Blazor: Record Type binding and validation for EditContext/EditForm

[braidenstiller]

Is your feature request related to a problem? Please describe.

Please consider binding and model validation in Blazor with record types. Currently when using the EditForm/EditContext it requires a model with mutable properties for input binding. Having the EditForm/EditContext bind to a record type and emit a new instance with modified state would allow for client-side functionality like state machines, state rewinding and fast-forwarding, mutation batching and other workflows which benefit from immutable state. This functionality and workflow would be similar to the MVC 5 record type binding which allows for form fields binding, field validation and model validation.

https://docs.microsoft.com/en-us/aspnet/core/release-notes/aspnetcore-5.0?view=aspnetcore-5.0

Describe the solution you'd like

A simple and idiomatic way to bind to record types similar to the current binding syntax. Understandably the current bind syntax may not be suitable as the field would have to emit a new record instance with the changes, then alert the EditForm/EditContext to update the bound Model property, or let the user handle it emit an event to propagate the changes up (or a combination of both).

[pranavkm]

Thanks for your suggestion. Blazor expects it's models to be editable. Adding support for immutable types isn't high on our priority. at this point. We'll reconsider this issue if we get a lot of community feedback. Parking this in the backlog for now.

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[jp-gouigoux]

Just giving a +1 here for this feature, as it would allow using Flux pattern without having to compromise on a mutable state, which is the main principle for code stability. Changing the behaviour is possible with onchange events where we can catch the event and adjust the property by passing a new record, but this is not possible to do so on two-way binding or with oninput events. If not possible to send a modified state, could you - as a backup scenario - make it possible to catch the event and set the new record by user code, without disabling the binding (which, for now, does not work if we change the record). I can provide some test code if needed.

Thanks for contacting us.

We're moving this issue to the .NET 8 Planning milestone for future evaluation / consideration. We would like to keep this around to collect more feedback, which can help us with prioritizing this work. We will re-evaluate this issue, during our next planning meeting(s).
If we later determine, that the issue has no community involvement, or it's very rare and low-impact issue, we will close it - so that the team can focus on more important and high impact issues.
To learn more about what to expect next and how this issue will be handled you can read more about our triage process here.

[mkArtakMSFT]

As part of this issue, we will need to also make sure that this is not Blazor specific and that record types also work fine for model binding in MVC.