before being used. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Confusing input validation with output escaping | Validate against application rules and escape separately for the final HTML, JSON or URL context. |
| Treating a single control as complete security | Add authorization, safe storage, secure cookies and other required controls. |
| Copying sample input into production configuration | Use secrets management, environment configuration and meaningful error handling. |
Key Takeaways
- Set timeouts, validate destinations, keep secrets out of logs and follow the protocol semantics for the chosen status code.
- Keep the example scoped to its stated purpose. A sample does not replace application authentication, authorization, production configuration or deployment review.
- Use the documented return type and handle false, null and exceptions according to the specific call.
Respond to approved browser origins explicitly when credentials are used and return Vary: Origin for cache correctness. Use this approach when its capabilities and constraints match the application. Handle invalid data, failure conditions and resource cleanup explicitly.