default
Syntax
default DEFAULT INPUT
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 the data 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:
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:
---
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:
variable-as-default-value.html
{{$old := .Params.oldparam }}
<p>{{ .Params.newparam | default $old }}</p>
Which would return:
<p>The default function helps make your templating DRYer.</p>
And then using dot notation
dot-notation-default-value.html
<title>{{ .Params.seo_title | default .Title }}</title>
Which would return
dot-notation-default-return-value.html
<title>Sane Defaults</title>
The following have equivalent return values but are far less terse. This demonstrates the utility of default:
Using if:
if-instead-of-default.html
<title>{{if .Params.seo_title}}{{.Params.seo_title}}{{else}}{{.Title}}{{end}}</title>
=> Sane Defaults
Using with:
with-instead-of-default.html
<title>{{with .Params.seo_title}}{{.}}{{else}}{{.Title}}{{end}}</title>
=> Sane Defaults