Property bindings

Property bindings are very important in the MVVM pattern. The binding system in Catel will automatically map properties when the binding system is used.

Binding properties one way

To bind properties one way, use the code below.

Android

protected override void AddBindings(BindingContext bindingContext, IViewModel viewModel)
{
    var vm = (MainViewModel) viewModel;

    bindingContext.AddBinding(() => vm.FirstName, () => _firstNameEditText.Text, BindingMode.OneWay);
}

iOS

iOS not yet documented

Binding properties two way

To bind properties two way, use the code below.

Android

protected override void AddBindings(BindingContext bindingContext, IViewModel viewModel)
{
    var vm = (MainViewModel) viewModel;

    bindingContext.AddBinding(() => vm.FirstName, () => _firstNameEditText.Text).AddTargetEvent("TextChanged");
}

Note that you need to use the AddTargetEvent to allow two way binding in Android

iOS

iOS not yet documented

Binding properties with a converter

Converters are a well-known topic in MVVM. Catel supports the use of converters in the binding system. The example below will convert an integer (vm.Counter) to a string with a format to ”{0} clicks!”. The converter will automatically be instantiated using theĀ TypeFactory. Note that using converters in Catel support both TwoWay bindings and ConverterHelper.UnsetValue to prevent any changes in the binding system.

Android

protected override void AddBindings(BindingContext bindingContext, IViewModel viewModel)
{
    var vm = (MainViewModel) viewModel;

    bindingContext.AddBindingWithConverter<ClicksConverter>(() => vm.Counter, () => _testButton.Text, BindingMode.OneWay);
}

iOS

iOS not yet documented


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