Add cascading parameters for theme views

[justinyoo]

Purpose

• Switch theme view base types (IndexViewBase, PageViewBase, PostViewBase, NotFoundViewBase) from direct [Parameter] inputs to [CascadingParameter] so themes can receive context consistently via the layout.
• Update the default theme layout to provide these values via CascadingMainLayoutBase.
• Adjust rendering/generation pipeline to align with the cascading approach and add/extend unit tests.

Does this introduce a breaking change?

[x] Yes
[ ] No

Pull Request Type

What kind of change does this Pull Request introduce?

[ ] Bugfix
[x] New feature
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

README updated?

The top-level readme for this repo contains a link to each sample in the repo. If you're adding a new sample did you update the readme?

[x] Yes
[ ] No
[ ] N/A

How to Test

• Get the code

git clone https://github.com/getscissorhands/Scissorhands.NET
cd Scissorhands.NET
git checkout feat/cacading-parameters

• Test the code

dotnet test test/ScissorHands.Theme.Tests/ScissorHands.Theme.Tests.csproj -c Release
dotnet test test/ScissorHands.Web.Tests/ScissorHands.Web.Tests.csproj -c Release

What to Check

Verify that the following are valid

• Theme views can access Document(s), Plugins, Theme, and Site via cascading parameters when rendered under the main layout.
• Default theme renders pages/posts/404 without requiring these values as direct component attributes.

Other Information

• Theme authors may need to wrap their layout with CascadingMainLayoutBase (or otherwise provide equivalent cascading values) to populate the view base properties.

[Copilot]

Pull request overview

This PR introduces a breaking architectural change that switches theme view base types from direct [Parameter] bindings to [CascadingParameter] bindings, enabling theme components to receive context values (Documents, Document, Plugins, Theme, Site) via a cascading layout wrapper instead of explicit component attributes.

Key Changes:

• Introduced a builder pattern for application initialization (ScissorHandsApplicationBuilder) replacing the generic ScissorHandsApplication<T1, T2, T3, T4, T5> with a non-generic version that uses reflection
• Converted all theme view base class properties from [Parameter] to [CascadingParameter] and made them nullable
• Added CascadingMainLayoutBase wrapper component to provide cascading values throughout the component tree
• Refactored document rendering to use parallel processing with Task.WhenAll

Reviewed changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
src/ScissorHands.Web/ScissorHandsApplicationBuilder.cs	New builder class providing fluent API for configuring layouts with validation
src/ScissorHands.Web/ScissorHandsApplication.cs	Refactored to non-generic implementation using reflection to invoke BuildAsync with runtime types
src/ScissorHands.Web/Renderers/ComponentRenderer.cs	Updated to filter out cascading parameters from component attributes to prevent duplicate bindings
src/ScissorHands.Web/Generators/StaticSiteGenerator.cs	Refactored document rendering to use parallel processing and extracted rendering logic into separate methods
src/ScissorHands.Theme/IndexViewBase.cs	Changed Documents, Plugins, Theme, Site from Parameter to CascadingParameter and made nullable
src/ScissorHands.Theme/PageViewBase.cs	Changed Document, Plugins, Theme, Site from Parameter to CascadingParameter and made nullable
src/ScissorHands.Theme/PostViewBase.cs	Changed Document, Plugins, Theme, Site from Parameter to CascadingParameter and made nullable
src/ScissorHands.Theme/NotFoundViewBase.cs	Changed Document, Plugins, Theme, Site from Parameter to CascadingParameter and made nullable
src/ScissorHands.Web/themes/default/MainLayout.razor	Wrapped body with CascadingMainLayoutBase to provide cascading values
src/ScissorHands.Web/themes/default/IndexView.razor	Updated to use null-conditional operators for Documents property
src/ScissorHands.Web/themes/default/PageView.razor	Updated to use null-conditional and null-forgiving operators for Document.Html
src/ScissorHands.Web/themes/default/PostView.razor	Updated to use null-conditional and null-forgiving operators for Document.Html
src/ScissorHands.Web/themes/default/NotFoundView.razor	Updated null-checking logic for Document.Html property
src/ScissorHands.Web/themes/default/_Imports.razor	Added using directive for ScissorHands.Theme namespace
test/ScissorHands.Theme.Tests/IndexViewBaseTests.cs	Updated tests to expect null Documents and added test for cascading parameter binding
test/ScissorHands.Theme.Tests/PageViewBaseTests.cs	Updated tests to expect null Document and added test for cascading parameter binding
test/ScissorHands.Theme.Tests/PostViewBaseTests.cs	Updated tests to expect null Document and added test for cascading parameter binding
test/ScissorHands.Theme.Tests/NotFoundViewBaseTests.cs	Updated tests to expect null Document and added test for cascading parameter binding
test/ScissorHands.Web.Tests/Renderers/ComponentRendererCascadingParametersTests.cs	New test file verifying cascading parameters flow through layout without being passed as component attributes
README.md	Updated usage example to demonstrate new builder pattern API

Comments suppressed due to low confidence (1)

src/ScissorHands.Web/themes/default/NotFoundView.razor:15

• The null-checking logic for Document is incorrect. At line 5, string.IsNullOrWhiteSpace(Document?.Html) == true will be true if Document is null OR if Document.Html is null/whitespace. However, in the else branch at line 15, the code accesses Document.Html without a null-conditional operator or null-forgiving operator.

If Document is null, line 15 will throw a NullReferenceException. The code should use Document?.Html! or add an additional null check for Document itself.

    @if (string.IsNullOrWhiteSpace(Document?.Html) == true)
    {
        <article>
            <h1>404 - Not Found</h1>
            <p>The page you are looking for does not exist.</p>
        </article>
    }
    else
    {
        <article>
            @((MarkupString)Document.Html)

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[Copilot]

@justinyoo I've opened a new pull request, #75, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

@justinyoo I've opened a new pull request, #76, to work on those changes. Once the pull request is ready, I'll request review from you.

[Copilot]

@justinyoo I've opened a new pull request, #77, to work on those changes. Once the pull request is ready, I'll request review from you.