Clarification on whether the new Blazor SSR validation JS supports MVC/Razor Pages markup as well?

[itsmecurtis]

I’m looking at the Blazor SSR validation work in #51040 / #66420 / #66441.

The PR description calls out that the server renders the same data-val-* attributes used by MVC/Razor Pages, and some issue discussion before implementation suggested the validation library should work for MVC and Razor Pages as well as Blazor SSR, but in the .NET 11 release notes this is framed entirely as being about Blazor SSR.

Any clarification would be helpful! Thanks!

[zuhairhalawa]

Not with the current implementation. The data-val-* rendering described in #66441 and #66420 is the Preview 5 design. #67324 (merged on 16 Jul 2026, milestone 11.0-preview7 and linked from the Preview 7 release notes) replaced it: rules are no longer rendered as data-val-* attributes on each input. Instead each static SSR form gets a single <blazor-client-validation-data data-rules="..."> element carrying the rules as JSON, and the [data-val=true] scanner is gone. At v11.0.0-rc.2 the adapter in src/Components/Web.JS/src/Validation/Adapters/BlazorAdapter.ts only ingests that element, and the server side (ClientValidationData in Components/Web) renders it only for an EditForm whose EditContext was activated by DataAnnotationsValidator.

So the data-val, data-val-required, ... attributes that MVC/Razor Pages tag helpers emit are not read by this script, and the Preview 5 and Preview 7 release notes describe the feature only for Blazor SSR forms. MVC/Razor Pages client validation is still jquery-validation plus jquery.validate.unobtrusive (for example the Identity UI's _ValidationScriptsPartial.cshtml at that tag). What still overlaps is only the message and summary hooks (data-valmsg-for, data-valmsg-replace, data-valmsg-summary).

[zuhairhalawa]

If this answers your question about MVC/Razor Pages support, could you mark it as the answer so it is easy for others to find?