Conditional send_headers

  • Hi all,

    I am trying to display a PDF file that has been stored in the database.
    If I use the following code it wants to display the PDF on every page:

    <?php
	global $wpdb;
//*******************************************************************************************************************************************

function viewPDF()
	{
		global $wpdb;
		global $FileContent;

		$mydataset = $wpdb->get_row("SELECT * FROM customTest_tbl WHERE ID = 28");

		$recordID = $mydataset->ID;
		$FileType = $mydataset->FileType;
		$FileSize = $mydataset->FileSize;
		$FileName = $mydataset->FileName;
		$FileContent = $mydataset->FileContent;

		header("Content-Type: ". $FileType);
		header("Content-Length: ". $FileSize);
		header("Content-Disposition: attachment; filename=". $FileName);

	}

add_action( 'send_headers', 'viewPDF' );

//*******************************************************************************************************************************************

    So obviously I would like to add an IF statement that will only run the function if the Page Title = ‘ViewPDF’.
    So I tried this code:

    <?php
	global $wpdb;
//*******************************************************************************************************************************************
	$MyTitle = get_the_title();

	function viewPDF()
	{
			global $wpdb;
			global $FileContent;

				$mydataset = $wpdb->get_row("SELECT * FROM em_purchaserequest_additionalinfo_tbl WHERE ID = 28");

				$recordID = $mydataset->ID;
				$FileType = $mydataset->FileType;
				$FileSize = $mydataset->FileSize;
				$FileName = $mydataset->FileName;
				$FileContent = $mydataset->FileContent;

				header("Content-Type: ". $FileType);
				header("Content-Length: ". $FileSize);
				header("Content-Disposition: attachment; filename=". $FileName);

	}

if ($MyTitle == 'ViewPDF')
{
	add_action( 'send_headers', 'viewPDF' );
}

//*******************************************************************************************************************************************
?>

    And also tried:

    <?php
	global $wpdb;
//*******************************************************************************************************************************************

	function viewPDF()
	{
			global $wpdb;
			global $FileContent;

			$MyTitle = get_the_title();

			if ($MyTitle == 'ViewPDF')
			{
				$mydataset = $wpdb->get_row("SELECT * FROM em_purchaserequest_additionalinfo_tbl WHERE ID = 28");

				$recordID = $mydataset->ID;
				$FileType = $mydataset->FileType;
				$FileSize = $mydataset->FileSize;
				$FileName = $mydataset->FileName;
				$FileContent = $mydataset->FileContent;

				header("Content-Type: ". $FileType);
				header("Content-Length: ". $FileSize);
				header("Content-Disposition: attachment; filename=". $FileName);
			}
	}

	add_action( 'send_headers', 'viewPDF' );

//*******************************************************************************************************************************************
?>

    But either two tries does not open the PDF file, only the first code, where there is no IF statement.
    I also have checked and confirmed that $MyTitle = get_the_title(); really is = ‘ViewPDF’
    Can anyone please help point out my mistake?

    Thank you so much!!

Viewing 7 replies - 1 through 7 (of 7 total)

  • My guess: To call get_the_title() you need the $post object not the database object $wpdb.

    global $post;

$MyTitle = get_the_title( $post->ID );

if( $MyTitle === 'ViewPDF' ) {

	add_action( 'send_headers', 'viewPDF' );

}

    Another guess^^ The sent_headers hook is being executed before the post is even being loaded. Therefore, at the time when your function is running there won’t be a post (title) available yet.

    A bit dirty, but what you might do is to hook into the redirect hook, for example. Then, in your function, check for the proper title and if the title is right not only set the headers but also do the output.

    add_action( 'template_redirect', 'viewPDF' );

function viewPDF()
{

  global $post;
  global $wpdb;
  global $FileContent;

  $MyTitle = get_the_title( $post->ID );

  if ( $MyTitle !== 'viewPDF' )
  {
    return;
  }

  mydataset = $wpdb->get_row("SELECT * FROM em_purchaserequest_additionalinfo_tbl WHERE ID = 28");

  $recordID = $mydataset->ID;
  $FileType = $mydataset->FileType;
  $FileSize = $mydataset->FileSize;
  $FileName = $mydataset->FileName;
  $FileContent = $mydataset->FileContent;

  header("Content-Type: ". $FileType);
  header("Content-Length: ". $FileSize);
  header("Content-Disposition: attachment; filename=". $FileName);

  // eg readfile( $File ) or whatever your file is

  exit;

}
    Thread Starter A31

    (@a31)

    Hi Chris,

    Your last post helped a lot and it is working! Thank You!!

    Can you perhaps help with the next phase?

    How do I pass a variable into that function from another form?

    I need to set the WHERE conditions (ID) of the document that needs to be displayed.

    How do you get the ID? Is it being sent via the form or do you detect it after the form has been send and according to the submitted data?

    Thread Starter A31

    (@a31)

    Preferably it is sent from a form.

    The user selects the document he /she wishes to view, that then sends the ID of the doc and is then displayed.

    Hope that makes sense?

    Thread Starter A31

    (@a31)

    What i have done now, is to write a unique string into the database when the user clicks view for a specific document, then redirects to the ViewPDF page, and there pull from the database the criteria.

    This does work, but seems like a long long way around just to pass a variable?

    It is. I would stick with sending the ID along with the form data. Then you could simply check $_GET or $_POST (depending which method you’re using to send the form).

    ...

  $uid = ( isset( $_GET['uid'] ) ) ? (int) $_GET['uid'] : 0;
  // Or $_POST depending on how you're sending the form and what the name for the ID parameter is.
  // When you do a redirect to /ViewPDF/ just add the ID as parameter /ViewPDF/?uid=123 and you can check $_GET

  if ( $uid < 1 )
  {
    // Error handling: Missing or invalid parameter
  }

  // Always treat external inputs as potentially harmful and add another layer of security by "preparing" db queries
  $query      = $wpdb->prepare( "SELECT * FROM em_purchaserequest_additionalinfo_tbl WHERE ID = %d", $uid );

  $mydataset  = $wpdb->get_row( $query );

  if ( $mydataset === null )
  {
    // Error handling: The query is valid and has been secured but the ID simply does not exist
  }

  $recordID = $mydataset->ID;
  ...
Viewing 7 replies - 1 through 7 (of 7 total)
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