title: Query Picasa Web Albums for specific PhotoIDs to check for existence
body: <p>I have a list of PhotoIDs as well as the User ID which apparently is required as PhotoID is not globally unique, and I'm attempting to get a list of photos in order to test whether the photos are still accessible.</p>
  
  <p>The closest I've found so far is here <a href="https://groups.google.com/forum/?fromgroups=#!searchin/google-picasa-data-api/photos" rel="nofollow">https://groups.google.com/forum/?fromgroups=#!searchin/google-picasa-data-api/photos</a>$20by$20id/google-picasa-data-api/OzLyJOVpd4M/7xiSPB4Tg9YJ which mentions the following query should get me there:</p>
  
  <pre><code>http://picasaweb.google.com/data/feed/api/user/default/?kind=photo&amp;v=2&amp;fields=entry[gphoto:id=1234 or gphoto:id=4567]&amp;prettyprint=true
  </code></pre>
  
  <p>However this doesn't appear to work, even when used with photos I know to exist, I either get:</p>
  
  <pre><code>&lt;?xml version='1.0' encoding='UTF-8'?&gt;
  &lt;feed xmlns='http://www.w3.org/2005/Atom' xmlns:app='http://www.w3.org/2007/app' xmlns:gphoto='http://schemas.google.com/photos/2007' xmlns:media='http://search.yahoo.com/mrss/' xmlns:gd='http://schemas.google.com/g/2005'/&gt;
  </code></pre>
  
  <p>Or if I specify a valid access_token I get the following, despite the token working fine for more basic queries of unlisted photos.</p>
  
  <pre><code>Token invalid - AuthSub token has wrong scope
  </code></pre>
  
  <p><strong>UPDATE</strong></p>
  
  <p>I've managed to get querying single gphoto:id work using the following:</p>
  
  <pre><code>https://picasaweb.google.com/data/feed/api/user/default?kind=photo&amp;v=2.0&amp;fields=entry[gphoto:id=5833637579580309538]
  </code></pre>
  
  <p>However as soon as I attempt to use <code>||</code> (as suggested below) I get an error such as:</p>
  
  <pre><code>Invalid selector expression at position 35: no viable alternative at character '|'  
  </code></pre>
  
  <p>If I use " or " as alluded to in the Google API Documentation, it simply ignores all but the first <code>gphoto:id</code> return only 1 row.</p>
  
  <p><strong>UPDATE 2</strong></p>
  
  <p>Actually it looks like the following DOES work, however not for all photos:</p>
  
  <pre><code>https://picasaweb.google.com/data/feed/api/user/default?kind=photo&amp;v=2.0&amp;fields=entry[gphoto:id=5827988830283069682%20or%20gphoto:id=5812362364496750642](gphoto:id)&amp;prettyprint=true
  </code></pre>
  
  <p>Is there some sort of permissioning that prevents some photos from being directly query-able?</p>