>Net Maui - Passing object between pages

Question

I'm having trouble getting my DetailsPage to show the Observation obs object passed from my ResultsPage. I have a TapGestureRecognizer_Tapped method in the code behind the ResultsPage

private async void TapGestureRecognizer_Tapped(object sender, TappedEventArgs e)
{
    if (((VisualElement)sender).BindingContext is not Observation obs)
        return;
    var navigationParameter = new ShellNavigationQueryParameters
    {
        {"Observation", obs }
    };
    await Shell.Current.GoToAsync(nameof(DetailsPage), navigationParameter);
}

and on my DetailsPage ViewModel the following initialization code

using CommunityToolkit.Mvvm.ComponentModel;
using CommunityToolkit.Mvvm.Input;
using SunObs.Models;
using SunObs.Services;
namespace SunObs.ViewModel
{
    [QueryProperty(nameof(Observation), "Observation")]
    public partial class DetailsViewModel : BaseViewModel
    {
        [ObservableProperty]
        Observation obs;
        [ObservableProperty]
        [NotifyCanExecuteChangedFor(nameof(UpdateObservationAsyncCommand))]
        private bool calcDone;
        public IAsyncRelayCommand ComputeObsAsyncCommand { get; }
        public IAsyncRelayCommand UpdateObservationAsyncCommand { get; }
        readonly ObservationService _observationService;
        public DetailsViewModel(ObservationService observationService)
        {
            Title = "Edit Observation";
            _observationService = observationService;
            CalcDone = false;
            ComputeObsAsyncCommand = new AsyncRelayCommand(ComputeObsAsync);
            UpdateObservationAsyncCommand = new AsyncRelayCommand(UpdateObservationAsync);
        }

The details ContentPage has the following

<?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="SunObs.Views.DetailsPage"
            xmlns:converters="clr-namespace:SunObs.Converters"
            xmlns:toolkit="http://schemas.microsoft.com/dotnet/2022/maui/toolkit"
            xmlns:local="clr-namespace:SunObs.Models"
            xmlns:model="clr-namespace:SunObs.Models"
            xmlns:viewmodel="clr-namespace:SunObs.ViewModel"
            x:DataType="viewmodel:DetailsViewModel"
            Title="{Binding Obs.Id, StringFormat='Edit Observation : {0}'}">
    <ContentPage.Resources>
        <converters:AngleConverter x:Key="AngConv"/>
    </ContentPage.Resources>
    <Shell.BackButtonBehavior>
        <BackButtonBehavior IsEnabled="False"/>
    </Shell.BackButtonBehavior>
    <VerticalStackLayout BackgroundColor="Transparent" Spacing="10" Margin="10,10,10,0">
        <Grid RowDefinitions="Auto, Auto, Auto, Auto, Auto, Auto, Auto, Auto, Auto, Auto, Auto, Auto, Auto, Auto, Auto, Auto, Auto, Auto"
          ColumnDefinitions="Auto,*" RowSpacing="5" ColumnSpacing="5" Margin="8">
            
            <Border Grid.Row="2" Grid.Column="0" Style="{StaticResource borderinput}">
                <Label Style="{StaticResource lbl}" Text="Observation Date"/>
            </Border>
            <DatePicker Grid.Row="2" Grid.Column="1"
                        x:Name="DPicker" Date="{Binding Obs.ObsDate}"
                        VerticalOptions="Center" 
                        DatePicker.Format="dd-MMM-yyyy"/>
            
            <Border Grid.Row="3" Grid.Column="0" Style="{StaticResource borderinput}">
                <Label Style="{StaticResource lbl}" Text="Watch Time"/>
            </Border>
            <Entry Placeholder="00:00:00" PlaceholderColor="Blue"
                    x:Name="WT" Text="{Binding Obs.WT}"
                    VerticalOptions="Center"
                    Grid.Row="3" Grid.Column="1">
                <Entry.Behaviors>
                    <toolkit:SelectAllTextBehavior />
                </Entry.Behaviors>
            </Entry>

to bind the Observation object obs along with all the other properties needed.

However, when the page displays, all the properties are set to zero. I've watched many videos and read the documentation. Can you please show me how to pass the object correctly.

TIA

Answer 1

Solved it myself.