Use given model nullability in razor pages #37510

Jupakabra · 2021-10-13T12:08:23Z

We are migrating our 5.0 project to 6.0-rc2 and noticed that RazorPage.Model was changed to always be nullable, even though model type in razor file is specified as not null. Because of this, we are getting thousands of compile time errors on any model access outside of asp-for expressions like asp-route-id="@Model.Id".

Describe the solution you'd like

Would it be possible to change it to TModel from TModel??
So we can tell the razor page if model is possibly null or not in the view?

@model MyModel?

Additional context

My guess is that razor doesn't parse nullable models in views, so it wasn't made that way because of that?

The text was updated successfully, but these errors were encountered:

pranavkm · 2021-10-14T17:34:56Z

In this particular case, it's valid for the model to be null i.e. you could do

// Index.cshtml
@model Person

// PersonController.cs
public IActionResult Get() => View(); // effectively View(model: null);

and the framework allows this. Introducing a null check in this code path would be a breaking change.

A possible workaround might be to introduce a base type for your view - https://docs.microsoft.com/en-us/aspnet/core/mvc/views/razor?view=aspnetcore-5.0#inherits that has the model property annotated for nullability differently and use that in your app. I'm leaving the issue open in case we'd like to try and address this in a later release.

pranavkm · 2021-10-14T17:35:01Z

FYI @DamianEdwards

ghost · 2021-10-14T17:35:11Z

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.

Jupakabra · 2021-10-14T18:09:58Z

Ye, we are aware that it's just an annotation disconnected from the back end. Was just thinking that matching razor model with your backend would result in better experience compared to just disabling nullability all together to avoid compile errors.

Good idea about the base view will try to do that 👍

Jupakabra · 2021-11-12T11:34:35Z

Tried using custom razor page model, but as expected razor doesn't handle it well today. For example using

@model TestModel?

Doesn't compile at all, because nullability context is disabled? Even though the project has it enabled.

cshtml.g.cs(10,5,10,6): error CS8669: The annotation for nullable reference types should only be used in code
within a '#nullable' annotations context. Auto-generated code requires an explicit '#nullable' directive in source.

Bartmax · 2021-12-03T13:01:35Z

I'm having this issue too. I believe it was wrong to annotate TModel as ?. A real blocker to upgrade to net6.
For me it's impossible to upgrade to NET6. I have 1983 views in one project only.

We need a way to fix (opt out of nullable razor models) with one liner at startup.

seangwright · 2021-12-22T22:00:25Z

This is a show-stopping breaking change if an app has <WarningsAsErrors>nullable</WarningsAsErrors>.

If an application has hundreds (or thousands) of Views, it's going to take awhile adding this 'unofficial' solution to get the app to compile again.

A possible workaround might be to introduce a base type for your view

Where was the planning for this feature? What was the official planned recommendation to resolve this issue for the many apps built before .NET 6.0?

Hundreds or thousands of errors after upgrading to .NET 6.0 and the best we have at the moment is "a possible workaround"?

🤦‍♂️🤦‍♂️🤦‍♂️🤦‍♂️

pranavkm · 2022-01-05T15:20:35Z

Thanks for the feedback. Addressing this is two parts -

a change in the to make [this non-nullable](https://github.com/dotnet/aspnetcore/blob/main/src/Mvc/Mvc.Razor/src/RazorPageOfT.cs#L18. It's fibbing a bit because the runtime doesn't enforce nullability for the model value, but it's definitely a lot less ergonomic this way.
update the Razor compiler to allow non-nullable models to be declared

My hope is to try and get these tackled as part of an upcoming VS release / .NET servicing release.

Contributes to dotnet#37510

Contributes to #37510

@model

Currently the Razor compiler suppresses nullable annotations within most generated code. https://github.com/dotnet/aspnetcore/issues/39360 tracks addressing this, but that would need a fair bit of work to get right. In the meantime, dotnet/aspnetcore#37510 is affecting a lot of users attempting to turn on nullability in their apps. The value of the `@model` directive appears as part of the class declaration for a Razor View: ```C# @model MyModel? // Results in #nullable disable internal sealed class _Views_Home_Index : RazorPage<MyModel?> // This will produce a warning since it's not within a nullable context ``` The `#nullable disable` precludes the ability of the user to be able to specify a nullable `model`. This change updates the compiler and generates the class declaration within a nullable context, as long as the C# version is recent enough to support nullability. The generated code now looks like: ```C# @model MyModel? // Results in ... #nullable restore // Use the nullability based on the project's global settings internal sealed class _Views_Home_Index : RazorPage<MyModel?> #nullable disable ``` In addition to the class declaration, we also need to generate the properties for `@inject` within a nullable context. This is because all views have an implicit `@inject IHtmlHelper<TModel>` where `TModel` is the model type.

