从结构迭代中排除空字段

Question

I have a struct that will get its value from user input. Now I want to extract only field names that have associated values. Fields with a nil value should not be returned. How can I do that?

Here’s my code:

package main


import "fmt"
import "reflect"

type Users struct {
    Name string
    Password string
}


func main(){
    u := Users{"Robert", ""}

    val := reflect.ValueOf(u)


    for i := 0; i < val.NumField(); i++ {

        fmt.Println(val.Type().Field(i).Name)

    }


} 

Current Result:

Name
Password

Expected result:

Name

Answer 1

You need to write a function to check for empty:

func empty(v reflect.Value) bool {
    switch v.Kind() {
    case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
        return v.Int() == 0
    case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
        return v.Uint() == 0
    case reflect.String:
        return v.String() == ""
    case reflect.Ptr, reflect.Slice, reflect.Map, reflect.Interface, reflect.Chan:
        return v.IsNil()
    case reflect.Bool:
        return !v.Bool()
    }
    return false
}

playground example.