CODEWITHSUNDEEP
c#xamarinxamarin.forms
Iago Antunes
Iago Antunes

Reputation: 1

Parameters commands to ViewModel

I need to pass a SearchBar Text as a parameter to the ViewModel but I don't know how to do that. The only way I could was getting the text in the Code-Behind and sending it to ViewModel by parameter

Shop.xml

SearchCommand="{Binding PesquisarButton}" SearchCommandParameter="{Binding .}" TextChanged="TextoMudou"

<SearchBar x:Name="searchBar" Grid.Column="0" Grid.Row="1" Margin="-5,10,0,10" BackgroundColor="Transparent" SearchCommand="{Binding PesquisarButton}" SearchCommandParameter="{Binding .}" TextChanged="TextoMudou" />

Shop.cs

here I take the text and send it as a parameter to the ViewModel , but I believe it's a bad way

        private void TextoMudou(object sender, EventArgs args)
        {
            palavra = ((SearchBar)sender).Text;
            BindingContext = new ViewModel.ShopViewModel(palavra);
        }

ShopViewModel.cs

I created a 'Text' variable where to store the word that came by parameter and use it in the command

public string Texto { get; set; }

Constructor

public ShopViewModel(string palavra="")
{
   this.Texto = palavra;
}

Command

Here I use the text variable I created, but I wanted this command to receive the parameter

public ICommand btnBuscar => new Command(() =>
        {
            var ListaFiltrada2 = ListaRoupas.Where((item)=> item.Nome.Contains(Texto)).ToList();
            Preencher(ListaFiltrada2);
        });

what I want is for the SearchBar Text to come straight to the Command in the viewmodel, is there any way? Github: https://github.com/IagoAntunes/FashionShop/tree/master/LojaRoupas/LojaRoupas

Upvotes: 0

Views: 597

Answers (3)

Alexandar May - MSFT
Alexandar May - MSFT

Reputation: 10078

You need create a SearchCommand in your ViewModel as below:

public ICommand PerformSearch { get; set; }

In the view model constructor:

        public SearchPageViewModel()
        {
            PerformSearch = new Command<string>
             ((string query) =>
             {
                 //use the query parameter for searching
             });
        }

Below is the XMAL. As you can see, I used a little trick that lets you pass the Text property through as a CommandParameter, saving you the effort of binding a Text property and using that.

     <SearchBar x:Name="searchBar"
               HorizontalOptions="Fill"
               VerticalOptions="CenterAndExpand"
             
               SearchCommand="{Binding PerformSearch}" 
               SearchCommandParameter="{Binding Text, Source={x:Reference searchBar}}"/>

Upvotes: 1

techie
techie

Reputation: 463

You can pass your command to receive a function that handle the process. For example:

Your XAML:

<Button Text="OK"
        BackgroundColor="#228B22"
        BorderRadius="10"
        Command="{Binding SaveCommand}"/>

Then in your ViewModel (using async as a best practice):

private Command _SaveCommand;
public Command SaveCommand => _SaveCommand ??= new Command(async () => await SaveCommandExecAsync(string texto));


private async Task SaveCommandExecAsync(string texto)
{
   string text = texto;
   var ListaFiltrada2 = ListaRoupas.Where((item)=> item.Nome.Contains(text)).ToList();
   Preencher(ListaFiltrada2);
}

Upvotes: 0

Amjad S.
Amjad S.

Reputation: 1241

You can send any object in the command like this:

public Command<object> btnBuscar { get; set; }
 
public ViewModel() // Constructor
{          
 btnBuscar = new Command<object>(btnBuscarFunction);
}

private void btnBuscarFunction (object obj){

//Parse obj to any Type you want 
string Texto = (string)obj;
 var ListaFiltrada2 = ListaRoupas.Where((item)=> item.Nome.Contains(Texto)).ToList();
            Preencher(ListaFiltrada2);
}

Upvotes: 0

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