致命错误：未捕获异常：FPDF 错误：一些数据已经是 output，无法发送 PDF 文件（输出开始于

Question

I am generating a PDF file based on the selected employee ID i was facing an error on the local system while still in development saying that Fatal error: Uncaught Exception: FPDF error: Some data has already been output, can't send PDF file (output started at the/path)

And then i added these two lines to the php script and it worked fine

ob_start();

and at the end

ob_end_flush();

But after hosting it to the live server the error is thrown again

Have reffered the FPDF documn** ob_end_clean(); ** on the beginning of the php script Documentation Link

The complete code for this is as follows,

The empleavehis.php page

<?php
if (isset($_POST['pdfemployeeleave'])) {
ob_start();
require('mysql_table.php');

$link = mysqli_connect('localhost','root','','hr');
$empidinfo=$_REQUEST['empid'];

class PDF extends PDF_MySQL_Table
{
    function Header()
    {
    // Title
        $this->Image('img/prudentialshippinglines.png',15,6,15);
        $this->SetFont('Arial','',18);
        $this->Cell(0,6,'Short Summary ',0,1,'C');
        $this->Cell(0,6,' ',0,1,'C');
        $this->SetFont('Arial','',15);
        $this->Cell(0,6,'History Of Leaves Taken By The Employee',0,1,'C');
        $this->Ln(10);
    // Ensure table header is printed
        parent::Header();
    }
}

// Connect to database

$pdf = new PDF('L','mm','A4');


//$pdf->AddPage();
// First table: output all columns
// $pdf->Table($link,'select * from employees where EMP_ID = 1');
$pdf->AddPage();
// Second table: specify 3 columns
$pdf->AddCol('Leave_Type',48,'Type');
$pdf->AddCol('LeaveSub_Type',48,'Sub Type');
$pdf->AddCol('Start',48,'Start');
$pdf->AddCol('End',48,'End');
$pdf->AddCol('Remarks',48,'Remarks');
$pdf->AddCol('Status',48,'Status');

$prop = array('HeaderColor'=>array(255,150,100),
    'color1'=>array(210,245,255),
    'color2'=>array(255,255,210),
    'padding'=>2);
$pdf->Table($link,"select Leave_Type,LeaveSub_Type,Start,End,Remarks,Status from holiday where EMP_ID = '".$empidinfo."'",$prop);
//$pdf->Image('img/male.png',10,10,-300);
$fileName = "Leave Summary Of - ".$row['Name'].".pdf";
$pdf->Output($fileName, 'D');
}
ob_end_flush();
?>

The mysql_table.php file

<?php
require('fpdf.php');

class PDF_MySQL_Table extends FPDF
{
    protected $ProcessingTable=false;
    protected $aCols=array();
    protected $TableX;
    protected $HeaderColor;
    protected $RowColors;
    protected $ColorIndex;

    function Header()
    {
    // Print the table header if necessary
        if($this->ProcessingTable)
            $this->TableHeader();
    }

    function TableHeader()
    {
        $this->SetFont('Arial','B',12);
        $this->SetX($this->TableX);
        $fill=!empty($this->HeaderColor);
        if($fill)
            $this->SetFillColor($this->HeaderColor[0],$this->HeaderColor[1],$this->HeaderColor[2]);
        foreach($this->aCols as $col)
            $this->Cell($col['w'],6,$col['c'],1,0,'C',$fill);
        $this->Ln();
    }

    function Row($data)
    {
        $this->SetX($this->TableX);
        $ci=$this->ColorIndex;
        $fill=!empty($this->RowColors[$ci]);
        if($fill)
            $this->SetFillColor($this->RowColors[$ci][0],$this->RowColors[$ci][1],$this->RowColors[$ci][2]);
        foreach($this->aCols as $col)
            $this->Cell($col['w'],5,$data[$col['f']],1,0,$col['a'],$fill);
        $this->Ln();
        $this->ColorIndex=1-$ci;
    }

    function CalcWidths($width, $align)
    {
    // Compute the widths of the columns
        $TableWidth=0;
        foreach($this->aCols as $i=>$col)
        {
            $w=$col['w'];
            if($w==-1)
                $w=$width/count($this->aCols);
            elseif(substr($w,-1)=='%')
                $w=$w/100*$width;
            $this->aCols[$i]['w']=$w;
            $TableWidth+=$w;
        }
    // Compute the abscissa of the table
        if($align=='C')
            $this->TableX=max(($this->w-$TableWidth)/2,0);
        elseif($align=='R')
            $this->TableX=max($this->w-$this->rMargin-$TableWidth,0);
        else
            $this->TableX=$this->lMargin;
    }

    function AddCol($field=-1, $width=-1, $caption='', $align='L')
    {
    // Add a column to the table
        if($field==-1)
            $field=count($this->aCols);
        $this->aCols[]=array('f'=>$field,'c'=>$caption,'w'=>$width,'a'=>$align);
    }
    function Table($link, $query, $prop=array())
        {
        // Execute query
        $res=mysqli_query($link,$query) or die('Error: '.mysqli_error($link)."<br>Query: $query");
        // Add all columns if none was specified
        if(count($this->aCols)==0)
        {
            $nb=mysqli_num_fields($res);
            for($i=0;$i<$nb;$i++)
                $this->AddCol();
        }
        // Retrieve column names when not specified
        foreach($this->aCols as $i=>$col)
        {
            if($col['c']=='')
            {
                if(is_string($col['f']))
                    $this->aCols[$i]['c']=ucfirst($col['f']);
                else
                    $this->aCols[$i]['c']=ucfirst(mysqli_fetch_field_direct($res,$col['f'])->name);
            }
        }
        // Handle properties
        if(!isset($prop['width']))
            $prop['width']=0;
        if($prop['width']==0)
            $prop['width']=$this->w-$this->lMargin-$this->rMargin;
        if(!isset($prop['align']))
            $prop['align']='C';
        if(!isset($prop['padding']))
            $prop['padding']=$this->cMargin;
        $cMargin=$this->cMargin;
        $this->cMargin=$prop['padding'];
        if(!isset($prop['HeaderColor']))
            $prop['HeaderColor']=array();
        $this->HeaderColor=$prop['HeaderColor'];
        if(!isset($prop['color1']))
            $prop['color1']=array();
        if(!isset($prop['color2']))
            $prop['color2']=array();
        $this->RowColors=array($prop['color1'],$prop['color2']);
        // Compute column widths
        $this->CalcWidths($prop['width'],$prop['align']);
        // Print header
        $this->TableHeader();
        // Print rows
        $this->SetFont('Arial','',11);
        $this->ColorIndex=0;
        $this->ProcessingTable=true;
        while($row=mysqli_fetch_array($res))
            $this->Row($row);
        $this->ProcessingTable=false;
        $this->cMargin=$cMargin;
        $this->aCols=array();
    }
    }
    ?>

As far as I have checked I have not left any whitespaces or word spaces and also have tried setting the following

ob_clean();
ob_end_flush(); 
ini_set("session.auto_start", 0);

Error Image

The files also doesn't contain BOM characters

Answer 1

I shifted the whole fpdf code to the top of the php document and now it is getting downloaded. No changes to the code were done