Convert []interface to []string in Golang

I'm using the github.com/fatih/structs package to convert values of all fields of a struct into []interface{} with the toValues() function. See here. This works fine, but eventually I want to write the values to a csv file by using the csv package. The csv.Write() function requires []string as input.

So in short: how can I easily convert the output of toValues() into an array of strings?

You can't simply convert []interface{} to []string even if all the values are of concrete type string, because those 2 types have different memory layout / representation. For details see https://stackoverflow.com/questions/12990338/cannot-convert-string-to-interface.

You have to define how you want values of different types to be represented by string values.

The easiest and sensible way would be to iterate over the values, and use fmt.Sprint() to obtain a string representation of each, e.g.:

t := []interface{}{
	"zero",
	1, 2.0, 3.14,
	[]int{4, 5},
	struct{ X, Y int }{6, 7},
}
fmt.Println(t)

s := make([]string, len(t))
for i, v := range t {
	s[i] = fmt.Sprint(v)
}
fmt.Println(s)
fmt.Printf("%q\n", s)

Output (try it on the Go Playground):

[zero 1 2 3.14 [4 5] {6 7}]
[zero 1 2 3.14 [4 5] {6 7}]
["zero" "1" "2" "3.14" "[4 5]" "{6 7}"]

you can, just do:

    func text(msg ...interface{}) string {
        return fmt.Sprintf("%+v", msg...)
    }

Use fmt.Sprintf to convert an interface value to a string. In fact, this technique can be used to get a string representation of any data structure.

Here is the code sample,

var Foo interface{} = "Value"

str := fmt.Sprintf("%v", Foo)