我的MAUI.net应用程序需要处理几个数据库，一个是不同的球队，另一个是参与者。我想使用选择器，以便在创建/编辑参与者的详细信息时选择其小队，但当我打开参与者查看其详细信息时，我最终得到一个空的选择器。在调试时，当我保存/加载一个参与者时，我可以看到SelectedSquad被正确设置，但是尽管有SelectedItem绑定，它也没有出现在选择器中。
我的参与者视图模型（包含有关参与者的标准信息以及从Squad数据库中提取的信息）：

using MatchTracker.Pages;
using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using System.Collections.ObjectModel;
using System.Diagnostics;
using System.Web;

namespace MatchTracker.Models.ViewModels
{
    public partial class ParticipantDetailsVM : BaseViewModel, IQueryAttributable
    {

        [ObservableProperty]
        Participant currentParticipant;

        [ObservableProperty]
        Squad selectedSquad;

        public ObservableCollection<Squad> SquadsList { get; }

        [ObservableProperty]
        public string saveButtonText;

        public ParticipantDetailsVM()
        {
            Title = "Participant Details";
            SquadsList = new ObservableCollection<Squad>();
        }

        public async void ApplyQueryAttributes(IDictionary<string, object> query)
        {
            if (int.TryParse(HttpUtility.UrlDecode(query["id"].ToString()), out int Id))
                if (Id == 0)
                {
                    SaveButtonText = "Add Participant";
                    CurrentParticipant = new Participant { Id = 0 };
                }
                else
                {
                    SaveButtonText = "Update participant";
                    CurrentParticipant = await App._ParticipantsDb.GetAsync(Id);
                }
        }

        async Task LoadSquads()
        {
            try
            {
                SquadsList.Clear();

                var all = await App._SquadsDb.GetAllAsync();
                foreach (var item in all)
                {
                    SquadsList.Add(item);
                }
            
                SelectedSquad = await App._SquadsDb.GetAsync(CurrentParticipant.SquadId);
            }
            catch (Exception ex)
            {
                Debug.WriteLine(ex);
            }
            finally
            {
                RefreshNeeded = false;
            }
        }

        [RelayCommand]
        async Task SaveParticipant()
        {
            try
            {
                CurrentParticipant.SquadId = SelectedSquad.Id;
                await App._ParticipantsDb.AddAsync(CurrentParticipant);
                await Shell.Current.GoToAsync(nameof(ParticipantsListView));

            } catch (Exception ex)
            {
                Debug.WriteLine(ex);
            }
        }

        public async void OnAppearing()
        {
            await LoadSquads();
        }
    }
}

我的参与者视图的XAML文件：

<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="MatchTracker.Pages.ParticipantDetailsView"
             xmlns:vm="clr-namespace:MatchTracker.Models.ViewModels"
             x:DataType="vm:ParticipantDetailsVM"
             Title="{Binding Title}">
    <VerticalStackLayout>
        <TableView Intent="Data">
            <TableRoot>
                <TableSection Title="Basic Information">
                    <EntryCell x:Name="ParticipantNameField" Label="Name" Text="{Binding CurrentParticipant.Name, Mode=TwoWay}" />
                </TableSection>
            </TableRoot>
        </TableView>
        <Picker x:Name="ParticipantSquadPicker" Title="Squad" ItemsSource="{Binding SquadsList}" SelectedItem="{Binding SelectedSquad, Mode=TwoWay}" ItemDisplayBinding="{Binding Name}"/>
        <Label x:Name="Debug" Text="{Binding CurrentParticipant.SquadId}"/>
        <Button x:Name="SaveButton" Text="{Binding SaveButtonText}" Command="{Binding SaveParticipantCommand}"/>
    </VerticalStackLayout>
</ContentPage>

链接到上一个XAML文件的.cs文件：

using MatchTracker.Models.ViewModels;

namespace MatchTracker.Pages;

public partial class ParticipantDetailsView : ContentPage
{
    public ParticipantDetailsView(ParticipantDetailsVM vm)
    {
        InitializeComponent();
        BindingContext = vm;
    }
    protected override void OnAppearing()
    {
        base.OnAppearing();
        ((ParticipantDetailsVM)BindingContext)?.OnAppearing();
    }
}