inotifypropertychanged

问题 I have a WPF form with a combobox and a textbox (both are databound to an Object's property). Changing the combobox or textbox input updates the Object's property and the databinding kicks in and updates the UI. The problem is, I implemented a way to cancel the change, which works, but screws up the UI updating. If I make the change from the combobox and cancel it, the combobox does not revert the selectedvalue back to what it should be (bound by the object's value). If I make the change from

问题 I have a WPF form with a combobox and a textbox (both are databound to an Object's property). Changing the combobox or textbox input updates the Object's property and the databinding kicks in and updates the UI. The problem is, I implemented a way to cancel the change, which works, but screws up the UI updating. If I make the change from the combobox and cancel it, the combobox does not revert the selectedvalue back to what it should be (bound by the object's value). If I make the change from

问题 I currently have a setter method which looks like this: private string _a; public virtual string A { get { return _a; } set { if (_a!= value) { if (this.OnPropertyChanging("A", _a, value)) { var previousValue = _a; _a = value; this.OnPropertyChanged("A", previousValue, value); } } } } I have implemented this with help from Dr Wily's Apprentice (http://stackoverflow.com/a/8578507/981225), with a custom Changing handler that keeps track of the old and current value, as well as the ability to

问题 I have seen the following pattern used for implementing INotifyPropertyChanged private void NotifyPropertyChanged(string propertyName) { PropertyChangedEventHandler handler = PropertyChanged; if (handler != null) { handler(this, new PropertyChangedEventArgs(propertyName)); } } public event PropertyChangedEventHandler PropertyChanged; Can someone explain to me the necessity of the var handler = PropertyChanged assignment prior to checking it for null versus directly checking PropertyChanged ==

问题 I have seen the following pattern used for implementing INotifyPropertyChanged private void NotifyPropertyChanged(string propertyName) { PropertyChangedEventHandler handler = PropertyChanged; if (handler != null) { handler(this, new PropertyChangedEventArgs(propertyName)); } } public event PropertyChangedEventHandler PropertyChanged; Can someone explain to me the necessity of the var handler = PropertyChanged assignment prior to checking it for null versus directly checking PropertyChanged ==

问题 I have some nested view models that implement INotifyPropertyChanged . I'd like to bind an event listener to a nested property path (e.g. "Parent.Child.Name" ), much like FrameworkElement dependency properties can be bound to arbitrary nested properties. However, I just want something like a PropertyChanged event listener -- I don't actually have any UI element I'd like to bind. Is there any way to use the existing framework to set up such an event source? Ideally, I shouldn't need to modify

问题 I have been binding in WPF application directly to the model classes (and skipping creating individual viewmodel classes). Now, after switching to EF6 and DBContext, I face an issue with the generated EF POCO classes since it looks its either kind of tricky or not even recommended trying to make INotifyPropertyChanged interface implemented directly to those classes. Currently: I don't want to go back to ObjectContext. I don't want to change T4 too much either. The suggestions on the web for

问题 I'm new to WP8 & MVVM. I created wp8 app which requests various bits of data once a user has logged in. I just can't get my pivots header to get created dynamically and I don't know if it is because I'm doing something in the binding, the INotifyPropertyChanged, both or something else!! Here is what I have done so far: I've got a global MainViewModel defined in App.cs which will stored all the data returned at login time. Once the login is successful and the data has been loaded into the

问题 I want to add more functionality to a project I have that makes use a number of classes packaged in the NET Framework. These same classes provide a number of properties which can be quite useful adapting the functionality of my project, however one thing that these classes lack is Events. If each property had a appropriate event that would fire whenever the value of such property changed, I could then assign a event handler that would act based on those properties value. I made a sample case

问题 I have a Winform application which uses colour to highlight certain things. I would like to allow the users to change 'their' colours. As an exercise, I thought I would create an instance of a class, with properties for the colours, and assign it to a property grid (to get a nice editor) . This seems to work fine, but I then thought I would like to let the users reset the colours (after they had fiddled and set them to 20 shades of beige) . So, I added a "reset" button to my form, which set