@model

) Currently the Razor compiler suppresses nullable annotations within most generated code. https://github.com/dotnet/aspnetcore/issues/39360 tracks addressing this, but that would need a fair bit of work to get right. In the meantime, dotnet/aspnetcore#37510 is affecting a lot of users attempting to turn on nullability in their apps. The value of the `@model` directive appears as part of the class declaration for a Razor View: ```C# @model MyModel? // Results in #nullable disable internal sealed class _Views_Home_Index : RazorPage<MyModel?> // This will produce a warning since it's not within a nullable context ``` The `#nullable disable` precludes the ability of the user to be able to specify a nullable `model`. This change updates the compiler and generates the class declaration within a nullable context, as long as the C# version is recent enough to support nullability. The generated code now looks like: ```C# @model MyModel? // Results in ... #nullable restore // Use the nullability based on the project's global settings internal sealed class _Views_Home_Index : RazorPage<MyModel?> #nullable disable ``` In addition to the class declaration, we also need to generate the properties for `@inject` within a nullable context. This is because all views have an implicit `@inject IHtmlHelper<TModel>` where `TModel` is the model type.

pranavkm · 2022-01-14T22:24:15Z

This is fixed for the 6.0.2 release of the runtime and a compiler change that allows models to be declared as nullable would be available in 17.1 / 6.0.200 version of the .NET SDK. Thanks for all of your feedback!

kingmotley · 2022-02-08T20:41:36Z

@pranavkm Since runtime 6.0.2 seems to be included in the 17.0.6/6.0.102 SDK would those be appropriate, or is there additional work coming in 17.1.x/6.0.2xx?

dotnetshadow · 2022-02-08T21:42:24Z

I'm a little confused, I just updated my app to 6.0.2 but I'm still getting the analyser message:

Severity Code Description Project File Line Suppression State
Warning (active) CS8602 Dereference of a possibly null reference. Foo.Web d:\Programming\Code.....\Dashboard\Index.cshtml 70

<AnalysisMode>AllEnabledByDefault</AnalysisMode>

This is how I'm using it in index.cshtml

@model Foo.Dashboard.DashboardViewModel

<span class="counter-number-related text-capitalize">@("people".ToQuantity(Model.UserOnlineCount, ShowQuantityAs.None))</span>

Other people having the same issue:
https://stackoverflow.com/questions/69962866/pragma-8602-warning-in-razor-markup

pranavkm · 2022-02-08T22:12:00Z

So I just tried this with the 6.0.102 SDK installed and the runtime changes work - doing @Model.UserOnlineCount does not produce a nullable warning. I'm still unable to do @model TestModel? since that relies on a change in the 6.0.200 SDK which hasn't shipped.

Could you confirm that's the SDK your app is using to build? SDKs typically roll forward, so if you happen to have a 6.0.200 preview SDK installed side-by-side, it'll end up using that instead and not use these changes. You can confirm the SDK that is being used by running dotnet --info. You can also use a global.json to specify an exact SDK to use to build your project. You could consider using that until a RTM 6.0.200 rolls out:

Global.json contents:

{
  "sdk": {
    "version": "6.0.102"
  }
}

dotnetshadow · 2022-02-08T23:25:17Z

@pranavkm Thanks for getting back to me, have you set the analysis mode to <AnalysisMode>AllEnabledByDefault</AnalysisMode>

This is my runtime info

This is what I see in visual studio 2022

pranavkm · 2022-02-08T23:37:57Z

@dotnetshadow setting the AnalysisMode does not change the result for me. Do you see the same error if you build the app from the CLI? If you do, could I bother you to share msbuild binary logs by running dotnet msbuild /bl and including the MSBuild.binlog file. It might provide some hints about what's happening here.

Note that binlogs will capture ambient environment variables.

dotnetshadow · 2022-02-08T23:39:48Z

Do you see the same error if you build the app from the CLI?

