Entity Framework - Custom logic in property setter

Question

Using an EF, Code First. In my class I have properties Quantity, Price and Amount. In setters of the first 2 properties I want to add logic to calculate amount. This works ok, but when I load entity next time, and Entity Framework fills properties with database values, than this custom logic is implemented too - and this is not good. How do you think is there any to implement custom logic only when user actually changes the value and not during object initialization?

Answer 1

create ViewModel Class with 3 Properties

1. Quantity{get;set}

2. Price{get;set}

3. Amount{get;}

Use INotifyPropertyChanged to Notify changes In Property.

public int Quantity
{
     get { return quantity; }
     set
     {
        quantity= value;
        NotifyPropertyChanged("Quantity");
        NotifyPropertyChanged("Amount");
     }
 }

public int Price
{
     get { return price; }
     set
     {
         price= value;
         NotifyPropertyChanged("Price");
         NotifyPropertyChanged("Amount");
     }
}

public long Amount
{
    get { return (Amount*Price); }
}

Change Any Property ie Quantity or Price, Amount will Automatically Updated with NotifyPropertyChanged

Update Property Logic can be written in Model Class

Answer 2

Try to implement this logic in controller action. Show us some code - it will be easier to find out what kind of logic you'd like to add.