How to use Xamarin to call an UI Element with a bound name - xaml

Question

I'm trying to use a custom variable to name UI Elements in XAML in order to use them in my Xamarin code. How would I do that?
I know that I can use the tags
<Label x:Name="CallVariable" Text="This will appear"/>
and I can call the label from Xamarin using
Label foo = FindByName("CallVariable") as Label;
and mess with the text with the following
foo.Text == "This will appear"
which should return true.
I learned about binding, and so I tried to use this in my variables.
<Label x:Name={Binding Name}/>
Label bar = FindByName(emp.training[i] as Label);
Unfortunately, every time I run it, I'm receiving the error:
System.NullReferenceException: Object reference not set to an instance of an object.
I remembered to set the BindingContext. And in case it's important, this is all happening within a list view.
Is x:Name a bindable object? Or is there another method I should be using? Maybe a way to call an object based on its label, or something?
My current task is as follows:
I have a list of people's information. Name, Age, Gender, Email, Location, and a few other pieces of information. I'm trying to get someone to search for certain types of people, have it return a list of everyone in a ListView, and have the person be able to select as many as they want. I did this using a button that adds the person to a list (or removes them from the list if they're already on). If the user chooses to, they should be able to also click "Select All" to add everyone. I've got the individual adding down, I just need to somehow select all of them.

Answer 1

You can't access the label with a listView by x:Name in code behind. Instead of access the label in the listView, you can bind the property of label in code behind. For example:
<ListView x:Name="testListView">
<ListView.ItemTemplate>
<DataTemplate>
<ViewCell>
<StackLayout>
<Label Text="{Binding Name}" />
<Label Text="{Binding Desc}" />
</StackLayout>
</ViewCell>
</DataTemplate>
</ListView.ItemTemplate>
</ListView>
And in code behind, it should be:
public partial class MainPage : ContentPage
{
ObservableCollection<testViewModel> myModels = new ObservableCollection<testViewModel>();
testViewModel model;
public MainPage()
{
InitializeComponent();
testListView.ItemsSource = myModels;
myModels.Add(new testViewModel { Name = "age" });
myModels.Add(new testViewModel { Name = "gender" });
myModels.Add(new testViewModel { Name = "name" });
}
}
class testViewModel
{
public string Name { get; set; }
public string Desc { get; set; }
}
Next time you want to update the text of label:
public void test() {
//Get the model you want to change
model.Desc = "This will appear";
}
I've got the individual adding down, I just need to somehow select
all of them.
I don't know how you implement the individual adding down, share the code and maybe I can give you some suggestions.