MAUI Reading Enum from QueryProperty

Question

I have an enum:

 public enum MediaTypes
 {
     Book = 0,
     Video = 1,
     Magazine = 2,
     Picture = 3
     All = 99
 }

...which I would like to pass to a page and pull off its value as a QueryProperty in the page :

[QueryProperty("MediaType", "MediaType")]
public int MediaType { get; set; }

This works if the type is set to "int", but throws a conversion error if the type is set to what I really want it to be: a MediaTypes.

public MediaTypes MediaType { get; set; }

What's the correct way to pass/parse a QueryProperty which is an enum?

Answer 1

I suppose that "the correct way" is a matter of opinion, but one way for sure to make this work is to have the [QueryProperty] invoke a string-to-MediaTypes converter. You could have it work on either int values or named values if you like as shown.

---

Suppose you want a query like this:

private async void OnNavTestClicked(object sender, EventArgs e)
{
    await Shell.Current.GoToAsync($"///details?mediatype=book");
}

...or like this:

private async void OnNavTestClickedInt(object sender, EventArgs e)
{
    await Shell.Current.GoToAsync($"///details?mediatype=99");
}

Your "some page" class could handle the query like so:

public enum MediaTypes
{
    Book = 0,
    Video = 1,
    Magazine = 2,
    Picture = 3,
    All = 99
}
[QueryProperty(nameof(MediaTypeQuery), "mediatype")]
public partial class DetailsPage : ContentPage
{
    public DetailsPage() => InitializeComponent();

    protected override void OnNavigatedTo(NavigatedToEventArgs args)
    {
        base.OnNavigatedTo(args);
        Dispatcher.Dispatch(async ()=> 
            await DisplayAlert("Query Parameter", $"Received ID: {MediaType}", "OK"));
    }

    public string MediaTypeQuery
    {
        // Convert int or named value
        set =>
            MediaType = 
            int.TryParse(value, out int n) 
            ? (MediaTypes)n
            : Enum.TryParse(value, ignoreCase: true, out MediaTypes mediaType)
                ? mediaType
                : (MediaTypes)(-1); // Default value of your choosing
    }

    public MediaTypes MediaType { get; set; }
}