function with receiver that iterates through some field of struct in go - go

Question

i'm a Golang newbie trying to build a simple CLI. I'm converting an API call payload into an struct and want to format some information from this struct into a nice printable string. One of the informations i want to print is from an array of structs, like in this example:
type Pokemon struct {
Abilities []struct {
Ability struct {
Name string `json:"name"`
URL string `json:"url"`
} `json:"ability"`
IsHidden bool `json:"is_hidden"`
Slot int `json:"slot"`
} `json:"abilities"`
Height int `json:"height"`
ID int `json:"id"`
Name string `json:"name"`
Types []struct {
Slot int `json:"slot"`
Type struct {
Name string `json:"name"`
URL string `json:"url"`
} `json:"type"`
} `json:"types"`
Weight int `json:"weight"`
}
}
I'm trying to write a generic receptor function that iterates over some fields that are struct arrays and join its fields in a string. I can do a function that iterate specifically over some field like this:
func (p Pokemon) stringifyPokemonAbilities() string {
var listOfAbilities []string
for _, ability := range p.Abilities {
listOfAbilities = append(listOfAbilities, ability.Ability.Name)
}
return strings.Join(listOfAbilities[:], " / ")
}
Returning e.g. synchronize / inner-focus
Working like this, i'll have to write almost the same function to the Type field. My question is, how to make this function more generic, accepting a field and iterating on it. Any thoughts?

Answer 1

You could do that using relfect. There is a well written tutorial, which you could have a look at.
According to the struct you give, I have written a demo. The main idea is
find the struct filed by name, then iterator the slice, find the name in the struct.
You could get the answer using p.stringifyPokemon("Types") or p.stringifyPokemon("Abilities") now.
func (p Pokemon) stringifyPokemon(field string) string {
value := reflect.ValueOf(p)
struct1 := value.FieldByName(field)
if !struct1.IsValid() {
return ""
}
if struct1.Type().Kind() != reflect.Slice {
return ""
}
ans := make([]string, 0)
for i := 0; i < struct1.Len(); i++ {
slice1 := struct1.Index(i)
if slice1.Type().Kind() != reflect.Struct {
continue
}
for j := 0; j < slice1.NumField(); j++ {
struct2 := slice1.Field(j)
if struct2.Type().Kind() != reflect.Struct {
continue
}
name := struct2.FieldByName("Name")
if name.Kind() != reflect.String {
continue
}
ans = append(ans, name.String())
}
}
return strings.Join(ans[:], " / ")
}