[Feature] x:Bind should support general string indexers without interface in C#

Describe the bug The documentation for x:Bind here in the ‘path to the function’ section specifies:

The path to the function is specified like other property paths and can include dots (.), indexers or casts to locate the function.

However, it appears that non-integer based indexers, e.g. strings, are not supported?

I was trying to bind directly to a Graph function with the Windows Community Toolkit’s GraphPresenter:

RequestBuilder="{x:Bind providers:ProviderManager.Instance.GlobalProvider.Graph.Teams['<guid here>'].Channels['<guid thing here>'].Messages, Mode=OneWay}"

As these classes use string indexers to build the query to the Graph, E.g.

ITeamRequestBuilder this[string id] { get; }

However VS tells me in the x:Bind expression that I have provided an “invalid index value” and “WMC1110: Invalid binding path … Unexpected array indexer”.

Expected behavior I would have expected string indexers to work just as I can pass them into function parameters with x:Bind in single-quotes.

Version Info NuGet package version: WUX

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
May 2020 Update (19041)	Yes
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

[JeanRoca]

Alright I see thank you for the insight. I will go ahead and place it in the backlog, but can’t quite guarantee an ETA for it yet. I will leave the issue open.

[StephenLPeters]

@StephenLPeters I understand that this was not intended as designed originally, but this is still a feature request.

Is there a reason the collection needs to be mutable to support this feature? Can we get a few more details here? I know it’ll still need WinUI 3 to be fixed most likely in the future, if possible.

Thanks!

Sorry the triage team interpretated the conversation differently. We can reuse this as a feature proposal