How can I get shell.searchandler to push its own text? - xamarin

Question

I am trying to push the text from my Shell.SearchHandler to a command.
I have built this with SearchBar , but i need this to work in the Shell.SearchHandler
<Shell.SearchHandler >
<SearchHandler x:Name="searchBar"
Placeholder="Search..."
Command="{Binding PerformSearch}"
CommandParameter="{Binding Text, Source={x:Reference searchBar}}" TextColor="Black" BackgroundColor="LightGray" />
</Shell.SearchHandler>
And in my View model
public ICommand PerformSearch => new Command<string>((string query) =>
{
//do work
});
The command does execute but the query param is always null.
How can I get the text that was entered into the searchandler to be posted to the binding command?

Answer 1

CommandParameter="{Binding Text, Source={x:Reference searchBar}}"
After having a look at SearchHandler reference document as follow :
Query, of type string, the user entered text in the search box.
The reason is that SearchHandler not contains Text property .You should replace it with Query , then it can work .
<Shell.SearchHandler >
<SearchHandler x:Name="searchBar"
Placeholder="Search..."
Command="{Binding PerformSearch}"
CommandParameter="{Binding Query, Source={x:Reference searchBar}}"
TextColor="Black"
BackgroundColor="LightGray" />
</Shell.SearchHandler>
Note : Also can Custom a SearchHandler to monitor Query changed if needed .
Creare a MySearchHandler :
public class MySearchHandler : SearchHandler
{
protected override void OnQueryChanged(string oldValue, string newValue)
{
base.OnQueryChanged(oldValue, newValue);
if (string.IsNullOrWhiteSpace(newValue))
{
ItemsSource = null;
}
else
{
Console.WriteLine("search string " + newValue);
// here you can add code to deal with the viewmodel
//ItemsSource = MonkeyData.Monkeys
.Where(monkey => monkey.Name.ToLower().Contains(newValue.ToLower()))
.ToList<Animal>();
}
}
}
In Xaml :
<ContentPage ...
xmlns:controls="clr-namespace:Xaminals.Controls">
<Shell.SearchHandler>
<controls:MonkeySearchHandler Placeholder="Enter search term"
ShowsResults="true"
DisplayMemberName="Name" />
</Shell.SearchHandler>
...
</ContentPage>
Here is the official sample for reference , this need some time to research it.