title: Symfony form Set Value of non mapped field from database
body: <p>I have a TextType <strong>label</strong> field in my form, my Entity is EAV, 
  the structure is : 
  id, 
  targetId,
  entityTargetName,</p>
  
  <p>In my form I have a non mapped field <strong>label</strong> a dynamic  from database,  when rendering my form I must send a query to database with targetId and entityTargetName and get the value of <strong>label</strong> field and set it to the form.</p>
  
  <p>I know that I can do query builder but my field is not a select, it's a TexType </p>
  
  <pre><code>        -&gt;add('productName ', TextType::class,
              array(
                  'mapped'=&gt;false,
              )
          )
  </code></pre>
  
  <p>Any idea ? </p>