How to create IsDirty inside OnPropertyChange, but at the same time turn it off when entities are loaded from a database

Question

I’m building WPF app, and I got to the point where I want to be able to check whether an entity IsDirty, so I found this solution online:

private bool isDirty;

    public virtual bool IsDirty
    {
        get { return isDirty; }
        set { isDirty = value; }
    }

    public event PropertyChangedEventHandler PropertyChanged = delegate { };

    protected void OnPropertyChanged([CallerMemberName] string propertyName = "")
    {
        OnPropertyChanged(true, propertyName);
    }

    protected void OnPropertyChanged(bool makeDirty, [CallerMemberName] string propertyName = "")
    {
        PropertyChanged(this, new PropertyChangedEventArgs(propertyName));

        if (makeDirty)
        {
            isDirty = makeDirty;
        }
    }

Then I can use it like this

    [Required(ErrorMessage = ErrorMessages.DescriptionRequired)]
    [StringLength(60, ErrorMessage = ErrorMessages.DescriptionLength60)]
    public string Description
    {
        get { return description; }
        set
        {
            if (description != value)
            {
                description = value;
                OnPropertyChanged();
            }
        }
    }

And it seems to work, anytime a property is changed the entity will get dirty because OnPropertyChanged is called. The problem I have is when I load an entity (or collection of entities) from a database, then onpropertychanged is called:

SomeEntitiesCollection = new Service().SomeEntities();

Then each entity which comes is marked as dirty, and I cannot find anyway around it, apart from going through a loop and setting IsDirty back to false. Is there anyother way of achieving it?

Regards

Answer 1

no, there isn't an easy way

you should override your method that retrieve entities from db in a way that it sets automatically Isdirty=false on entity creation. I used nhibernate interceptor and events to do something similar but it is not your case.

another way is to keep a copy of all the original values and compute the dirtiness when anyone asks for it. So instead of using a isdirty property you should create a method and save an initial state for all properties