title: React Admin: Can I use another field for <ReferenceInput>, other than "id"?
body: <p><strong>Is there any way to use a different reference field (other than <code>id</code>) for a <code>ReferenceInput</code>?</strong><br/></p>
  
  <p>For example:<br/>
  I have a <code>languages</code> resource, which I want to populate using a <code>language_code</code> field.<br/>Note, I don't want to use the <code>id</code> field of <code>languages</code>, I want to use the <code>code</code> field.<br/></p>
  
  <p>I have managed to get it to work by using the following:</p>
  
  <pre class="lang-js prettyprint-override"><code>&lt;ReferenceInput 
    label="Language code" 
    source="language_code" 
    reference="languages"
  &gt;
    &lt;SelectInput optionText="name" optionValue="code" /&gt;
  &lt;/ReferenceInput&gt;
  </code></pre>
  
  <p>The only problem with this is that:<br/> </p>
  
  <p>After selecting a language from the select input, the <code>ReferenceInput</code> tries to fetch the resource using the <code>code</code> field rather than the <code>id</code> field, which returns a 404 error.</p>