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Hello Koolreport,
I recently implemented PDF Export in one of my Yii2 based project.
I checked whole docs, examples as well as forum topics and I see I can't resolve this issue.
Kindly check images attached.
Here is the error log I see when open the PDF in Notepad++
An Error occurred while handling another error: yii\web\HeadersAlreadySentException: Headers already sent in D:\wamp\www\humhub\sw7_new\protected\modules\sw7reports\vendor\koolreport\export\File.php on line 67. in D:\wamp\www\humhub\sw7_new\protected\vendor\yiisoft\yii2\web\Response.php:373 Stack trace: #0 D:\wamp\www\humhub\sw7_new\protected\vendor\yiisoft\yii2\web\Response.php(346): yii\web\Response->sendHeaders() #1 D:\wamp\www\humhub\sw7_new\protected\vendor\yiisoft\yii2\web\ErrorHandler.php(136): yii\web\Response->send() #2 D:\wamp\www\humhub\sw7_new\protected\vendor\yiisoft\yii2\base\ErrorHandler.php(135): yii\web\ErrorHandler->ren
It meant your app already output some data (blank spaces, lines, error messages, etc) before the pdf data. Pls remove all blank spaces, lines after all PHP ending sequence ?> in your files. Another option is to use buffering and discard it right before pdf output. For example:
//export.php or export() method
ob_start();
$report = new MyReport();
$report->run();
$handler = $report->export(...)->pdf(...);
...
ob_end_clean();
$handler->toBrowser(...);
OK I tried this as well. and the same error there.
I check all my controllers, views, lalyouts etc. and there are no exra space character which may generate this error.
Error log when open PDF in notepad++
An Error occurred while handling another error: yii\web\HeadersAlreadySentException: Headers already sent in D:\wamp\www\humhub\sw7_new\protected\modules\sw7reports\vendor\koolreport\export\File.php on line 67. in D:\wamp\www\humhub\sw7_new\protected\vendor\yiisoft\yii2\web\Response.php:373 Stack trace: #0 D:\wamp\www\humhub\sw7_new\protected\vendor\yiisoft\yii2\web\Response.php(346): yii\web\Response->sendHeaders() #1 D:\wamp\www\humhub\sw7_new\protected\vendor\yiisoft\yii2\web\ErrorHandler.php(136): yii\web\Response->send() #2 D:\wamp\www\humhub\sw7_new\protected\vendor\yiisoft\yii2\base\ErrorHandler.php(135): yii\web\ErrorHandler->ren
And here is the error log
yii\base\InvalidArgumentException: Response content must be a string or an object implementing __toString(). in D:\wamp\www\humhub\sw7_new\protected\vendor\yiisoft\yii2\web\Response.php:1117 Stack trace: #0 D:\wamp\www\humhub\sw7_new\protected\vendor\yiisoft\yii2\web\Response.php(344): yii\web\Response->prepare() #1 D:\wamp\www\humhub\sw7_new\protected\vendor\yiisoft\yii2\base\Application.php(398): yii\web\Response->send() #2 D:\wamp\www\humhub\sw7_new\index.php(29): yii\base\Application->run() #3 {main}
One way to check the content of exporting is to do this:
Instead of calling:
$report->run()->export(..)->pdf(...)->toBrowser(..);
You do:
$report->run()->render();
It will render content to browser, you view the html content and see if any extra content (even a space) before the content of report. It may help to know where went wrong.
Well the export PDF functionality of Koolreport is not working as expected!
Finally I had used this module "https://github.com/kartik-v/yii2-mpdf" to sort this out.
I have a due date to finish this functionality in time (a lot of client's pressure) so I have to take another way with another Yii2 extension
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