Why is DD4T markup rendered multiple times

Question

We noticed that when debugging our MVC5 DD4T application the page controller gets executed more than once. The same breakpoint is hit multiple times and all component presentations get rendered twice.

The markup returned is also funky... there are multiple doctype declarations and multiple and tags rendered.

I've scanned the code to see if something is calling the page controller multiple times - nothing. I've also checked my area registration and routes configs, and those are all in order.

What could be causing this?

Answer 1

The problem with multiple doctype declarations can be caused by some standard mvc view behaviour.

In your mvc project, you can define a _viewstart.cshtml file. In here, you specify the default mvc "master page" (called "layout page") to use. This layout page will be outputted around all of your views that don't specifiy a custom layout. you can specify a custom layout page per view by adding this piece of code on top of your view

{@layout="../your-custom-layout.cshtml"}

you can also specify not to use a layout by putting this

{@layout=null}

Now, as all of your component cshtml views are usually in one subfolder, an easy fix for this is to add a new _viewstart.cshtml file in the root of the components view folder containing this piece of code

@{
    Layout = null;
}

As a result, you can have your page views have a standard layout.cshtml masterpage, and all of your components have no master page.