limit to only posts that are tagged using PHP

I am trying to only get the posts that are tagged on a tumblr blog. I can get each post depending on what type of post it is (regular, link, photo, etc) but instead, I want to get each post that has a certain tag on it. For example, only get the posts that are tagged 'file'

Here is my code so far:

<?php
    $xml = simplexml_load_file('http://stock开发者_如何学Clamp.tumblr.com/api/read');
    $posts = $xml->xpath("/tumblr/posts/post[@type='photo']");
    foreach($posts as $post) {  

        }
    ?>

    <ul>
        <li> <a href="<?php echo $post['url-with-slug']; ?>">Post 1(PHP should be here)</a></li>
    </ul>

and here is tumblrs API http://www.tumblr.com/docs/en/api/v2

---

First, you'll need to have your markup within the curly braces that belong to the foreach loop. Otherwise, the scope of the $post object you're referencing will not be available, and it give you an error.

This is what I came up with:

<ul>
<?php

$xml = simplexml_load_file('http://stocklamp.tumblr.com/api/read');
$posts = $xml->xpath("/tumblr/posts/post/tag/..");
foreach($posts as $post) {
    echo "
  <li>
   <a href='{$post['url-with-slug']}'>".($post->{'regular-title'}?$post->{'regular-title'}:$post->{'link-text'})."</a>
  </li>
";
}

?>
</ul>

And if you want to limit the tags matched, you can do the following:

<ul>
<?php

$xml = simplexml_load_file('http://stocklamp.tumblr.com/api/read');
$posts = $xml->xpath("/tumblr/posts/post/tag[contains(text(),'xml') or contains(text(),'php') or contains(text(),'firefox')]/..");
foreach($posts as $post) {
    echo "
  <li>
   <a href='{$post['url-with-slug']}'>".($post->{'regular-title'}?$post->{'regular-title'}:$post->{'link-text'})."</a>
  </li>
";
}

?>
</ul>

Of course, that's a little messy. I'm not necessarily an XPath guru, so there should be a cleaner way than that I would think.

And since I wasn't really digging on the ternary for the link text, or the fact I don't know if one or the other will always be available, this should be more descriptive with a fallback to the url.

<ul>
<?php

$xml = simplexml_load_file('http://stocklamp.tumblr.com/api/read');
$posts = $xml->xpath("/tumblr/posts/post/tag[contains(text(),'xml') or contains(text(),'php') or contains(text(),'firefox')]/..");
foreach($posts as $post) {
    if ($post->{'regular-title'}) {
        $slug = $post->{'regular-title'};
    } else if ($post->{'link-text'}) {
        $slug = $post->{'link-text'};
    } else {
        $slug = $post['url-with-slug'];
    }
    echo "
  <li>
   <a href='{$post['url-with-slug']}'>".$slug."</a>
  </li>
";
}

?>
</ul>

EDIT

And, you also might want to make a match of the entire text of the TAG element, so that you don't get matches on things like xml-is-for-noobs when you want xml tags only. contains() will match both, while the below will only match xml.

/tumblr/posts/post/tag[text() = 'xml']/..

So, according to your comment, if you're looking for posts tagged events but don't want to catch tags like bowling-events, prevents fun, other events, etc..., you would want to make the text() = 'events' match. On the other hand, if you DID want to match anything with events in the text of the TAG node, use the contains(text(), 'events') method.

EDIT 2

And if you're trying to limit the results, use position():

(/tumblr/posts/post/tag[text() = 'xml']/..)[position() <= 3]

Note, the example on my webpage does not include the text() match, since there are not enough entries to support a submatch and still be productive. However, that should work.

http://jfcoder.com/test/tumblrtest.php

The XPath selects all TAG elements that belong to a POST element, then selects the parent (..) of that TAG, which gives you a SimpleXML object containing the relevant POST elements you're looking for.

Then, it iterates over each element, printing the $post's information into a UL element.