[Bug] Multibinding converter (possibly multibinding in general) is not working in XAML, works in C#

[ziomek64]

Description

So today I've made myself IMultiValueConverter but it wasn't working for me. All the objects in value array are null. I've tried looking for any typos in paths but couldn't find anything. Then I swapped it with c# and it just works. I tried cleaning project, rebuilding. See the project below. The xaml code is there, and I've also commented c# so you can try them both one after another. I've tried looking for any mistake in xaml with someone experienced but we didn't find anything

I don't know if it's a bug with Multibinding converter or multibinding in general. I don't know if it's a bug at all, but I couldn't find typos.

Steps to Reproduce

Make a page, some IMultiValueConverter, bind objects

Expected Behavior

Works in both XAML and C# with values visible in debugger

Actual Behavior

Works in C# only, xaml objects in array are null

Basic Information

• Version with issue: Newest
• Last known good version: Don't know, i've tried pre 5.0 versions
• Platform Target Frameworks: I have only Android, can't check anything else. Target android 11
• Android Support Library / AndroidX Version: Newest
• NuGet Packages: Just Xamarin.Forms fresh project
• Affected Devices:

Reproduction Link

https://github.com/ziomek64/MultiBinding-not-working-test-project

Workaround

Use c#

[jfversluis]

Hi there! Do I understand correctly you wrote your own converter?

Did you see we also have one in the Xamarin Community Toolkit you can use? I think that one works correctly :)

[ziomek64]

Hi @jfversluis ,
I think the problem here is not with converter at all, I don't seem to be getting any values from binded objects. It's not about my converter. I think the issue here is #9839 - seems like there are other things that are not working, which that person mentioned in the last comment. One of the things he mentioned is multibinding, and that thing is not working for me. And it seems that this bug existed for over a year now looking at the date from that issue

So I'm sorry that I kinda re-opened, because Initially I was looking for converter bugs. On the other hand how could I contribute as Xamarin Community Toolkit doesn't seem to be accepting more features anymore ? I have DateTimetoString converter and BooltoColor converter

[jfversluis]

OK, that makes sense. Was just trying to get to the root of this and because of that suggestion our converter. Because if that can work with the scenario you want it's obvious there isn't a bug in Forms :) but seems that there might be something you are running into.

If you are certain that the linked issue describes yours we might want to close this as a duplicate and track the other one

[ziomek64]

Well you can't be fully certain of something , but I am 99% certain this is the issue. I was looking for over two hours with someone for any typos in XAML and couldn't find anything. All the paths are set the same as in c# and are just not working. The only workaround now is to replace those parts with respective code in C#. This has to be fixed asap, I don't know if this issue exists in maui though. Haven't tried

[GalaxiaGuy]

#9839 seems to be about bindings that otherwise work but just aren't compiled. At least that how I understand the initial report:

Actual Behavior
Unfortunately, this type of binding is not compiled.