In certain cases, we might end up reusing snippets of HTML, such as forms, on different pages. We can also use these “partials” to break up more complex pages into smaller sections. This is another way to reduce duplication of common markup content across different files and keep our code DRY. “D.R.Y” (Don’t Repeat Yourself), is a software development principle, the main aim of which is to reduce the repetition of code.

Partial file names also begin with an underscore in their name (through convention). And in order to render the content we can use the following syntax in our content page:

<partial name="_PartialName" />

Where name refers to the filename of the partial.

Let’s look at an example:

Picture an application with the following folder structure:

Razor App
│   Startup.cs
│   Program.cs
│   RazorApp.sln
│   ...
│
└───Pages
│   │   _ViewStart.cshtml
│   │   MyPage.cshtml
│   │   MyPage.cshtml.cs
│   │  ...
│   │
│   └───Shared
│       │   _Layout.cshtml
│       │   _MyPartial.cshtml.
│       │   ...
│   
└───Properties

If our partial has the following content:

_MyPartial.cshtml:

<div>Here's some content from a partial!</div>

We can use the partial in a separate page as follows:

MyPage.cshtml:

<div>
  <h1>Welcome to My Page!</h1>
  <partial name="_MyPartial"/>
</div>

Similarly to Layouts, Razor Pages will search all registered partial locations for a file with the supplied name and if it finds it, it will render its content resulting in:

<div>
  <h1>Welcome to My Page!</h1>
  <div>Here's some content from a partial!</div>
</div>