title: How to get only one argument value sent as JSON
body: <p>my link to my web page is like this</p>
  
  <blockquote>
    <p><code>http://mysite.php?json={"some_key":"some_val"}</code></p>
  </blockquote>
  
  <pre><code>$json=$_GET ['json'];  
  $obj = json_decode($json);
  #this line print the whole input 
  echo $json."&lt;/br&gt;";
  
  #but this does not print anythig 
  echo $obj-&gt;{'some_key'}."&lt;/br&gt;";
  </code></pre>
  
  <p>I am new to php and I get stuck in the reading input... :(</p>
  
  <p>**edit</p>
  
  <p>My point is to take the some_val into variable so I can make decisions according the value...</p>
  
  <p>For me is the easiest way to put it in the url, but if I have to I will implement POST method.</p>
  
  <p>The code I need should look like this</p>
  
  <blockquote>
    <p>$variable=(read the value for the key "some_key")</p>
  </blockquote>