hugo/docs/content/functions/default.md

title	description	qref	godocref	date	publishdate	lastmod	categories	menu	toc	signature	workson	hugoversion	relatedfuncs	deprecated	draft	aliases	needsexamples
default	Allows setting a default value that can be returned if a first value is not set.	Returns a default value if a value is not set when checked.		2017-02-01	2017-02-01	2017-02-01	functions	docs parent functions		default DEFAULT INPUT				false	false	/functions/default/	false

default checks whether a given value is set and returns a default value if it is not. Set in this context means different things depending on date type:

• non-zero for numeric types and times
• non-zero length for strings, arrays, slices, and maps
• any boolean or struct value
• non-nil for any other types

default function examples reference the following content page:

{{% code file="content/posts/default-function-example.md" %}}

---
title: Sane Defaults
seo_title:
date: 2017-02-18
font:
oldparam: The default function helps make your templating DRYer.
newparam:
---

{{% /code %}}

default can be written in more than one way:

{{ index .Params "font" | default "Roboto" }}
{{ default "Roboto" (index .Params "font") }}

Both of the above default function calls return Roboto.

A default value, however, does not need to be hard coded like the previous example. The default value can be a variable or pulled directly from the front matter using dot notation:

{{% code file="variable-as-default-value.html" nocopy="true" %}}

{{$old := .Params.oldparam }}
<p>{{ .Params.newparam | default $old }}</p>

{{% /code %}}

Which would return:

<p>The default function helps make your templating DRYer.</p>

And then using dot notation

{{% code file="dot-notation-default-value.html" %}}

<title>{{ .Params.seo_title | default .Title }}</title>

{{% /code %}}

Which would return

{{% output file="dot-notation-default-return-value.html" %}}

<title>Sane Defaults</title>

{{% /output %}}

The following have equivalent return values but are far less terse. This demonstrates the utility of default:

Using if:

{{% code file="if-instead-of-default.html" nocopy="true" %}}

<title>{{if .Params.seo_title}}{{.Params.seo_title}}{{else}}{{.Title}}{{end}}</title>
=> Sane Defaults

{{% /code %}}

Using with:

{{% code file="with-instead-of-default.html" nocopy="true" %}}

<title>{{with .Params.seo_title}}{{.}}{{else}}{{.Title}}{{end}}</title>
=> Sane Defaults

{{% /code %}}