Base Templates and Blocks

The block keyword allows you to define the outer shell of your pages’ one or more master template(s) and then fill in or override portions as necessary.

Base Template Lookup Order

The lookup order for base templates is as follows:

/layouts/section/<TYPE>-baseof.html
/themes/<THEME>/layouts/section/<TYPE>-baseof.html
/layouts/<TYPE>/baseof.html
/themes/<THEME>/layouts/<TYPE>/baseof.html
/layouts/section/baseof.html
/themes/<THEME>/layouts/section/baseof.html
/layouts/_default/<TYPE>-baseof.html
/themes/<THEME>/layouts/_default/<TYPE>-baseof.html
/layouts/_default/baseof.html
/themes/<THEME>/layouts/_default/baseof.html

Variables are denoted by capitalized text set within <>. Note that Hugo’s default behavior is for type to inherit from section unless otherwise specified.

Example Base Template Lookup Order

As an example, let’s assume your site is using a theme called “mytheme” when rendering the section list for a post section. Hugo picks layout/section/post.html as the template for rendering the section. The {{define}} block in this template tells Hugo that the template is an extension of a base template.

Here is the lookup order for the post base template:

/layouts/section/post-baseof.html
/themes/mytheme/layouts/section/post-baseof.html
/layouts/post/baseof.html
/themes/mytheme/layouts/post/baseof.html
/layouts/section/baseof.html
/themes/mytheme/layouts/section/baseof.html
/layouts/_default/post-baseof.html
/themes/mytheme/layouts/_default/post-baseof.html
/layouts/_default/baseof.html
/themes/mytheme/layouts/_default/baseof.html

Define the Base Template

The following defines a simple base template at _default/baseof.html. As a default template, it is the shell from which all your pages will be rendered unless you specify another *baseof.html closer to the beginning of the lookup order.

layouts/_default/baseof.html


<!DOCTYPE html>
<html>
  <head>
    <meta charset="utf-8">
    <title>{{ block "title" . }}
      <!-- Blocks may include default content. -->
      {{ .Site.Title }}
    {{ end }}</title>
  </head>
  <body>
    <!-- Code that all your templates share, like a header -->
    {{ block "main" . }}
      <!-- The part of the page that begins to differ between templates -->
    {{ end }}
    {{ block "footer" . }}
    <!-- More shared code, perhaps a footer but that can be overridden if need be in  -->
    {{ end }}
  </body>
</html>

Override the Base Template

From the above base template, you can define a default list template. The default list template will inherit all of the code defined above and can then implement its own "main" block from:

layouts/_default/list.html


{{ define "main" }}
  <h1>Posts</h1>
  {{ range .Data.Pages }}
    <article>
      <h2>{{ .Title }}</h2>
      {{ .Content }}
    </article>
  {{ end }}
{{ end }}

This replaces the contents of our (basically empty) “main” block with something useful for the list template. In this case, we didn’t define a "title" block, so the contents from our base template remain unchanged in lists.

Code that you put outside the block definitions can break your layout. This even includes HTML comments. For example:

<!-- Seemingly harmless HTML comment..that will break your layout at build -->
{{ define "main" }}
...your code here
{{ end }}

See this thread from the Hugo discussion forums.

The following shows how you can override both the "main" and "title" block areas from the base template with code unique to your default single page template:

layouts/_default/single.html


{{ define "title" }}
  <!-- This will override the default value set in baseof.html; i.e., "{{.Site.Title}}" in the original example-->
  {{ .Title }} – {{ .Site.Title }}
{{ end }}
{{ define "main" }}
  <h1>{{ .Title }}</h1>
  {{ .Content }}
{{ end }}