CODEWITHSUNDEEP
xamlxamarinxamarin.formspicker
Lex
Lex

Reputation: 891

Xamarin picker, not setting default value

I've got a picker on the screen, that has an initial value, as well as the option to change the item in the picker.

While my selectedItem is set, I don't see that on the picker on the screen, the picker has no value set, and it's not until I select a value, that it actually displays something in the picker on the screen (At this time the SelectedItem is also updated with the new value).

My xaml:

    <Picker
       ItemsSource="{Binding FeedbackTypes}"
       SelectedItem="{Binding SelectedFeedbackType, Mode=TwoWay}"
       ItemDisplayBinding="{Binding Name}">
   </Picker>

My ViewModel properties: 

private ValueName _selectedFeedbackType;

public ValueName SelectedFeedbackType
{
  get { return _selectedFeedbackType; }

  set
  {
    _selectedFeedbackType = value;
    OnPropertyChanged(nameof(SelectedFeedbackType));
  }
}

public ObservableCollection<ValueName> FeedbackTypes
{
  get
  {
    var feedbackTypes = new ObservableCollection<ValueName>();

    foreach (FeedbackType feedback in 
             Enum.GetValues(typeof(FeedbackType)))
    {
      feedbackTypes.Add(new ValueName
      {
        Value = feedback,
        Name = feedback.ToName()
       });
     }

   return feedbackTypes;
  }
}

And in my ViewModel constructor I've got: 

SelectedFeedbackType = new ValueName { Value = feedbackType, Name = feedbackType.ToName() };

The constructor works sets the SelectedFeedbackType correctly and if I don't make any changes to the picker, that is the value I get in there on submit, however, I do not see that value in the picker by default. The picker is empty until a selection is made.

I've also tried to bind the SelectedIndex value to the SelectedFeedbackType, however that one will not show the initially selected value either in the picker.

Upvotes: 1

Views: 2927

Answers (1)

Leon Lu
Leon Lu

Reputation: 9234

You could try to set defalut value of the Xamarin Picker. You just set the selectedIndex(the first number of index is 0) of your picker like the following code.

Mypicker.SelectedIndex=1;

There is a code of demo.

GIF of demo when first running. enter image description here

You can download this demo by the link. https://developer.xamarin.com/samples/xamarin-forms/UserInterface/PickerDemo/

Then changed the code of MonkeysPage.xaml.

 <Picker x:Name="Mypicker" Title="Baboon" ItemsSource="{Binding Monkeys}" ItemDisplayBinding="{Binding Name}" SelectedItem="{Binding SelectedMonkey}" />

Add the defaule value of Pickerin MonkeysPage.xaml.cs.

    public MonkeysPage()
    {
        InitializeComponent();
        BindingContext = new MonkeysPageViewModel();
        Mypicker.SelectedIndex=1;

    }
}

Upvotes: 1

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