For logging purposes I want to be able to quickly write a slice of any type, whether it be ints, strings, or custom structs, to a file in Go. For instance, in C#, I can do the following in 1 line:
File.WriteAllLines(filePath, myCustomTypeList.Select(x => x.ToString());
How would I go about doing this in Go? The structs implement the Stringer
interface.
Edit: I in particular would like the output to be printed to a file and one line per item in the slice
Use the fmt package format values as strings and print to a file:
func printLines(filePath string, values []interface{}) error {
f, err := os.Create(filePath)
if err != nil {
return err
}
defer f.Close()
for _, value := range values {
fmt.Fprintln(f, value) // print values to f, one per line
}
return nil
}
fmt.Fprintln
will call Stringer()
on your struct type. It will also print int
values and string
values.
Use the reflect package to write any slice type:
func printLines(filePath string, values interface{}) error {
f, err := os.Create(filePath)
if err != nil {
return err
}
defer f.Close()
rv := reflect.ValueOf(values)
if rv.Kind() != reflect.Slice {
return errors.New("Not a slice")
}
for i := 0; i < rv.Len(); i++ {
fmt.Fprintln(f, rv.Index(i).Interface())
}
return nil
}
If you have variable values
of type myCustomList
, then you can call it like this: err := printLines(filePath, values)