Can I select the layout to use for a page with Wyam? - wyam

Question

I'm working on a theme for Wyam and I'm wondering if there's a way to set the layout that should be used in the markdown file for a particular page. As far as I have seen so far, it seems that each page created with markdown uses _Layout.cshtml
To be more specific. I'm creating an "about.md" page, which has a different layout then then other (default) pages.
So what I would like to do is use metadata to select the layout. For example
Layout: _About.cshtml
or
Layout: _About
Is this possible with Wyam?

Answer 1

In A Razor File
Pages in the Wyam recipes (I'm assuming you're using either the blog or docs recipe) are processed by Razor. The use of a _Layout.cshtml is by convention in the recipe, but alternate layouts can be specified using standard Razor syntax. You can do so by placing the following at the top of the about page .cshtml file (under your front matter):
#{
Layout = "_About.cshtml";
}
In A Markdown File
Markdown files are also processed by the Razor engine, so the technique above would work if it weren't for the Markdown processor escaping the # symbol. There's really no good way around that, and the simple answer to your question is you can't specify an alternate layout for a Markdown file.
However, one of the advantages of using a code-driven generator like Wyam is that you have a lot of control. In this case, you can replace the RenderPages pipeline with one that will do exactly what you want. Add the following to your wyam.config file:
int index = Pipelines.IndexOf(Blog.RenderPages);
Pipelines.Remove(Blog.RenderPages);
Pipelines.Insert(index, Blog.RenderPages,
(IPipeline)new Wyam.Web.Pipelines.RenderPages(
Blog.RenderPages,
new Wyam.Web.Pipelines.RenderPagesSettings
{
Pipelines = new string[] { "Pages" },
Layout = (doc, ctx) => doc.String("Layout", "/_Layout.cshtml")
}));
Then you'll be able to add a "Layout" value as front matter exactly like you wrote in your question.
This was a good idea in general, so I've also opened an issue to add this behavior to the recipe by default.