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    <p>GearHead is correct, except that the jQuery parser is actually smart enough now to treat an empty string response as null and not attempt to parse it.</p> <p>However if you have calls that will sometimes receive json and sometimes receive a <code>head</code> response, and you do not have access to the server or do not want to change all your <code>head</code> calls, you can do this alternate solution:</p> <p>The problem is that Rails sends a single space as an empty response when you use <code>head</code> (see here: <a href="https://stackoverflow.com/questions/3351247/how-to-return-truly-empty-body-in-rails-i-e-content-length-0">How to return truly empty body in rails? i.e. content-length 0</a>)</p> <p>The relevant parts of the jQuery parseJSON function look like this at the time of this writing:</p> <pre><code>parseJSON: function( data ) { if ( typeof data !== "string" || !data ) { return null; } // Make sure leading/trailing whitespace is removed (IE can't handle it) data = jQuery.trim( data ); // Attempt to parse using the native JSON parser first if ( window.JSON &amp;&amp; window.JSON.parse ) { return window.JSON.parse( data ); } </code></pre> <p>As you can see, jQuery is testing whether the data is an empty string <em>before</em> trimming it. It then tries to <code>JSON.parse("")</code> which you can see in your console results in an error, triggering the ajax error callback via a <code>catch</code> statement.</p> <p>There is a simple fix. jQuery allows you to use converters when one data type is requested and a different one is returned. See here for more details: <a href="http://api.jquery.com/extending-ajax/" rel="nofollow noreferrer">http://api.jquery.com/extending-ajax/</a></p> <p>Since the rails <code>head</code> response renders as text, you can simply define a text to json converter that will trim the response prior to attempting to parse it. Just add this snippet:</p> <pre><code>// deal with rails ' ' empty response jQuery.ajaxSetup({ converters: { "text json": function (response) { jQuery.parseJSON($.trim(response)) } } }) </code></pre>
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Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

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