github.com/jbramsden/hugo@v0.47.1/docs/content/en/functions/isset.md (about)

     1  ---
     2  title: isset
     3  linktitle: isset
     4  description: Returns true if the parameter is set.
     5  godocref:
     6  date: 2017-02-01
     7  publishdate: 2017-02-01
     8  lastmod: 2017-02-01
     9  categories: [functions]
    10  menu:
    11    docs:
    12      parent: "functions"
    13  keywords: []
    14  signature: ["isset COLLECTION INDEX", "isset COLLECTION KEY"]
    15  workson: []
    16  hugoversion:
    17  relatedfuncs: []
    18  deprecated: false
    19  aliases: []
    20  ---
    21  
    22  Takes either a slice, array, or channel and an index or a map and a key as input.
    23  
    24  ```
    25  {{ if isset .Params "project_url" }} {{ index .Params "project_url" }}{{ end }}
    26  ```
    27  
    28  {{% warning %}}
    29  All site-level configuration keys are stored as lower case. Therefore, a `myParam` key-value set in your [site configuration file](/getting-started/configuration/) 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`](/functions/with).
    30  {{% /warning %}}
    31