How to create a calculated field that automatically updates when other fields change

Are you binding to this "Fullname" property? If so I'm having a hard time seeing all the need for all the code. putting AfterSet on the FirstName and LastName that raise the onpropertychanged("Fullname") would alert the UI to re-get Fullname. And of course if you are checking the object through code you will trigger the re-get every time you reference it.

Paul,

In the interim, I believe this code would also work for you. It implements the logic of setting the FullName in the getter of the FullName property which is equivalent to defining a BeforeGet property interceptor. This in turn avoids the need to construct and use a DataEntityProperty which causes the bug I mentioned earlier.

    public String FullName {
      get {
        string currentLastName = CurrentLastName;
        if (currentLastName.Length > 0) {
          _fullName = currentLastName + ", " + FirstNames;
        } else {
          _fullName = FirstNames;
        }
        return _fullName;
      }
      set { _fullName = value; }
    }
    private static String _fullName;

    [AfterSet(EntityPropertyNames.FirstName)]
    [AfterSet(EntityPropertyNames.LastName)]
    //[BeforeGet("FullName")]
    public void AfterChangeFirstOrLastName(PropertyInterceptorArgs<Person, String> args)
    {
      SetFullName();
    }

Yup, this is a bug. We will fix this in our next release. The fix will be to provide an additional constructor for DataEntityProperty with a flag that will allow you to specify whether or not this property is a native property (default=true). Therefore, for calculated properties you would set this flag to false in the constructor and this would guarantee that the entity state will not be set to modified if you call set on the calculated property.

Can we deduce from the fact that no replies are posted anymore to our question that it is not possible to create a calculated field the way we've programmed it without changing the Entity to state = modified?

The Problem for us is that after a load of the Person Entity (in this case) the BeforeGet is fired on the SetFullName which in turn changes the FullName Property which in turn sets the Entity to modified. FullName is only a calculated field and is never stored in the DB. Since we automatically save changes (without a save button being activated) we have gotten a performance problem. The Save takes 2 seconds (which is too long, but IdeaBlade is working on that) and we save when switching Tabs in a TabControl

Eileen,

Eileen,

Edited by Sinnema - 16-Jul-2009 at 2:58am

In the First Name / Last Name setters you should do this:

this.EntityAspect.ForcePropertyChanged(null);

It will cause all the calculated properties to be 'reset'