how to alter and then show attributes in html with php - php

Question

in my table, I have a row that contains a string like this:
<p>hello</p><p>this is patrick</p><p><img src="/assets/img/myface.jpg" width="320" height="320"/></p>
and I want to give the <img> tag an alt attribute. I've got quite close now but somehow my code still shows 2 <img> tags although the string only has 1. can anyone tell me what I'm doing wrong?
this is my code so far:
$str = '<p>hello</p><p>this is patrick</p><p><img src="/assets/img/myface.jpg" width="320" height="320"/></p>';
$new_html = '';
$dom = new DOMDocument();
$dom->loadHTML($str);
$content = $dom->getElementsByTagName('*');
foreach ($content as $i => $node)
{
if ($node->nodeName == 'html' || $node->nodeName == 'body')
{
continue; // dont need to process these tags, right?
}
if ($node->nodeName == 'img')
{
$img_src = $node->getAttribute('src');
$path_arr = explode('/', $img_src);
$filename = $path_arr[count($path_arr)-1]; // myface.jpg
$alt = 'blah';
$node->setAttribute('alt', $alt);
}
echo $dom->saveXML($node);
}

Answer 1

$content = $dom->getElementsByTagName('img');
foreach ($content as $node) {
$img_src = $node->getAttribute('src');
$filename = basename($img_src);
$node->setAttribute('alt', $filename);
}
echo $dom->saveHTML();
Loop only through images with $content = $dom->getElementsByTagName('img');
Move $dom->saveHTML(); after lthe loop.
Get filename with $filename = basename($img_src);

Answer 2

The slightly changed code below does the work. It only gets the img tags and saves the HTML outside the loop. Note that I changed the way that HTML was loaded, to not include the wrapper tags.
<?php
$str = '<p>hello</p><p>this is patrick</p><p><img src="/assets/img/myface.jpg" width="320" height="320"/></p>';
$new_html = '';
$dom = new DOMDocument();
$dom->loadHTML($str, LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD);
$content = $dom->getElementsByTagName('img');
foreach ($content as $i => $node)
{
$img_src = $node->getAttribute('src');
$path_arr = explode('/', $img_src);
$filename = $path_arr[count($path_arr)-1]; // myface.jpg
$alt = 'blah';
$node->setAttribute('alt', $alt);
}
echo $dom->saveHTML();

Answer 3

The problem is that when you use
echo $dom->saveXML($node);
in the loop, it will output for various tags and so the output is not the end result, but a combination of other parts of the document.
Try changing it to
echo $node->nodeName."=>".$dom->saveXML($node).PHP_EOL;
to see what it does.
You could just remove the current echo and add
echo $dom->saveXML();
after the end of the loop.
Alternatively, if you just want to process the <img> tags, you can limit the loop more specifically...
$content = $dom->getElementsByTagName('img');
foreach ($content as $i => $node)
{
$img_src = $node->getAttribute('src');
$path_arr = explode('/', $img_src);
$filename = $path_arr[count($path_arr)-1]; // myface.jpg
$alt = 'blah';
$node->setAttribute('alt', $alt);
}
echo $dom->saveXML();