Funny you should ask, I just tried that and I am getting the warning
To always get the error use: dotnet build --no-incremental

b\Features\Admin\Dashboard\Index.cshtml(70,97): warning CS8602: Dereference of a possibly null reference. [D:\Programming\Code\Company\StockWatch\src\Foo.Web\Foo.Web.csproj]

msbuild binary log
https://www.sendspace.com/file/r2y1cu

pranavkm · 2022-02-09T00:24:46Z

@dotnetshadow looks like the file was removed.

dotnetshadow · 2022-02-09T00:52:17Z

@dotnetshadow looks like the file was removed.

Sorry about that I uploaded to a new host
https://www.sendspace.com/file/r2y1cu

Diego-T · 2022-02-09T03:39:14Z

I was getting the same warning for razor files in Visual Studio and CLI build. dotnet --info also showed version 6.0.102 SDK.
Initially I installed it from Windows Update but after downloading and installing the SDK manually, the warning was gone.

Before reinstalling, when I used the "Go to definition" command over Model, I saw it still had the nullable annotation:

public TModel? Model { get; }

, but not after. I'm hoping that helps with the diagnostic.

pranavkm · 2022-02-09T03:44:18Z

Thanks @Diego-T. Looking at the build logs, it looks like it's compiling against the right assembly. Could you try installing the SDK from https://dotnet.microsoft.com/en-us/download/dotnet/6.0? It would help narrow down if this is a setup / installer issue.

Diego-T · 2022-02-09T03:50:31Z

@pranavkm That's what I did, I installed the SDK from that link and the warning was cleared. I'm on Windows 11 (22000.493) and used the x64 installer.
That compilation log is not mine though.

dotnetshadow · 2022-02-09T04:28:54Z

Thanks @Diego-T. Looking at the build logs, it looks like it's compiling against the right assembly. Could you try installing the SDK from https://dotnet.microsoft.com/en-us/download/dotnet/6.0? It would help narrow down if this is a setup / installer issue.

I did install from dot.net

.NET SDK (reflecting any global.json):
 Version:   6.0.102
 Commit:    02d5242ed7

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.19044
 OS Platform: Windows
 RID:         win10-x64
 Base Path:   C:\Program Files\dotnet\sdk\6.0.102\

Host (useful for support):
  Version: 6.0.2
  Commit:  839cdfb0ec

.NET SDKs installed:
  3.1.201 [C:\Program Files\dotnet\sdk]
  3.1.202 [C:\Program Files\dotnet\sdk]
  3.1.301 [C:\Program Files\dotnet\sdk]
  3.1.416 [C:\Program Files\dotnet\sdk]
  5.0.101 [C:\Program Files\dotnet\sdk]
  5.0.102 [C:\Program Files\dotnet\sdk]
  5.0.103 [C:\Program Files\dotnet\sdk]
  5.0.203 [C:\Program Files\dotnet\sdk]
  5.0.211 [C:\Program Files\dotnet\sdk]
  5.0.400 [C:\Program Files\dotnet\sdk]
  5.0.401 [C:\Program Files\dotnet\sdk]
  5.0.403 [C:\Program Files\dotnet\sdk]
  5.0.405 [C:\Program Files\dotnet\sdk]
  6.0.100 [C:\Program Files\dotnet\sdk]
  6.0.101 [C:\Program Files\dotnet\sdk]
  6.0.102 [C:\Program Files\dotnet\sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 3.1.20 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.21 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 3.1.22 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.12 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 5.0.14 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.0 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.1 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.AspNetCore.App 6.0.2 [C:\Program Files\dotnet\shared\Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.1.30 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.21 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 3.1.22 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.11 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.12 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 5.0.14 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.0 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.1 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.NETCore.App 6.0.2 [C:\Program Files\dotnet\shared\Microsoft.NETCore.App]
  Microsoft.WindowsDesktop.App 3.1.21 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 3.1.22 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.12 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 5.0.14 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.0 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.1 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]
  Microsoft.WindowsDesktop.App 6.0.2 [C:\Program Files\dotnet\shared\Microsoft.WindowsDesktop.App]

To install additional .NET runtimes or SDKs:
  https://aka.ms/dotnet-download

I will try to reinstall again

dotnetshadow · 2022-02-09T04:31:28Z

I was getting the same warning for razor files in Visual Studio and CLI build. dotnet --info also showed version 6.0.102 SDK. Initially I installed it from Windows Update but after downloading and installing the SDK manually, the warning was gone.

Before reinstalling, when I used the "Go to definition" command over Model, I saw it still had the nullable annotation:
public TModel? Model { get; }
, but not after. I'm hoping that helps with the diagnostic.

