isset

将以下英文翻译为中文：

isset

https://gohugo.io/functions/isset/

Returns true if the parameter is set.

语法

isset COLLECTION INDEX
isset COLLECTION KEY

Takes either a slice, array, or channel and an index or a map and a key as input.

1

{{ if isset .Params "project_url" }} {{ index .Params "project_url" }}{{ end }}

All site-level configuration keys are stored as lower case. Therefore, a myParam key-value set in your site configuration file needs to be accessed with {{ if isset .Site.Params "myparam" }} and not with {{ if isset .Site.Params "myParam" }}. Note that you can still access the same config key with .Site.Params.myParam or .Site.Params.myparam, for example, when using with. This restriction also applies when accessing page-level front matter keys from within shortcodes.