How do I assign variables within a conditional

Question

Given a YAML file and go templates, I can assign a variable with:

{{ $foo := "bar" }}

And I can use a conditional like:

{{ if eq $foo "bar" }} jim {{ else }} bob {{ end }}

How do I combine the two to assign the result of a condition to a variable?

I've tried:

{{ $foo := "bar" }}

{{ if eq $foo "bar" }}
{{ $foo = "jim" }} 
{{ else }}
{{ $foo = "bob" }}
{{ end }}

But foo remains bar

This kind of logic is generally best kept out of templates, either by doing the logic and passing the correct value in with the template data, or by adding a custom template function to do the logic. — Adrian, Aug 22 '18 at 15:06

icza · Accepted Answer · 2018-08-22T19:43:36.603

This is not possible with Go 1.10 and earlier versions, template variables (identifiers) cannot be modified (there are "workarounds", see following link). They can be re-declared / shadowed in a(n inner) block, but once you are out of the inner block, the changes will not be visible. For details and workarounds, see In a Go template range loop, are variables declared outside the loop reset on each iteration?

Note that however Go 1.11 is about to be released which will support this.

This will be a valid and working template code starting with Go 1.11:

{{ $v := "init" }}
{{ if true }}
  {{ $v = "changed" }}
{{ end }}
v: {{ $v }} {{/* "changed" */}}

How do I assign variables within a conditional

1 Answers1

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