ReactiveCommandBase class¶

Attributes: [DebuggerDisplay("{CanExecute}, {IsExecuting}")]

Summary¶

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A base class for generic reactive commands.

classDiagram
class ReactiveCommandBase~T1,T2~
class IReactiveCommand~TParam, TResult~ {
    <>
}
IReactiveCommand~TParam, TResult~ <|.. ReactiveCommandBase~T1,T2~
class IObservable~TResult~ {
    <>
}
IObservable~TResult~ <|.. ReactiveCommandBase~T1,T2~
class IReactiveCommand {
    <>
}
IReactiveCommand <|.. ReactiveCommandBase~T1,T2~
class IDisposable {
    <>
}
IDisposable <|.. ReactiveCommandBase~T1,T2~
class IHandleObservableErrors {
    <>
}
IHandleObservableErrors <|.. ReactiveCommandBase~T1,T2~
class ICommand {
    <>
}
ICommand <|.. ReactiveCommandBase~T1,T2~

Implements: IReactiveCommand, IObservable, IReactiveCommand, IDisposable, IHandleObservableErrors, ICommand

Remarks¶

This class extends ReactiveCommand and adds generic type parameters for the parameter values passed into command execution, and the return values of command execution.

Because the result type is known by this class, it can implement IObservable. However, the implementation is defined as abstract, so subclasses must provide it.

Reactive commands encapsulate the behavior of running some execution logic and then surfacing the results on the UI thread. Importantly, no scheduling is performed against input observables (the canExecute and execution pipelines).

To create an instance of ReactiveCommand, call one of the static creation methods defined by this class. ReactiveCommand.Create can be used when your execution logic is synchronous. ReactiveCommand.CreateFromObservable and ReactiveCommand.CreateFromTask (and overloads) can be used for asynchronous execution logic. Optionally, you can provide an observable that governs the availability of the command for execution, as well as a scheduler to which events will be delivered.

The CanExecute property provides an observable that can be used to determine whether the command is eligible for execution. The value of this observable is determined by both the canExecute observable provided during command creation, and the current execution status of the command. A command that is already executing will yield false from its CanExecute observable regardless of the canExecute observable provided during command creation.

The IsExecuting property provides an observable whose value indicates whether the command is currently executing. This can be a useful means of triggering UI, such as displaying an activity indicator whilst a command is executing.

As discussed above, you are under no obligation to somehow incorporate this into your canExecute observable because that is taken care of for you. That is, if the value of IsExecuting is true, the value of CanExecute will be false. However, if the value of CanExecute is false, that does not imply the value of IsExecuting is true.

Any errors in your command's execution logic (including any canExecute observable you choose to provide) will be surfaced via the ThrownExceptions observable. This gives you the opportunity to handle the error before it triggers a default handler that tears down the application. For example, you might use this as a means of alerting the user that something has gone wrong executing the command.

For the sake of convenience, all ReactiveCommand instances are also implementations of ICommand. This allows you to easily integrate instances of ReactiveCommand into platforms that understands ICommand natively (such as WPF and UWP).

Constructors¶

Properties¶

Methods¶