How do I use StreamedResponse to render template view in Symfony2 - php

Question

I am trying to use streamedResponse to output progress to my index page in Symfony2.
This code below does show my progress on the api calls as it occurs, but I am having trouble rendering the streamed information in an actual view. Right now it is just outputing plain text on the top of the page, then rendering the view when its all complete.
I don't want to return the final array and close the function until everything is loaded, but I can't seem to get a regular twig template to show while I output the progress.
I have tried using render but nothing seems to truly ouput that view file to the screen unless I return.
public function indexAction($countryCode)
{
//anywhere from five to fifteen api calls are going to take place
foreach ($Widgets as $Widget) {
$response = new StreamedResponse();
$curlerUrl = $Widget->getApiUrl()
. '?action=returnWidgets'
. '&data=' . urlencode(serialize(array(
'countryCode' => $countryCode
)));
$requestStartTime = microtime(true);
$curler = $this->get('curler')->curlAUrl($curlerUrl);
$curlResult = json_decode($curler['body'], true);
if(isset($curlResult['data'])){
//do some processing on the data
}
$response->setCallback(function() use ($Widget, $executionTime) {
flush();
sleep(1);
var_dump($Widget->getName());
var_dump($executionTime);
flush();
});
$response->send();
}
//rest of indexAction with a return statement
return array(
//all the vars my template will need
);
}
Also, another important detail is that I am trying to render all to twig and there seems to be some interesting issues with that.

Answer 1

As I understand it, you only get one chance to output something to the browser from the server (PHP/Twig), then it's up to JavaScript to make any further changes (like update a progress bar).
I'd recommend using multi-cURL to perform all 15 requests asynchronously. This effectively makes the total request time equal to the slowest request so you can serve your page much faster and maybe eliminate the need for the progress bar.
// Create the multiple cURL handle
$mh = curl_multi_init();
$handles = array();
$responses = array();
// Create and add the cURL handles to the $mh
foreach($widgets as $widget) {
$ch = $curler->getHandle($widget->getURL()); // Code that returns a cURL handle
$handles[] = $ch;
curl_multi_add_handle($mh, $ch);
}
// Execute the requests
do {
curl_multi_exec($mh, $running);
curl_multi_select($mh);
} while ($running > 0);
// Get the request content
foreach($handles as $handle) {
$responses[] = curl_multi_getcontent($handle);
// Close the handles
curl_close($handle);
}
curl_multi_close();
// Do something with the responses
// ...
Ideally, this would be a method of your Curler service.
public function processHandles(array $widgets)
{
// most of the above
return $responses;
}

Answer 2

You may implements all of the logic in the setCallback method, so consider this code:
public function indexAction($countryCode)
{
$Widgets = [];
$response = new StreamedResponse();
$curlerService = $this->get('curler');
$response->setCallback(function() use ($Widgets, $curlerService, $countryCode) {
foreach ($Widgets as $Widget) {
$curlerUrl = $Widget->getApiUrl()
. '?action=returnWidgets'
. '&data=' . urlencode(serialize(array(
'countryCode' => $countryCode
)));
$requestStartTime = microtime(true);
$curler = $curlerService->curlAUrl($curlerUrl);
$curlResult = json_decode($curler['body'], true);
if(isset($curlResult['data'])){
//do some processing on the data
}
flush();
sleep(1);
var_dump($Widget->getName());
var_dump( (microtime(true) - $requestStartTime) );
flush();
}
});
// Directly return the streamed response object
return $response;
}
Further reading this and this article.
Hope this help