Agfdhyk

I am using to Picker in my project. I am successfully able to display the All items in the Picker without an issue but for update functionality, I am not able to display the Default Item for Picker,

I have used SelectedItem and SelectedIndex but nothing worked in my case.

Can someone explain how that SelectedItem and SelectedIndex works,

My code:

<Picker Title="Select Gender" Margin="0,0,0,-5" ItemsSource="{Binding GenderList}"  x:Name="pkrGender" ItemDisplayBinding="{Binding Name}" >

In view Model:

public class MainViewModel : BaseViewModel 

{

 // Which is bind to ItemSource of the picker

 public ObservableCollection<Gender> GenderList { get; set; }    



 public class Gender: BaseViewModel {

  private Genders _gender {

   get;

   set;

  }



  public Gender(Genders gender) {

   this._gender = gender;

  }





  public string Name {

   get {

    return _gender.name;

   }



   set {

    _gender.name = value;

    OnPropertyChanged("Name");

   }

  }



 }

 public void APICALL()

 { 

   // Getting values from API

 }



}   

And Genders Class:

public class Genders

{

   public string Name {get;set;}

   public string Code {get;set;}

}

And I am Adding the values in ViewModel like:

// From API Response Getting the list of Genders

var genderList = APICALL();

foreach (Genders gender in genderList)

{

    GendersList.Add(new Genders(gender));

}

But not able to bind the default value In my case he selected the Male while registration so the Male should be the Default value for the picker.

Fundamentally, I think you're missing the OnPropertyChanged method in the GenderList property. As a result, your Picker is bound to an empty list.

I found the following worked for me:

private List<Genders> listOfGenders = new List<Genders>();



public List<Genders> GenderList

{

    get => listOfGenders;

    set 

    {

        listOfGenders = value;

        OnPropertyChanged(nameof(GenderList));

    }

}



private void AddToGenderList(params Gender genders)

{

    if (listOfGenders == null)

    {

        listOfGenders = new List<Genders>();

    }



    foreach(Gender gender in genders)

    {

        listOfGenders.Add(gender);

    }



    GendersList = listOfGenders;

}

How do the SelectedItem and SelectedIndex work?

SelectedItem returns the selected object from the list associated to the Picker. In your case, it will return the Gender object that you selected.

SelectedIndex returns the index of the item you selected in the list.

Assigning a default value

To assign a default value, first make sure that the list is not empty. For example, the code below (expanding from the code above) should work:

(In your C#)

private int currentSelectedIndex = 0;



public int CurrentSelectedIndex

{

    get => currentSelectedIndex;

    set

    {

        currentSelectedIndex = value;

        OnPropertyChanged(nameof(CurrentSelectedIndex));

    }

}



public MainViewModel()

{

    AddToGenderList(new Gender 

    {

        new Gender

        {

            Name = "Male",

            Code = "M"

        },

        new Gender

        {

            Name = "Female",

            Code = "F"

        },

        new Gender

        {

            Name = "Other",

            Code = "O"

        }

        // Add more if necessary

    });



    // Set the default to "Male"

    CurrentSelectedIndex = 0;

}

(In your XAML)

<Picker 

    Title="Select Gender" 

    Margin="0,0,0,-5" 

    ItemsSource="{Binding GenderList}"  

    SelectedIndex="{Binding CurrentSelectedIndex}"

    x:Name="pkrGender" 

    ItemDisplayBinding="{Binding Name}" />