Vibrant discussion about CSLA .NET and using the framework to build great business applications.
Hi,
I have a BusinessObject called Scale having multiple properties of type Weight (e.g. ReferenceWeight, DisplayWeight, StandardWeight, etc.)
The Weight BusinessObject itself has a WeightUnit and a WeightValue.
Now I want to Create a BusinessRule calculating a DisplayWeight when the WeightUnit or the WeightValue of the ReferenceWeight is updated. The DisplayWeight shhould only be updated when a property of the ReferenceWeight has been changed. If the properties of other Weight properties are changed the rules needs not to be called (must not be called).
I tried to mark the Weight BusinessObject as child and call the rule in OnChildChange:
protected override void OnChildChanged(Csla.Core.ChildChangedEventArgs e) { base.OnChildChanged(e); BusinessRules.CheckRules(DisplayWeightProperty);}
But in this case the rules is executed each time when one of the weight property has been changed. Moreover because I'm changing the DisplayWeight (whichis a Wight itself) the rules is called recursively...
What is the best way to implement a Business rule which depends on the property of a property (a subproperty)?
Thanks
Kirby
Check the parameter e, you should be able to see which property changed.
Some investigations later...
e.ChildObject and the my ReferenceWeight are the same objects when a property on ReferenceWeight changes... So a simple reference comparison does the trick!
protected override void OnChildChanged(Csla.Core.ChildChangedEventArgs e){ base.OnChildChanged(e); if (e.ChildObject == this.CurrentScaleWeight && (e.PropertyChangedArgs.PropertyName == "Unit" || e.PropertyChangedArgs.PropertyName == "Value") ) { BusinessRules.CheckRules(CurrentScaleWeightProperty); }}
Andy - you were right with your answer of corse!
Cheers
in "Csla.Core.ChildChangedEventArgs e" I can see the name of tha parameter changed (on the child object). I my case I see that WeightUnit or WeightValue was changed but I do not know whether it was a WeightValue of DisplayWeight or ReferenceWeight! If can check the ChildObject on e but that also gives me just an Weight and I have no idea what kind of weight.
Any ideas?
I need to do a similar thing except my child property is a list.
In this case, PropertyChangedArgs is null in the ChildChangedEventArgs param. How can I easily find the property that matches the ChildObject that has changed?
Note that I am implementing this in my own BusinessBase class derived from Csla.BusinessBase. So I can't simply do something like e.ChildObject == this.CurrentScaleWeight, like this example.
Any suggestions would be greatly appreciated.