Question

I have a model like this defined…

public class Product{
  private long timestamp;
  // get/set follows...
}

The timestamp field is fine for the database, since I persist the data via JPA. However, in the JSP output, I don’t want to present the timestamp as long, I want to present it as a customized String. I would like to define the long/String conversion in a custom method.

I could convert the timestamp field to DateTime or something, but this is a general question – how is it possible to process model data without modifying the model itself, because it’s just for the view? I looked into Spring Conversion and Formatter SPIs, but that doesn’t seem to fit here (Formatter is mainly for user input, Conversion applies to the whole model and I just want to manipulate one field of the model).

I already thought of creating a new object just for the view, passing all the data from the database model and manipulate it there, but there must be a better solution…

EDIT

Some additonal code…here is my controller:

@RequestMapping(method=RequestMethod.GET, value="/")
public ModelAndView getAllProducts() {
    List<Product> products = daoReader.findAllProducts();

    ModelAndView mv = new ModelAndView("myproductview");
    mv.addObject("products", products);

    return mv;

And this is the JSP (simplified):

<c:forEach items="${products}" var="currentproduct">
        <tr>
            <td>${currentproduct.timestamp}</td>
            <td>${currentproduct.name}</td>
        </tr>
</c:forEach>

Answer 1

Spring views normally use getters and setters to access the data of a model. The best solution would be to provide a getter that formats the date or convert the long object to a Date object or some other required format. From the views, you then access this getter method.

EDIT

public class Product{
  private long timestamp;

  public Date getDate() {
        return new Date(timestamp);
  }
}

and from the view

<c:forEach items="${products}" var="currentproduct">
        <tr>
            <td>${currentproduct.date}</td>
            <td>${currentproduct.name}</td>
        </tr>
</c:forEach>