Question

I have an input form with:

<s:form action="myaction" method="POST" enctype="multipart/form-data" >
   ...     
   <s:file label="Picture" name="img" /> 
   ...
   <s:submit value="Send" />
</s:form>

How can I return error if user don’t insert an image (it’s a required field)?
I’m using Hibernate validation (@NotEmpty, @NotNull, ecc..), but I don’t know if it’s possible validate a file input field.

Answer 1

You could validate File object for null with Struts2 required validator http://struts.apache.org/2.x/docs/required-validator.html.

Additionally @NotNull accepts any type, not only Strings http://docs.oracle.com/javaee/6/api/javax/validation/constraints/NotNull.html.