Aspnetcore.docs: 3.0 Migration Discuss RazorPages AllowAreas option

[ardalis]

[EDIT by guardrex to add the metadata for the migration topic]

In the 2.2 -> 3.0 Migration guide, cover what do with this:

                .AddRazorPagesOptions(options =>
                {
                    options.Conventions.AuthorizePage("/Basket/Checkout");
                    options.AllowAreas = true; // THIS LINE
                })

The line noted above triggers this error in 3.0 latest preview:

Error | CS1061 | 'RazorPagesOptions' does not contain a definition for 'AllowAreas' and no accessible extension method 'AllowAreas' accepting a first argument of type 'RazorPagesOptions' could be found (are you missing a using directive or an assembly reference?)

I don't know what nuget package, if any, can be added to fix this.

---

Document Details

⚠ Do not edit this section. It is required for docs.microsoft.com ➟ GitHub issue linking.

• ID: 76f39eec-9dd1-6167-56ec-47b26e0b5063
• Version Independent ID: f9f2b0f3-01eb-cf58-8767-194fe0fc0e44
• Content: Migrate from ASP.NET Core 2.2 to 3.0 Preview
• Content Source: aspnetcore/migration/22-to-30.md
• Product: aspnet-core
• Technology: aspnetcore-migration
• GitHub Login: @tdykstra
• Microsoft Alias: tdykstra

[guardrex]

Thus far, I see it was removed here :point_right: https://github.com/aspnet/AspNetCore/commit/f113a20dfd9d0c7c991e425fd8000ed6b64d19a5#diff-5c43af172dc698a7587dca36319961fc

... but is the default for areas to allow them? ... are u saying if you remove that and run it that the areas aren't allowed by default?

[serpent5]

AllowAreas is a compatibility switch. With 3.0 being a breaking change, Areas are "allowed" out of the box, so options.AllowAreas = true; can be dropped.

[guardrex]

Nice one @serpent5 ... I saw a passing remark on it but didn't have confirmation from the commit that dropped it.

[ardalis]

I'd mention that it can be removed in the migration doc. Otherwise it's going to be a compiler error customers are going to spend time trying to track down (instead of just deleting that line).

[guardrex]

@Rick-Anderson should add it, as he's managing the topic.

[pranavkm]

@ardalis the feature is on by default (and there isn't a way to disable it). It was added as a compat switch for apps migrating from 2.1 -> 2.2 since it introduced a breaking behavior change. Removing it in 3.0 would be the right thing to do.

[Rick-Anderson]

@pranavkm I'll update Compatibility version and in the release notes mention the compatibility features have been removed for 3.0

[ardalis]

@pranavkm Thanks! I'm fine with removing it of course. My issue was that in the course of upgrading an app from 2.2 to 3.0 I had a bunch of missing references (due mostly to things coming out of Microsoft.AspNetCore.App) and this error blended in with those. So I spent at least 20 minutes trying to figure out which Nuget package I had to add to fix the error. Including a note that it can be removed in the migration guide will hopefully save others (and probably future me) from this frustration.

[Rick-Anderson]

AllowAreas is listed in github.com/aspnet/Announcements label:"Breaking change" in issue Breaking API changes in Antiforgery, Cors, Diagnostics, Mvc, and Routing #387

The migration guide has a link to the breaking issues. I don't want to repeat that info in the migration guide. Folks who hit this google will find this issue. If enough hit it, I'll consider adding it to the migration guide.