I have a custom function using Go templates as follows:

"listOperate": func(lst []string, fn func(string) string) (result []string) {
    result = make([]string, len(lst))
    for i, item := range lst {
        result[i] = fn(item)
    }
    return result
},

I have another function which operates on a string:

"toCamel": func(str string) (result string) {
        return strcase.ToCamel(str)
    }

How can I call the first function, using the second as a parameter?

Copilot gives me the following

{{ listOperate . toCamel}}

which makes sense but fails to parse with the error

at <toCamel>: wrong number of args for toCamel: want 1 got 0" (template.ExecError)

which suggests it is trying to execute the function instead of passing it. Google gives me plenty of information on custom functions but nothing answers this problem.

I have a custom function using Go templates as follows:

"listOperate": func(lst []string, fn func(string) string) (result []string) {
    result = make([]string, len(lst))
    for i, item := range lst {
        result[i] = fn(item)
    }
    return result
},

I have another function which operates on a string:

"toCamel": func(str string) (result string) {
        return strcase.ToCamel(str)
    }

How can I call the first function, using the second as a parameter?

Copilot gives me the following

{{ listOperate . toCamel}}

which makes sense but fails to parse with the error

at <toCamel>: wrong number of args for toCamel: want 1 got 0" (template.ExecError)

which suggests it is trying to execute the function instead of passing it. Google gives me plenty of information on custom functions but nothing answers this problem.

• go
• templates

1 Answer 1

There is not a way to name a function without calling the function. The code {{ listOperate . toCamel}} calls toCamel with no arguments.

Write a template function that returns the function:

"toCamelFunc": func() any {
    return func(str string) (result string) {
        return strcase.ToCamel(str)
    }
}

Use it like this: {{ listOperate . toCamelFunc}}