Prism: Updating a property in ViewModel through DelegateCommand doesn't update the UI/View

[deb1bhu]

I have a code where i want to update the UI when some progress is going on in ViewModel. I set the property value to "Please wait" through some DelegateCommand. Although the value gets updated for the property but view doesn't get updated. If I change the property value through some method in ViewModel it updates the UI.

is this a known issue or bug in Prism 6?

Platform:

• Prism version: 6.
• Visual studio- 2015

code snippet
XAML: TextBlock Text="{Binding UpdateValue, Mode=TwoWay}"

in ViewModel

private string _updateValue;
public string UpdateValue
{
get
{
return this._updateValue;
}
set
{
this._updateValue = value;
this.OnPropertyChanged("UpdateValue");
}
}

Constructor:
ViewModel()
{
ConnectCommand = new DelegateCommand(ExecuteConnectionWindow);
...
}

private void ExecuteConnectionWindow(string obj)
{
_updateValue = "Please wait...";
...
}

But it doesn't change the UI property.

[dvorn]

It should be

this.UpdateValue = "Please wait...";

[deb1bhu]

I got the issue. I don't know if its a bug in prism 6 or it's the design of Prism.
However let me point out the core issue.

I thought in Prism 6.0 there is no difference between OnPropertyChanged() method and Setproperty()method except using SetProperty<T> You can reduce the set method to just one line also ref parameter allows you to update its value.

But there is a difference between OnPropertyChanged()method and Setproperty() method.
However there should not be as BindableBaseis an abstract class implements INotifyPropertyChanged().

public abstract class BindableBase : INotifyPropertyChanged
{...}

If I have a property "UpdateValue" in MainViewModel with SetProperty() method.
And I want to update the value through a "DelegateCommand". the value gets updated but it doesn't update the UI.

But for the same property value if I set "OnPropertyChanged()" then the value gets updated in the UI through "DelegateCommand".

Can anyone explain this behaviour.

[dvorn]

There is no difference in behavior. Provide the code that does not work for you.

[deb1bhu]

I have attached the code here. Sorry for the late reply as I have to create a new project and then share.
PrismDummyApp.zip

Thanks

[dvorn]

@deb1bhu You should not set the value of the underlying field before calling SetProperty. SetProperty sees that the value did not changed and does nothing:

_updateValue1 = value; // <<<< remove that
SetProperty(ref _updateValue1, value);

[deb1bhu]

Ohhh
Thanks for the help. It really works.

[lock[bot]]

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