Layout namespace for Blazor Web Apps

[bmeenehan]

Description

It is clear how to make a custom layout, using LayoutComponentBase and the @Body directive.
However, it is not mentioned that an @using directive is also required to use the @layout directive on a page.

Page URL

https://learn.microsoft.com/en-us/aspnet/core/blazor/components/layouts?view=aspnetcore-8.0

Content source URL

https://github.com/dotnet/AspNetCore.Docs/blob/main/aspnetcore/blazor/components/layouts.md

Document ID

58e0022a-ac6c-9bf8-380a-40b7d068a887

Article author

@guardrex

[github-actions]

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[guardrex]

Hello @bmeenehan ... Be more specific about the exact layout file location because it shouldn't be required if the layout is discoverable from the Layout folder.

Although, it is true that in a Blazor Web App there is an @using statement for the Components folder, which contains the Layout folder. That's present by default ... and it's also true that the latest Blazor router markup (RouteView component) references the layout by folder name ...

<RouteView RouteData="@routeData" DefaultLayout="@typeof(Layout.MainLayout)" />

Whereas for Blazor Server (of yesteryear now), the layouts were in the Shared folder, so that's when no qualification on the namespace was required ...

<RouteView RouteData="@routeData" DefaultLayout="@typeof(MainLayout)" />

Let me think about how to address this. I'm now leaning in your direction here. However, I think a blanket statement that will cover all scenarios, including Blazor WASM, makes sense. There's been quite a bit of churn, and trying to version this one is a bit much given that it's a general principle ... you just have to have the namespace available of any object that you intend to use. I guess for the example I should make a @using in the _Imports file and just version it >=8.0.

Interesting ... the Layout folder is present in the _Imports file of a Blazor WASM app under 8.0, but it isn't in a BWA. I don't like when there's a delta like this in the framework because it results in inconsistent building blocks for the two app types that docs have to call out and version.

[bmeenehan]

Good day Luke, Thank you for your prompt response. My custom layout is in the Layout folder, alongside the MainLayout.razor file. But I got the error "The type or namespace name 'CustomLayout' could not be found", when adding the @layout directive to a page. I resolved the error by adding @using [ProjectName].Components.Layout in my _Imports.razor file. Is that unexpected behaviour? I'm entirely new to Blazor and still finding my way around.

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On Thu, 30 Nov 2023 at 13:36, Luke Latham ***@***.***> wrote: Hello @bmeenehan <https://github.com/bmeenehan> ... Be more specific about the exact layout file location because it shouldn't be required if the layout is discoverable from the Layout folder. Blazor finds layouts in the Layout folder by default. — Reply to this email directly, view it on GitHub <#31170 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ADLT7CMCCIMQOEBW222ZHGLYHBVUBAVCNFSM6AAAAABAAULR7WVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQMZTGU4TKOJTGI> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[guardrex]

Can you find the layout without using the namespace in your _Imports file by referecing it the same way at the project template with Layout. supplied ...

<RouteView RouteData="@routeData" DefaultLayout="@typeof(Layout.{CUSTOM LAYOUT})" />

[guardrex]

I'm going to open a product unit issue on this. I feel like they should've give the Layout folder an entry in the _Imports file. They might have had a reason not to do it, but they'll tell us that on the issue I'm about to open.