[英]ReactiveUI 6 instant search (MVVM)
我想对用户在文本框中的键入做出反应。
实际上,我的问题类似于在WPF / MVVM的Reactive Extensions Instant Search中发布的内容。
现在我们处于ReactiveUI的第6版,以前的代码已经过时了。 如何实现它(使用MVVM,即不使用事件)?
引人注目的示例@ http://reactiveui.net/应该有很多帮助。 您还想确保您的xaml TextBox使用UpdateSourceTrigger
<TextBox Text="{Binding SearchQuery, UpdateSourceTrigger=PropertyChanged}" Width="50" />
来自RXUI的代码复制到此处:
public class SearchViewModel : ReactiveObject, IRoutableViewHost
{
public ReactiveList<SearchResults> SearchResults { get; set; }
private string searchQuery;
public string SearchQuery {
get { return searchQuery; }
set { this.RaiseAndSetIfChanged(ref searchQuery, value); }
}
public ReactiveCommand<List<SearchResults>> Search { get; set; }
public ISearchService SearchService { get; set; }
}
和构造函数代码
// Constructor
public SearchViewModel(ISearchService searchService = null)
{
SearchService = searchService ?? Locator.Current.GetService<ISearchService>();
// Here we're describing here, in a *declarative way*, the conditions in
// which the Search command is enabled. Now our Command IsEnabled is
// perfectly efficient, because we're only updating the UI in the scenario
// when it should change.
var canSearch = this.WhenAny(x => x.SearchQuery, x => !String.IsNullOrWhiteSpace(x.Value));
// ReactiveCommand has built-in support for background operations and
// guarantees that this block will only run exactly once at a time, and
// that the CanExecute will auto-disable and that property IsExecuting will
// be set according whilst it is running.
Search = ReactiveCommand.CreateAsyncTask(canSearch, async _ => {
return await searchService.Search(this.SearchQuery);
});
// ReactiveCommands are themselves IObservables, whose value are the results
// from the async method, guaranteed to arrive on the UI thread. We're going
// to take the list of search results that the background operation loaded,
// and them into our SearchResults.
Search.Subscribe(results => {
SearchResults.Clear();
SearchResults.AddRange(results);
});
// ThrownExceptions is any exception thrown from the CreateAsyncTask piped
// to this Observable. Subscribing to this allows you to handle errors on
// the UI thread.
Search.ThrownExceptions
.Subscribe(ex => {
UserError.Throw("Potential Network Connectivity Error", ex);
});
// Whenever the Search query changes, we're going to wait for one second
// of "dead airtime", then automatically invoke the subscribe command.
this.WhenAnyValue(x => x.SearchQuery)
.Throttle(TimeSpan.FromSeconds(1), RxApp.MainThreadScheduler)
.InvokeCommand(this, x => x.Search);
}
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