title: Ext JS 4.1.3: How to get a value from a JSON store
body: <p>I have a <code>Ext.data.Store</code> filled with language variables. The JSON behind looks like this:</p>
  
  <pre><code>{
      "language":"en_GB",
      "data":[
          {"fieldName":"browserInfo","fieldValue":"Descriptive text"}
      ]
  }
  </code></pre>
  
  <p>The store I have created:</p>
  
  <pre><code> Ext.local.langStore = Ext.create('Ext.data.Store', {
       autoLoad: true,
       fields: [
           {name: 'fieldName', type: 'string'},
           {name: 'fieldValue', type: 'string'},
       ],
       proxy: {
           type: 'ajax',
           url: 'en_GB.json',
           reader: {
               type: 'json',
               root: 'data'
           }
       }
   });
  </code></pre>
  
  <p>I'm trying to get the <code>fieldValue</code> from the given <code>fieldName</code>. How do I do this in Ext? I have tried using: </p>
  
  <pre><code>var getLabel = function(field_id) {
      var store = Ext.local.langStore;
      var index = store.findExact('fieldName',field_id);
      if(index &gt;= 0) {
          return store.getAt(index).get('fieldValue'); 
      } else {
          return field_id;
      }
  }
  </code></pre>
  
  <p>But have not had much luck with it. <code>index</code> is always <code>-1</code></p>
  
  <p>Any help appreciated,</p>