title: if statement in gridview template filed
body: <p>I have a gridview. its data source is a datatable that is loaded from the database.
  In this gridview, i have a template column. The content of this column is not directly pulled from the database but instead, i use the id of the current item to make a name and look for that name in a directory of images. The template field is:</p>
  
  <pre><code>&lt;asp:TemplateField&gt;
      &lt;itemtemplate&gt;
          &lt;img src='../user/images/&lt;% =itemType %&gt;&lt;%# DataBinder.Eval(Container.DataItem, "id") %&gt;.jpg?'
              alt='&lt;%# DataBinder.Eval(Container.DataItem, "Title") %&gt;' /&gt;
      &lt;/itemtemplate&gt;
  &lt;/asp:TemplateField&gt;
  </code></pre>
  
  <p>Not all the items have images so I would like to check if this file exists. If it does, I'd like to use the above code to place it, if it doesn't i'd like to leave the field empty.
  In the .cs file this is a matter of an if statement with the condition set to File.Exist(). But I could not find the syntax to do it in the .aspx file.
  Is this possible and if so how?
  Thanks.</p>