R3Utility

A utility library for Cysharp/R3 that provides enhanced reactive programming capabilities, focusing on validation and property binding.

Features

Two-Way Binding Extensions

• Convert INotifyPropertyChanged properties to BindableReactiveProperty
• Automatic value propagation in both directions
• Support for deep property path binding (up to 3 levels)

Reactive Validation

• Combine multiple boolean observables with various logical operations
• Support for creating executable command sources based on validation states

Observable Element Property Monitoring (New)

• Observe changes in specific properties of elements within a collection.
• Customizable option, pushCurrentValueOnSubscribe to control initial value emission.
• Support for deep property path binding (up to 3 levels)

API Reference

ReactivePropertyExtensions

Method	Parameters	Return Type	Description
ToTwoWayBindableReactiveProperty<T, TProperty>	T value, Expression<Func<T, TProperty>> propertySelector	BindableReactiveProperty<TProperty>	Converts a single property to two-way bindable reactive property
ToTwoWayBindableReactiveProperty<T, TProperty1, TProperty2>	T value, Func<T, TProperty1?> propertySelector1, Func<TProperty1, TProperty2> propertySelector2	BindableReactiveProperty<TProperty2>	Converts a nested property (2 levels) to two-way bindable reactive property
ToTwoWayBindableReactiveProperty<T, TProperty1, TProperty2, TProperty3>	T value, Func<T, TProperty1?> propertySelector1, Func<TProperty1, TProperty2?> propertySelector2, Func<TProperty2, TProperty3> propertySelector3	BindableReactiveProperty<TProperty3>	Converts a deeply nested property (3 levels) to two-way bindable reactive property

ReactiveValidationHelper

Method	Parameters	Return Type	Description
CombineLatestValuesAreAllFalse	IEnumerable<Observable<bool>>	Observable<bool>	Combines multiple observables and returns true only when all source values are false
CombineLatestValuesAreAllTrue	IEnumerable<Observable<bool>>	Observable<bool>	Combines multiple observables and returns true only when all source values are true
CombineLatestValuesAreAnyFalse	IEnumerable<Observable<bool>>	Observable<bool>	Combines multiple observables and returns true when any source value is false
CombineLatestValuesAreAnyTrue	IEnumerable<Observable<bool>>	Observable<bool>	Combines multiple observables and returns true when any source value is true
CreateCanExecuteSource	IBindableReactiveProperty[]	Observable<bool>	Creates an observable that monitors HasErrors property of multiple BindableReactiveProperty instances

ObservableCollectionsExtensions

Method	Parameters	Return Type	Description
ObserveElementProperty<T, TProperty>	IObservableCollection<T> source, Func<T, TProperty> propertySelector, bool pushCurrentValueOnSubscribe = true, CancellationToken cancellationToken = default	Observable<PropertyPack<T, TProperty>>	Observes a specific property of each element in a collection and emits its values.
ObserveElementProperty<T, TProperty1, TProperty2>	IObservableCollection<T> source, Func<T, TProperty1?> propertySelector1, Func<TProperty1, TProperty2> propertySelector2, bool pushCurrentValueOnSubscribe = true, CancellationToken cancellationToken = default	Observable<PropertyPack<T, TProperty2>>	Observes a nested property (2 levels) in a collection and emits its values.
ObserveElementProperty<T, TProperty1, TProperty2, TProperty3>	IObservableCollection<T> source, Func<T, TProperty1?> propertySelector1, Func<TProperty1, TProperty2> propertySelector2, Func<TProperty2, TProperty3> propertySelector3, bool pushCurrentValueOnSubscribe = true, CancellationToken cancellationToken = default	Observable<PropertyPack<T, TProperty3>>	Observes a deeply nested property (3 levels) in a collection and emits its values.

Usage Examples

Two-Way Binding

// Create a BindableReactiveProperty<T> that is two-way bound
BindableReactiveProperty<string> name = item.ToTwoWayBindableReactiveProperty(x => x.Name);

// This will also update the Name property of the item object
name.Value = "X"; //item.Name = "X"

// This will also update the Value property of the BindableReactiveProperty
item.Name = "Y"; //name.Value = "Y"


// Deep property path binding
BindableReactiveProperty<string> nestedProperty = viewModel.ToTwoWayBindableReactiveProperty(
    x => x.User,
    x => x.Profile,
    x => x.DisplayName
);

Validation Helpers

// Combine multiple validation states
Observable<bool> isValid = ReactiveValidationHelper.CombineLatestValuesAreAllTrue(
      emailValidation,
      passwordValidation,
      termsAccepted
);

// Create executable command source
Observable<bool> canExecute = ReactiveValidationHelper.CreateCanExecuteSource(
      emailProperty,
      passwordProperty
);
command = canExecute.ToReactiveCommand();

Observing Properties in a Collection

using ObservableCollections;
using R3;
using R3Utility;

ObservableList<Item> collection = [];
Item item1 = new() { Name = "foo" };

collection.Add(item1);
var disposable = collection.ObserveElementProperty(x => x.Name, pushCurrentValueOnSubscribe: false)
                           .Subscribe(property => Console.WriteLine($"Instance:{property.Instance}, propertyName:{property.PropertyName}, Value:{property.Value}"));
        
//Changes are output. `Instance:WpfApp1.Item, propertyName:Name, Value:bar`
item1.Name = "bar";

disposable.Dispose();

Installation

dotnet add package R3Utility

License

R3Utility is distributed under a free and open-source license. Feel free to use it in your projects!

Contributions

We welcome contributions to the R3Utility project! If you have any suggestions, bug reports, or feature requests, please feel free to open an issue or submit a pull request. We're excited to make R3Utility better together.