Custom component: Export items to CSV -> Changing searchbar causes a new download

Question

I would like to export all selected items from the items-view of my component.

To do so I modified my view and inserted a new button to the

JToolBarHelper::custom('items.exportcsv', 'download', '', 'COM_BESTIA_EXPORT', true);

I also modified the controller:

/**
 * exportcsv function.
 * 
 * @access public
 * @return void
 */
public function exportcsv()
{

    $jinput                 =           JFactory::getApplication()->input;
    $ids                    =           $jinput->get('cid', '', 'array');
    $modelitems     =           $this->getModel();

    $array                  =           array();

    foreach($ids as $id)
    {
        $item                           =   $modelitems->getItem($id);      
        $array[$item->id]['itemid'] =   $item->itemid;
    }

    $csv                                    =       ArrayHelper::exportArrayToCSV($array, "items-report");
    $this->setRedirect('index.php?option=bestia&view=items', false);        

}       

Now I created a function in a helper function to create the download:

/**
 * exportArrayToCSV function.
 * 
 * @access public
 * @static
 * @param mixed $array
 * @return void
 */
public static function exportArrayToCSV($array, $filename, $delimiter=";")
{
    $config                         =   JFactory::getConfig();
    $tmppath                        =   $config->get('tmp_path');

    $keys                           =   array_keys($array);

    if(is_dir($tmppath))
    {
        $filename                   =   "$filename.csv";
        $filepath                   =   "$tmppath/$filename";
        $file                       =   new SplFileObject($filepath, 'w');

        $file->fputcsv(array_keys($array[$keys[0]]),$delimiter);

        foreach ($array as $fields) 
        {
            $file->fputcsv($fields,$delimiter);
        }

        if(file_exists($filepath))
        {   
            header ( 'Content-Description: File Transfer' );
            header ( 'Content-Type: application/force-download' );
            header ( 'Content-Type: application/octet-stream' );
            header ( 'Content-Disposition: attachment; filename=' . $filename ); 
            header ( 'Expires: 0' );
            header ( 'Cache-Control: must-revalidate' );
            header ( 'Pragma: public' );
            header ( 'Content-Length: ' . filesize ($filepath) );
            ob_clean(); 
            flush();
                readfile ($filepath);
                unlink($filepath); 
            exit();
        }
        else                            return false;   
    }
    else                                return false;       
}

This also works fine.

But I am facing a strange behaviour: If I download a CSV and change the filter after downloading in the search bar like this:

The file is downloaded again.

I think the problem is somewhere around here:

            ob_clean(); 
            flush();
                readfile ($filepath);
                unlink($filepath); 
            exit();

But I do not know how to solve it.

Answer 1

This is because each search form change triggers form submit

So you need to return "task" field to it's default value, wich is empty by default

function submitForm(){ this.form.submit(); jQuery('input[name="task"]').val("");  }

Answer 2

Check if you have hidden field named task if not then add following:

<input type="hidden" value="" name="task">

Then change its value by editing on change event as follows:

onchange="submitForm();"

Then add following small script:

<script>
  function submitForm(){
    this.form.task = 'subcontroller.csvDownloadTask';
    this.form.submit();
    this.form.task = '';
  }
</script>

Answer 3

Alexandr's solution is not longer working in Joomla 4, my approach is now by using webassets manager to include the script: (default.php)

...
$wa = $this->document->getWebAssetManager();
$wa->addInlineScript("
    jQuery(document).ready(function(){
        jQuery('#toolbar-download').on('click', function(e){
            const taskField = document.querySelectorAll('[name=\"task\"]');
            taskField[0].value = '';
        });
    });");
...

In the HtmlView.php adding the Button as follows:

...
ToolbarHelper::custom('seasons.export', 'download', '', 'COM_YOURCOMPONENT_BTN_LABEL_EXPORT', true);
...

Please note that #toolbar-download is the ID of your Export / Download Button.

seasons.export is the method that should be called in your controller:

SeasonsController.php

...
public function export()
    {
        $ids = $this->input->get('cid', [], 'array');
        error_log(print_r($ids, true));
        $model = $this->getModel('seasons');
        $data  = $model->exportItems($ids);
        $separator = ",";
        $enclosure = "\"";
        $escape = "\\";
        $eol   = "\n";
        $filename = 'seasons.csv';
        $headers  = array_keys($data[0]);
        $output   = fopen('php://output', 'wb');
        fputcsv($output, $headers, $separator, $enclosure, $escape, $eol);
        foreach ($data as $row)
        {
            fputcsv($output, $row);
        }

        header('Content-Type: text/csv');
        header('Content-Disposition: attachment; filename="' . $filename . '"');
        fclose($output);

        exit;
    }
...

That way the download works and when changing afterwards the filter it won't trigger the download again.