Hi @Diego-T Did you try compiling with the following? I initially didn't have the error but that's because dotnet build didn't try to rebuild properly
```dotnet build --no-incremental``

My 'Go to Definition' looks like this

Diego-T · 2022-02-09T04:39:26Z

@dotnetshadow I just tried with that flag --no-incremental and I don't get the warning. I can no longer reproduce the issue.

dotnetshadow · 2022-02-09T04:50:47Z

@dotnetshadow I just tried with that flag --no-incremental and I don't get the warning. I can no longer reproduce the issue.

Thanks @Diego-T @pranavkm. I just reinstalled dotnet-sdk-6.0.102-win-x64.exe seems to work now. Could of been a point in time thing. I rebooted and looks to be working now thanks for all your help guys. This issue can be closed

dotnetshadow · 2022-02-09T21:58:10Z

@pranavkm Just a note, I did notice the following peculiar issue.

Say you have as your model

// Index.cshtml
@model Person

Then later in the page you might have the following

// Index.cshtml
<p>@Model?.Age</p> // notice the ? here (even if it's by accident)
<p>@Model.Age</p>  // causes  Warning (active)	CS8602	Dereference of a possibly null reference.

pranavkm · 2022-02-09T22:31:40Z

@dotnetshadow that's a behavior for the C# compiler and works the same in regular C# code. You could follow up at https://github.com/dotnet/roslyn if you'd like further clarification.

Pilchie added the area-mvc Includes: MVC, Actions and Controllers, Localization, CORS, most templates label Oct 13, 2021

mkArtakMSFT assigned pranavkm Oct 14, 2021

mkArtakMSFT added this to the Discussions milestone Oct 14, 2021

pranavkm modified the milestones: Discussions, Backlog Oct 14, 2021

pranavkm removed their assignment Oct 14, 2021

mkArtakMSFT added the feature-razor-pages label Oct 14, 2021

pranavkm mentioned this issue Oct 26, 2021

MVC @model directive should respect the nullability of the type supplied #37844

Closed

pranavkm added the Priority:1 Work that is critical for the release, but we could probably ship without label Oct 28, 2021

pranavkm modified the milestones: Backlog, .NET 7 Planning Oct 28, 2021

mkArtakMSFT added enhancement This issue represents an ask for new feature or an enhancement to an existing one cost: M Will take from 3 - 5 days to complete triaged labels Oct 28, 2021

pranavkm mentioned this issue Nov 10, 2021

Incorrect nullability warning for razor files #38252

Closed

pranavkm mentioned this issue Dec 1, 2021

Nullable issue with RazorPage model #38762

Closed

pranavkm self-assigned this Jan 5, 2022

pranavkm added a commit to pranavkm/aspnetcore that referenced this issue Jan 5, 2022

Avoid declaring RazorPage<T>.Model as nullable by default

7a059cd

Contributes to dotnet#37510

This was referenced Jan 5, 2022

Avoid declaring RazorPage<T>.Model as nullable by default #39332

Merged

Use nullable context when declaring the class for Razor views dotnet/razor-compiler#29

Merged

pranavkm added a commit that referenced this issue Jan 7, 2022

Avoid declaring RazorPage<T>.Model as nullable by default (#39332)

57f283c

Contributes to #37510

pranavkm mentioned this issue Jan 12, 2022

Use nullable context when declaring the class for Razor views (#29) dotnet/razor-compiler#31

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pranavkm closed this as completed Jan 14, 2022

mkArtakMSFT modified the milestones: .NET 7 Planning, 6.0.2 Jan 27, 2022

PeterOrneholm mentioned this issue Feb 6, 2022

Update to .NET 6 ActiveLogin/ActiveLogin.Authentication#321

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pranavkm reopened this Feb 8, 2022

pranavkm closed this as completed Feb 9, 2022

mkArtakMSFT mentioned this issue Feb 17, 2022

VS Code: After installing .net 7.0, open a mvc6.0 project and encounter a warning: "Dereference of a possibly null reference." #40282

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G1Vh mentioned this issue Feb 21, 2022

Cant use asp-for tag helpers with nullable model #40327

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Use given model nullability in razor pages #37510

Use given model nullability in razor pages #37510

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Use given model nullability in razor pages #37510

Use given model nullability in razor pages #37510

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Describe the solution you'd like

Additional context

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