When working with PHP, you may need to extract a preferred locale from an Accept-Language header. This guide explains the operation, shows what its arguments mean, and uses three separate examples to make the result easier to understand.
Locale::acceptFromHttp: Language header negotiation returns a locale candidate, not confirmation that the application supports that locale.
What Is Locale::acceptFromHttp in PHP?
Extract a preferred locale from an Accept-Language header. Language header negotiation returns a locale candidate, not confirmation that the application supports that locale.
Syntax:
Locale::acceptFromHttp(string $header): ?string
Parameters and return value: The signature above identifies the arguments and return type where the API has a single call. For topic guides, follow the sequence of calls in the examples. Always distinguish a returned value from an object or variable modified by reference.
Important: Do not trust an HTTP header as authorization, and select a supported locale before displaying localized content.
Example 1: Basic Usage
This example introduces the operation with a short and predictable input.
<?php
var_dump(Locale::acceptFromHttp("fr-CA,fr;q=0.9,en;q=0.5"));
The code focuses on the main operation. Language header negotiation returns a locale candidate, not confirmation that the application supports that locale.
Example 2: Another Case
Now compare a different input, locale, date, or option to see another part of the behavior.
<?php
var_dump(Locale::acceptFromHttp("en-US,en;q=0.8"));
What changes? Do not trust an HTTP header as authorization, and select a supported locale before displaying localized content.
Practical Example: Applying It in an Application
Use the following separate example as a starting point for a small application task. Check any extension or environment requirements below before running it.
<?php
$header = "de-DE,de;q=0.9,en;q=0.5";
$preferredLocale = Locale::acceptFromHttp($header);
$supportedLocales = ["en_US", "de_DE"];
$selectedLocale = in_array($preferredLocale, $supportedLocales, true) ? $preferredLocale : "en_US";
echo $selectedLocale;
The practical example demonstrates how to apply this operation to multiple values, a reusable task, or a validated input. Language header negotiation returns a locale candidate, not confirmation that the application supports that locale.
Important Behavior and Edge Cases
- Core behavior: Language header negotiation returns a locale candidate, not confirmation that the application supports that locale.
- Inputs and results: Do not trust an HTTP header as authorization, and select a supported locale before displaying localized content.
- Alternatives: Locale::lookup() negotiates among available locales; Locale::acceptFromHttp() only examines the header.
- Compatibility: The intl extension is required.
Comparison With Related Functions
| Function or Approach | When to Use It |
|---|---|
Locale::acceptFromHttp | Extract a preferred locale from an accept-language header. |
| Related PHP approach | Locale::lookup() negotiates among available locales; Locale::acceptFromHttp() only examines the header. |
Common Beginner Mistakes
| Mistake | Correct Approach |
|---|---|
| Using an incorrect input or option | Do not trust an HTTP header as authorization, and select a supported locale before displaying localized content. |
| Confusing this API with a related operation | Locale::lookup() negotiates among available locales; Locale::acceptFromHttp() only examines the header. |
| Assuming output is identical across environments | Check return values and required extensions or versions. The intl extension is required. |
Key Takeaways
- Locale::acceptFromHttp helps you extract a preferred locale from an Accept-Language header.
- Language header negotiation returns a locale candidate, not confirmation that the application supports that locale.
- Do not trust an HTTP header as authorization, and select a supported locale before displaying localized content.
Use Locale::acceptFromHttp when you need to extract a preferred locale from an Accept-Language header. Start with the first example, compare the second, and adapt the practical example to your inputs. Confirm the return value and environment requirements before adding it to production code.