What is this library?

ReactiveUI is a powerful MVVM framework based on Rx. Dynamic Data is a portable class library based on Rx and provides an observable list and an observable cache. These collections come with a very rich set of collection specific observable operators.

This library plugs dynamic data observables into reactive ui

• ReactiveUI on GitHub
• Dynamic Data on GitHub

Create a dynamic data source

Create an observable list.

var list = new SourceList<T>();
//create an observable changeset
var observableChanges = list.Connect();

or create an observable cache.

var cache = new SourceCache<TObject,TKey>(t=>t.Key);
//create an observable changeset
var observableChanges = cache.Connect();

and that is that. You have a thread safe data source which is converted into an observable by calling .Connect(). The connect method has dozens of collection specified composable and fluent operators.

Create a dynamic data source from ReactiveList

Another way to create a dynamic data source is directly from a reactive list.

var list = new ReactiveList<T>();

From this list create a cache source or a list source as follows

var observableChanges= list.ToObservableChangSet();
//or
var observableChanges= list.ToObservableChangSet(t=>t.Key);

Integration of dynamic data and reactive ui is as easy as that.

What are the benefits of the integration between Dynamic Data and ReactiveUI

The cache part of dynamic data has about 60 operators and the list side has about 35 operators and counting. There operators are fluent and can be easily combined to form very powerful operations with very simple code. This first example illustrates binding a complex observable to a reactive list.

var myoperation = observableChanges
			.Filter(trade=>trade.Status == TradeStatus.Live) 
			.Transform(trade => new TradeProxy(trade))
			.Sort(SortExpressionComparer<TradeProxy>.Descending(t => t.Timestamp))
			.ObserveOn(RxApp.MainThreadScheduler)
			.Bind(myReactiveList) //an instance of a reactive list
			.DisposeMany()
			.Subscribe()

As changes in observableChanges are received the results are filtered by live trades, transformed into a proxy, put into a sort order and the reactive list will exactly reflect all this. When a tradeproxy is removed from the observable it is disposed and when myoperation is disposed, all trade proxys are disposed.

And of course the main point of this example is the result on any chain of operators can be reflected on the reactive list using the .Bind() method.

That was easy, declarative and powerful.

###So what else can it do

In all the examples, for readabilty I have ommited the datasource.Connect() method. All the operators are fluent and composable.

Group

Grouping is easily achieved as follows.

var myoperation = somedynamicdatasource
	         .GroupOn(person=>person.Status) 
			 .Subscribe(changeSet=>//do something with the groups)

Transformation

Dynamic data has several transformative operators

//Map to a proxy object
var myoperation = somedynamicdatasource.Transform(person=>new PersonProxy(person)) 

//transform many to flatten a child enumerable
var myoperation = somedynamicdatasource.TransformMany(person=>person.Children) 

//Create a fully formed reactibe tree
var myoperation = somedynamicdatasource.TransformToTree(person=>person.BossId) 

Aggregation

if we have a a list of people we can aggregate as follows

var people= new SourceList<Person>();
var observable = people.Connect();

var count= observable.Count();
var max= observable.Max(p=>p.Age);
var min= observable.Min(p=>p.Age);
var stdDev= observable.StdDev(p=>p.Age);

Join operators

There are And, Or and Except logical operators

var peopleA= new SourceCache<Person,string>(p=>p.Name);
var peopleB= new SourceCache<Person,string>(p=>p.Name);
var observableA = peopleA.Connect();
var observableB = peopleB.Connect();

var inBoth = observableA.And(observableB);
var inEither= observableA.Or(observableB);
var inAandNotinB = observableA.Except(observableB);

Virtualisation

There are Virtualise, Page and Top operators

//virtualise
var controller =  new VirtualisingController(new VirtualRequest(0,25));
var myoperation = somedynamicdatasource.Virtualise(controller)

//Top (overload of virtualise)
var myoperation = somedynamicdatasource.Top(10)

//page
var controller =  new PageController(new PageRequest(1,25));
var myoperation = somedynamicdatasource.Page(controller)

The parameters of the controllers above can be changes any time to force a re-evaluation.

Plus much much more...

Some links to get going

• Contact me any time on
• Master build
• Sample wpf project https://github.com/RolandPheasant/Dynamic.Trader
• Blog at http://dynamic-data.org/
• Get it from https://www.nuget.org/packages/DynamicData.ReactiveUI