Output

A PHP application sends a response in two steps: it writes the status line and the headers, and then it writes the body. Output performs both steps for a PSR-7 response, so your code only has to create the response. It is the last step of a web request and the entry point for custom output, for example a streamed file.

Minimal Setup

Create an Output and pass a response to respond(). With no argument, the body is written to php://output:

use Windwalker\Http\Output\Output;
use Windwalker\Http\Response\JsonResponse;

$output = new Output();

$output->respond(new JsonResponse(['status' => 'ok']));

Showcase

This example sends a file as a download. It uses StreamOutput for the body, so large files are not loaded into memory:

use Windwalker\Http\Output\StreamOutput;
use Windwalker\Http\Response\AttachmentResponse;
use Windwalker\Stream\Stream;

$file = new Stream(fopen('/var/exports/report.csv', 'r'));

$response = new AttachmentResponse(
    $file,
    200,
    [
        'Content-Type' => 'text/csv',
        'Content-Disposition' => 'attachment; filename="report.csv"',
    ],
);

$output = new StreamOutput();
$output->setMaxBufferLength(8192);

$output->respond($response);

The body is read from the stream in chunks of 8192 bytes, so large files are not loaded into memory at once.

Output Types

Output writes the status line, the headers, and the body. It accepts a stream or a path as the target. Use a stream other than php://output, for example a memory buffer in a test:

$output = new Output('php://memory');

NoHeaderOutput writes only the body. Use it in console commands or tests where the headers should not be sent:

use Windwalker\Http\Output\NoHeaderOutput;
use Windwalker\Http\Response\TextResponse;

$output = new NoHeaderOutput();
$output->respond(new TextResponse('done'));

StreamOutput writes the body in chunks. Set the chunk size with setMaxBufferLength(). When the response has a Content-Range header, StreamOutput writes only the requested range, which supports resumable downloads. Use setDelay() to pause between chunks.

CallbackResponse lets the response write its own body through the output object, as shown on the Messages page.

Headers and Output Order

respond() sends the status line and headers only if they have not been sent yet, and then sends the body. The check uses headersSent().

WARNING

Any output written before respond() sends the body first, for example an echo, a PHP warning, or a blank line after a closing ?> in an included file. After that, the headers cannot be sent, so the status and content type of the response are lost. Do not write to php://output directly while you use Output.