Background task with Ajax

Tutorials

background, asynchronous, AJAX

// Returned from the form
if (isset($_POST['par'])) {
$par = $_POST['par']; // parameter specified
$fn = "rep_$par.txt"; // file name
$mime = 'text/plain'; // file type
$cont = $model->doTask($par); // generate reportlong report generation // Ajax button if (Yii::app()->request->isAjaxRequest) { $lt = new Longtask; $lt->cleanMy(); // deletes the previous task result
$lt->filename = $fn;
$lt->cont = $cont;### runTask form

This form contains one text field, a submit button and an ajaxSubmitButton. The same form contains also thea link to download the result of the executed background task:* The application administrator should have access to the `longtask` table in order to monitor all the background jobs.

* One can use also [`ajaxLink`](http://www.yiiframework.com/doc/api/1.1/CHtml#ajaxLink-detail) in case there are no input parameters requested from the user. * One can keep more records per task/user to preserve the history of tasks. In this case it is better for the user to have access to the `longtask` table via [`CGridView`](http://www.yiiframework.com/doc/api/1.1/CGridView).

* More information on the tasks can be specified in the `longtask` table. For example, it is possible to save the start time and the percentage of the execution. See for example the [BackJob extension](http://www.yiiframework.com/extension/backjob/).* When the task's result is downloaded, it is reasonable to automatically delete the task's record from the `longtask` table. When the user has downloaded/deleted from the `runTask` form, a javascript should immediately hide the download link.

* When the task takes very long time to execute, it is a good idea to add in the beginning of the task code the `set_time_limit()` PHP instruction.