dev-notes/docs/php/psr-7.md

PSR-7

PSR-7

Standard of the PHP Framework Interop Group that defines common interfaces for handling HTTP messages.

• Psr\Http\Message\MessageInterface
• Psr\Http\Message\RequestInterface
• Psr\Http\Message\ResponseInterface
• Psr\Http\Message\ServerRequestInterface
• Psr\Http\Message\StreamInterface
• Psr\Http\Message\UploadedFileInterface
• Psr\Http\Message\UriInterface

Example:

// empty array if not found
$header = $request->getHeader('Accept');

// empty string if not found
$header = $request->getHeaderLine('Accept');

// check the presence of a header
if (! $request->hasHeader('Accept')) {}

// returns the parameters in a query string
$query = $request->getQueryParams();

Immutability

PSR-7 requests are immutable objects; a change in the data will return a new instance of the object. The stream objects of PSR-7 are not immutable.