TCPDF ERROR: Some data has already been output, can't send PDF file

问题

I keep receiving this error when trying to add my own array into the code. Here is my array;

$array = array();

while (odbc_fetch_row($rs))
{
$array[] = odbc_result($rs,'Product Name');
} 
$test = print_r($array);

The original code is here. I'm using an example page to try it because I know the example page works fine.

http://www.tcpdf.org/examples/example_001.phps

This code is before the $html variable and when it is set I just add the $test variable into the $html variable. The odbc connection works fine and the example works fine before I add any code but when I run the script I get this error;

Array ( [0] => Test1 [1] => Test2 ) TCPDF ERROR: Some data has already been output, can't send PDF file

And there is also more than 2 items in the Array. Any ideas?

回答1:

Just use ob_start(); at the top of the page.

回答2:

Add the function ob_end_clean(); before call the Output function. It worked for me within a custom Wordpress function!

ob_end_clean();
$pdf->Output($pdf_name, 'I');

回答3:

Add the function ob_end_clean() before call the Output function.

回答4:

This problem means you have headers. Deletes tags

?>

at the end of your code and make sure not to have whitespace at the beginning.

回答5:

I just want to add that I was getting this error, and nothing would fix it until I changed the Output destination parameter from F to FI. In other words, I have to output to both file and inline.

Output('doc.pdf', 'I')

Output('doc.pdf', 'FI')

I have no idea why this made the difference, but it fixed the error for me...

回答6:

The tcpdf file that causes the "data has already been output" is in the tcpdf folder called tcpdf.php. You can modify it:

add the line ob_end_clean(); as below (3rd last line):

public function Output($name='doc.pdf', $dest='I') {
    //LOTS OF CODE HERE....}
    switch($dest) {
        case 'I': {
        // Send PDF to the standard output
        if (ob_get_contents()) {
        $this->Error('Some data has already been output, can\'t send PDF file');}
        //some code here....}
            case 'D': {         // download PDF as file
        if (ob_get_contents()) {
    $this->Error('Some data has already been output, can\'t send PDF file');}
            break;}
        case 'F':
        case 'FI':
        case 'FD': {
            // save PDF to a local file
                 //LOTS OF CODE HERE.....       break;}
        case 'E': {
            // return PDF as base64 mime email attachment)
        case 'S': {
            // returns PDF as a string
            return $this->getBuffer();
        }
        default: {
            $this->Error('Incorrect output destination: '.$dest);
        }
    }
           ob_end_clean(); //add this line here 
    return '';
}

Now lets look at your code.
I see you have $rs and $sql mixed up. These are 2 different things working together.

$conn=odbc_connect('northwind','****','*****');
if (!$conn) {
   exit("Connection Failed: " . $conn);
 }

$sql="SELECT * FROM products"; //is products your table name?
$rs=odbc_exec($conn,$sql);
if (!$rs) {
  exit("Error in SQL");
}

while (odbc_fetch_row($rs)) {
  $prodname=odbc_result($rs,"Product Name"); //but preferably never use spaces for table names.
 $prodid=odbc_result($rs,"ProdID");  //prodID is assumed attribute
  echo "$prodname";
  echo "$prodid";
}
odbc_close($conn);

now you can use the $prodname and output it to the TCPDF output.

and I assume your are connecting to a MS access database.

回答7:

use ob_end_clean();

$pdf->Output($file, 'I'); to open pdf. It works for me

回答8:

for my case Footer method was having malformed html code (missing td) causing error on osx.

public function Footer() {
$this->SetY(-40);
$html = <<<EOD
<table>
<tr>
 Test Data
</tr>
</table>
EOD;
$this->writeHTML($html);
}

回答9:

I had this but unlike the OP I couldn't see any output before the TCPDF error message.

Turns out there was a UTF8 BOM (byte-order-mark) at the very start of my script, before the <?php tag so before I had any chance to call ob_start(). And there was also a UTF8 BOM before the TCPDF error message.

回答10:

This problem is when apache/php show errors.

This data(html) destroy pdf output.

You must off display errors in php.ini.

回答11:

I had this weird error and the culprit is a white space on the beginning of the PHP open tag

even without the ob_flush and ob_end_clean

Just make sure there are no extra white spaces on or after any <?php ?> block

回答12:

Use ob_start(); at the beginning of your code.

回答13:

For those who are still facing this issue try adding:

libxml_use_internal_errors(true);

before the loadHtml call and add

libxml_use_internal_errors(false);

after the call.

This solved it for me.

回答14:

I had the same error but finally I solved it by suppressing PHP errors Just put this code error_reporting(0); at the top of your print page

    <?php 
    error_reporting(0); //hide php errors
    if( ! defined('BASEPATH')) exit('No direct script access allowed');
    require_once dirname(__FILE__) . '/tohtml/tcpdf/tcpdf.php';
    .... //continue

来源：https://stackoverflow.com/questions/16011050/tcpdf-error-some-data-has-already-been-output-cant-send-pdf-file

标签

php

tcpdf