如何在条件中分配变量

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

Answer 1

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" */}}