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POExtracting specific value from JSON string with PHP
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copied!<p>So I have what appears to be a pretty simple problem, though for the life of me with my lack of coding knowledge I can't figure it out. Excuse any misnomers! So I have a URL heading to a page which contains a signed request with a JSON string in it (it's a Facebook page). I need to retrieve that JSON string and then extract out just a specific part of it. I have no control over the formatting of the URL at the moment.</p> <p>On the page that it goes to I have the following code: </p> <pre><code><?php $signed_request = $_REQUEST['signed_request']; // Get the POST signed_request variable. if(isset($signed_request)) // Determine if signed_request is blank. { $pre = explode('.',$signed_request); // Get the part of the signed_request we need. $json = base64_decode($pre['1']); // Base64 Decode signed_request making it JSON. $obj = json_decode($json,true); // Split the JSON into arrays. echo $obj['app_data']; } else { die('No signed request avaliable.'); //If there is no signed_request, stop processing script. } ?> </code></pre> <p>That works fine, and echo $obj['app_data']; prints: {q:"id_src=abc123456789",}</p> <p>To me, that in itself is a JSON string, so I thought I could run a json_decode on that and then print out id_src=abc123456789. I tried that like this:</p> <pre><code>$appdata = $obj['app_data']; $idcode = json_decode($appdata,true); </code></pre> <p>Followed by echo $idcode['q'], but that just prints a single curly bracket. I tried various variations, removal of ' ' marks, removal of true, etc.</p> <p>My end goal is to just extract the abc123456789 value, not the id_src part. I figured it was probably faster to just ask since I'm unlikely to figure it out in the next few days.</p> <p>Thanks for the help all!</p> <p>EDIT: Snippet of $json added. echo $json; prints the following</p> <pre><code>{"algorithm":"HMAC-SHA256","app_data":"{q:\"id_src=abc123456789\",}","issued_at":1333500860,"page":{"id":"380641958713853","liked":false,"admin":true},"user":{"country":"nz","locale":"en_GB","age":{"min":21}}} </code></pre> <p>Would it be the comma after the id_src value that is causing problems?</p>

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