hugo/docs/content/en/functions/partials/Include.md

title	description	categories	keywords	action	aliases
partials.Include	Executes the given partial template, optionally passing context. If the partial template contains a return statement, returns the given value, else returns the rendered output.			aliases related returnType signatures partial functions/go-template/return functions/partials/IncludeCached functions/go-template/template methods/page/Render any partials.Include NAME [CONTEXT]	/functions/partial

Without a return statement, the partial function returns a string of type template.HTML. With a return statement, the partial function can return any data type.

In this example we have three partial templates:

layouts/
└── partials/
    ├── average.html
    ├── breadcrumbs.html
    └── footer.html

The "average" partial returns the average of one or more numbers. We pass the numbers in context:

{{ $numbers := slice 1 6 7 42 }}
{{ $average := partial "average.html" $numbers }}

The "breadcrumbs" partial renders breadcrumb navigation, and needs to receive the current page in context:

{{ partial "breadcrumbs.html" . }}

The "footer" partial renders the site footer. In this contrived example, the footer does not need access to the current page, so we can omit context:

{{ partial "breadcrumbs.html" }}

You can pass anything in context: a page, a page collection, a scalar value, a slice, or a map. For example:

{{ $student := dict 
  "name" "John Doe" 
  "major" "Finance"
  "gpa" 4.0
}}
{{ partial "render-student-info.html" $student }}

Then, within the partial template:

<p>{{ .name }} is majoring in {{ .major }}. Their grade point average is {{ .gpa }}.</p>

To return a value from a partial template, it must contain only one return statement, placed at the end of the template:

{{ $result := "" }}
{{ if math.ModBool . 2 }}
  {{ $result = "even" }}
{{ else }}
  {{ $result = "odd" }}
{{ end }}
{{ return $result }}

See details.