Can't write values of a form to file

Question

I have a form. Something like this:

Code:

    <form action="rewrite.php" method="get">
<?php 
    foreach ($tomb2[1] as $key => $metaname){
        $talalat = $tomb[1][$key]; 
        echo '<p>' . "$metaname\n" . '</p>' . '<br>' . '<input type="text" name="metavalue[]" value="' . "$talalat\n" . '">' . '<br>';
    }
?>    
<input type="submit" name="Generálás" value="insert" onclick="insert()" />
</form>

The values of the form are needed to be written to an xml file:

<property fmtid="{D5CDD505-2E9C-101B-9397-08002B2CF9AE}" pid="2" name="ALALALAL">4
</property>
<property fmtid="{D5CDD505-2E9C-101B-9397-08002B2CF9AE}" pid="3" name="MACABSZ">4
</property>
<property fmtid="{D5CDD505-2E9C-101B-9397-08002B2CF9AE}" pid="4" name="3">4
</property
><property fmtid="{D5CDD505-2E9C-101B-9397-08002B2CF9AE}" pid="5" name="4">4</property></Properties>

To the replace I use the following php code:

<?php 
$ertekek = $_GET["metavalue"];
 foreach ($ertekek as $alma ){
$rewrite= file_get_contents('docs/sablonTeszt20150805/docProps/custom.xml');
$rewrite = preg_replace('_<vt:lpwstr>(.*?)</vt:lpwstr>_', "$alma\n" , $rewrite);
file_put_contents('docs/sablonTeszt20150805/docProps/custom.xml', $rewrite );
 }
 ?>

The code is working, however only the last value of the form is written to the xml file. I need the following xml:

 <property fmtid="{D5CDD505-2E9C-101B-9397-08002B2CF9AE}" pid="2" name="ALALALAL">1
    </property>
    <property fmtid="{D5CDD505-2E9C-101B-9397-08002B2CF9AE}" pid="3" name="MACABSZ">2
    </property>
    <property fmtid="{D5CDD505-2E9C-101B-9397-08002B2CF9AE}" pid="4" name="3">3
    </property
    ><property fmtid="{D5CDD505-2E9C-101B-9397-08002B2CF9AE}" pid="5" name="4">4</property></Properties>

What am I doing wrong?

Answer 1

The preg_replace function by default replaces all matches of the regular expression. Therefore after the first iteration, there are no more <vt:lpwstr> tags in your XML , and so any following iteration will not have any matches, and will not change the XML any more.

The basic fix is using the optional limit argument of preg_replace , and indicate you only want one replacement:

$rewrite = preg_replace('_<vt:lpwstr>(.*?)</vt:lpwstr>_',
                        "$alma\n", $rewrite, 1);

Now there are several small improvements you could make:

First, it is a waste of disk I/O to read and write the file in each iteration. Just do it once, outside the loop.

Secondly, you'll want to remove any white-space that would remain before and after the replaced value.

Putting that all together, you would get this:

$ertekek = $_GET["metavalue"];
$rewrite = file_get_contents('docs/sablonTeszt20150805/docProps/custom.xml');
foreach ($ertekek as $alma) {
    $rewrite = preg_replace('_\s*<vt:lpwstr>(.*?)</vt:lpwstr>\s*_', 
                            "$alma", $rewrite, 1);
}
file_put_contents('docs/sablonTeszt20150805/docProps/custom.xml', $rewrite);

There is a potential weakness still, in that this code relies on a certain order of the metavalues iterated. I am not sure this is guaranteed across all steps performed.

On a final note, regular expressions are not the ideal way to manipulate XML files. The DOMDocument class in php provides all you need to do that in a controlled way.