Finding Layout Views in ASP.NET Core
The biggest change in handling Views in ASP.NET Core is that you can now have more than one _Layout.cshtml file in your project and your Views will pick the one "closest to them." In ASP.NET MVC, you set a View's Layout property to the full path name of the Layout file to be used, like this:
@{
Layout = "~/Views/Shared/_Layout.cshtml";
}
In ASP.NET Core, you can set the Layout property to as little as the name of the file. This, for example, is perfectly OK:
@{
Layout = "_Layout";
}
When you don't provide a path name to your layout View, ASP.NET Core first goes looking for the layout in the same folder as the View that requested it. Only when ASP.NET Core doesn't find a file with the right name "locally" does ASP.NET Core go on to the /Shared folder to find a "global" layout View.
This means that you can set the Layout property in your _ViewStart.cshtml file to a default value "_Layout" but have Views in different folders pick up different layouts. This can mean a lot fewer Views having to override that default setting for the Layout property: If all the Views for a Controller share a layout View, you can just put that layout View in the Views folder for that Controller's Views.
Posted by Peter Vogel on 04/04/2019