MVVM Validation With Entity Framework

Question

i'm currently working on a project using MVVM and Entity Framework Code First Model. So i implemented IDataErrorInfo and INotifyPropertyChanged in my model classes. Now, in my viewmodel i implemented a SaveCommand and a CanSave boolean method, my question is how can i raise canexecutechanged for the whole entity and not individual properties? since my properties already implemented InotifyPropertyChanged in model.

This is my Model Class

 public class Guest:ValidatableBindableClass
{
    //my properties here
    //implement InotifyPropertyChanged and IDataErrorInfo
}

This is my ViewModelClass:

 public class AddEditGuestViewModel:BindableClass
{
    private Hospede guest;
    public RelayCommand SaveCommand  { get; set; }
    private readonly Hmsdb.HMS context = new Hmsdb.HMS();

    public Hospede Guest
    {
        get { return guest; }
        set { SetProperty(ref guest, value, propertyName: "Guest"); }
    }

    private void OnSave()
    {

        context.Hospedes.Add(Guest);
        context.SaveChanges();
    }

    private bool CanSave()
    {
        return context.Entry(Guest)
            .GetValidationResult().IsValid;
    }
}

Don't post images of code. Copy the relevant code into the question and format accordingly. Just posting images reduces the searchability of the question. — Lithium, Apr 06 '17 at 10:18

score 0 · Answer 1 · answered Apr 06 '17 at 10:24

0

You can raise the PropertyChanged event for all properties by passing null or string.Empty to the constructor of the PropertyChangedEventArgs:

PropertyChanged(this, new PropertyChangedEventArgs(null));

You will need to call the RaiseCanExecuteChanged() method of each RelayCommand though.

answered Apr 06 '17 at 10:24

mm8

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Depending on the command implementation, a call to `CommandManager.InvalidateRequerySuggested()` might be enough.. – grek40 Apr 06 '17 at 10:26
It is pretty ineffective though: http://stackoverflow.com/questions/1751966/commandmanager-invalidaterequerysuggested-isnt-fast-enough-what-can-i-do. And the entity seems to have only one command anyway. – mm8 Apr 06 '17 at 10:28
My model class already implements propertychanged event for each property, the question is how can i rise canexecute changed on viewmodel class sinse i´m binding to guest entity and not Gues.SomeProperty? Thanks for replay... – Gonguela Apr 06 '17 at 10:41
Raise CanExecuteChanged from where? – mm8 Apr 06 '17 at 10:42
@mm8 from ViewModel – Gonguela Apr 06 '17 at 10:45
@mm8 Guest is the Entity Model Implementing INotifyPropertyChanged and IDataErrorInfo not the ViewmModel – Gonguela Apr 06 '17 at 11:01
What are you talking about? Again: from where (which class) are trying to raise the event? – mm8 Apr 06 '17 at 11:03
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/140064/discussion-between-gonguela-and-mm8). – Gonguela Apr 06 '17 at 11:17

MVVM Validation With Entity Framework

1 Answers1