How Can I Display Different Content Based on a Nil Object and Property Values in Go Templates?

Allowing Nil Values in Template Conditions

When working with Go templates, you may encounter scenarios where you want to display default content if an object is nil, but show different content if a specific property is set. While it's possible to use anonymous structs, this can introduce unnecessary boilerplate.

A Versatile Solution

To solve this issue elegantly, consider the following approach:

Template Code

{{if not .}}
   // default content
{{else if eq .MetaValue "some-x"}}
   // some-x case
{{else}}
   // other case
{{end}}

Explanation

This template code evaluates the following expression in order:

1. {{if not .}}: Checks if the object is nil or otherwise empty (including false, 0, empty arrays/slices/maps, or empty strings). If it is, the default content is displayed.
2. {{else if eq .MetaValue "some-x"}}: Checks if the object has a MetaValue property set to "some-x". If it does, content specific to that property is displayed.
3. {{else}}: If neither of the previous conditions is met, any remaining content can be displayed.

By using the not operator instead of eq . nil, this approach handles all possible scenarios, including situations where the object is nil, empty, or has a value other than nil. This eliminates the need for explicit nil checks or the introduction of unnecessary anonymous structs, keeping your templates clean and concise.

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