Method Signature for IsValid is wrong

[spersov]

The documentation for implementing IsValid for custom attributes has an incorrect signature. The signature for IsValid shown here has object? value whereas the example does not. The return type is also nullable.

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Document Details

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• ID: 0156ffc3-47ac-d5da-fbc2-9ff5018b071b
• Version Independent ID: 615db388-a244-41f7-21b5-a4085d9ed479
• Content: Model validation in ASP.NET Core MVC
• Content Source: aspnetcore/mvc/models/validation.md
• Product: aspnet-core
• Technology: aspnetcore-mvc
• GitHub Login: @Rick-Anderson
• Microsoft Alias: riande

[guardrex]

Hello @spersov ... Because ASP.NET Core is adopting nullable ref types for 6.0 (and into the future), we're going to be seeing a ton of these nullability warnings for quite a while. A vast number of doc code examples are going to toss warnings ⚠️ into build output. For example, I just updated the EF Core-Blazor Server sample to address them, and there were about 50 (Yikes!) in just that one sample. There are over 100 doc sample apps and thousands of code examples total, both pulled from the sample apps and inline examples in doc text. I think that it's going to take years to sort them all out ⛏️🚧.

@Rick-Anderson ... We might want to have a saved GH answer on this one given that there might be quite a few reader remarks coming in on this. If you devise some text, I'll save and use it from here, too. I'll keep an 👁️ out and an 👂 open. Here are the cross-links in a cut-'n-paste for the Nullable property and a great resource for devs updating their apps (includes #pragma guidance) ...

* [Nullable reference types (C# reference): Setting the nullable context](https://docs.microsoft.com/dotnet/csharp/language-reference/builtin-types/nullable-reference-types#setting-the-nullable-context)
* [Update a codebase with nullable reference types to improve null diagnostic warnings (C# Guide)](https://docs.microsoft.com/dotnet/csharp/nullable-migration-strategies)

[guardrex]

@Rick-Anderson ... I've worked up a GH saved reply on this. I think there will be quite a few asks ... guessing ... because so many samples and cut-'n-paste examples are going to trigger null-state checking. I'll keep an 👁️ here and 👂 open for your feedback to further update it.

btw ---- How do you want such issues labelled before they're closed? ... docs-experience? product-question? support-request? Discussion?

Draft GH saved reply (with a cut-'n-paste code version below) ...

Content

ASP.NET Core 6.0 with C# 10 embraces nullable reference types (NRTs) and the .NET compiler's null-state static analysis, which were first available with the release of C# 8. Compiler nullability warnings will be common using the documentation examples and sample apps until they're updated, which is an on-going process.

Prior to our doc example and sample updates, compiler null-state warnings can either be ignored or serve as a guide for the developer to update an example or sample app locally. You can also disable the compiler's null-state static analysis by setting Nullable to disable in the project file, which we only recommend for doc examples and samples that you're testing and learning from. We don't recommended disabling null-state checking in your production projects.

For more information on NRTs, the Nullable property, and updating apps (including #pragma guidance), see the following resources in the C# documentation ...

• Nullable reference types
• Nullable reference types (C# reference)
• Learn techniques to resolve nullable warnings
• Update a codebase with nullable reference types to improve null diagnostic warnings
• Attributes for null-state static analysis

Code version

ASP.NET Core 6.0 with C# 10 embraces nullable reference types (NRTs) and the .NET compiler's null-state static analysis, which were first available with the release of C# 8. Compiler nullability warnings will be common using the documentation examples and sample apps until they're updated, which is an on-going process.

Prior to our doc example and sample updates, compiler null-state warnings can either be ignored or serve as a guide for the developer to update an example or sample app locally. You can also disable the compiler's null-state static analysis by setting `Nullable` to `disable` in the project file, which we only recommend for doc examples and samples that you're testing and learning from. **_We don't recommended disabling null-state checking in your production projects._**

For more information on NRTs, the `Nullable` property, and updating apps (including `#pragma` guidance), see the following resources in the C# documentation ...

* [Nullable reference types](https://docs.microsoft.com/dotnet/csharp/nullable-references)
* [Nullable reference types (C# reference)](https://docs.microsoft.com/dotnet/csharp/language-reference/builtin-types/nullable-reference-types)
* [Learn techniques to resolve nullable warnings](https://docs.microsoft.com/dotnet/csharp/nullable-warnings)
* [Update a codebase with nullable reference types to improve null diagnostic warnings](https://docs.microsoft.com/dotnet/csharp/nullable-migration-strategies)
* [Attributes for null-state static analysis](https://docs.microsoft.com/dotnet/csharp/language-reference/attributes/nullable-analysis)

[guardrex]

I'm placing a blurb in the Blazor Project Structure topic on this with the cross-links at ...

#23504

The updates to 6.0 Blazor example code will occur transparently: I'll either update all of them for 6.0 docs in December or early 2022 in one shot. The work will be tracked for now by the Blazor 6.0 tracking issue.

[Rick-Anderson]

btw ---- How do you want such issues labelled before they're closed? ... docs-experience? product-question? support-request? Discussion?

This deserves a new label, "NULL-experience" or Null.

[guardrex]

That's not a more traditional won't-fix? I've never seen "null" in a GH label for this. Not saying tho that it's better either way, per se, but readers will certainly understand won't-fix ... or something like that.

[guardrex]

They recommend it without punctuation in their default use ...

https://docs.github.com/en/issues/using-labels-and-milestones-to-track-work/managing-labels#about-default-labels

However, we use punctuation, so won't-fix matches what's in use here.

[Rick-Anderson]

but readers will certainly understand won't-fix ... or something like that.

They rarely pay attention to labels, the label is for us.

[guardrex]

@Rick-Anderson ... DR asked for a single, general remark for the whole framework. I removed the NRT section from the Blazor docs. It's now live in the migration topic at ...

https://docs.microsoft.com/aspnet/core/migration/50-to-60#nullable-reference-types-nrts-and-net-compiler-null-state-static-analysis

AFAIK, this issue is resolved. Well ... except for about 10,000 NRT warnings! 🙈😄