Forum Xamarin Xamarin.Forms

Xamarin update viewmodel with command / improve my approach

currently I don't know how to solve my problem. I am writing an app with xamarin.forms.

I have a view which contains the userprofile of the user. For example there is a entry with the username. The field is binded in the twoway mode to the viewmodel:

<Entry x:Name="givennameSurname"  Text="{Binding FullName, Mode=TwoWay}" />,

The whole userprofile contains some fields which are validated with a behavior:

<behaviors:TelNumBehavior x:Name="NumValidatorUser" IsValid="{Binding Source={x:Reference root}, Path=BindingContext.UserTelNumBehavior, Mode=TwoWay }"></behaviors:TelNumBehavior>

The isValid property is also binded to the viewmodel.

What I want to achieve? I want, that if one of the behaviors validate the input to false, that the userprofile can not be updated.

So I wanted to create a command on a button. The button has an canExecute method: this method checks the booleans in the viewmodel if they all are true or false. If true, I want to force a refresh of the data of viewmodel from the view. I use that canExecute also to prevent unwanted changes, if the UI is in the state, that some input is wrong:

public string FullName
    get => profile.GivenName;
        if (CanSave())
                profile.GivenName = value;

What is the problem? I change an input with a behavior, so that the behavior says the input is wrong. Then I edit the username. Then I change the input of the wrong-behavior to true. Now the input of the username does not refresh in the viewmodel. I want to refresh it with the command, but I don't know how to force a refresh from the view to the viewmodel.

Maybe someone can help me solving the problem or tell me a better approach to do that? :-)

Best Answer


  • chris00rchris00r Member ✭✭

    I ended up in that approach, but I am still not happy with that at all. But I think it is okay.

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