How to cast reflect.Value to its type?

Question

How to cast reflect.Value to its type?

type Cat struct { 
    Age int
}

cat := reflect.ValueOf(obj)
fmt.Println(cat.Type()) // Cat

fmt.Println(Cat(cat).Age) // doesn't compile
fmt.Println((cat.(Cat)).Age) // same

Thanks

Answer 1

concreteCat,_ := reflect.ValueOf(cat).Interface().(Cat)

see http://golang.org/doc/articles/laws_of_reflection.html fox example

type MyInt int
var x MyInt = 7
v := reflect.ValueOf(x)
y := v.Interface().(float64) // y will have type float64.
fmt.Println(y)

Answer 2

Ok, I found it

reflect.Value has a function Interface() that converts it to interface{}

Answer 3

This func auto-converts types as needed. It loads a config file values into a simple struct based on struct name and fields:

import (
    "fmt"
    toml "github.com/pelletier/go-toml"
    "log"
    "os"
    "reflect"
)
func LoadConfig(configFileName string, configStruct interface{}) {
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("LoadConfig.Recovered: ", r)
        }
    }()
    conf, err := toml.LoadFile(configFileName)
    if err == nil {
        v := reflect.ValueOf(configStruct)
        typeOfS := v.Elem().Type()
        sectionName := getTypeName(configStruct)
        for i := 0; i < v.Elem().NumField(); i++ {
            if v.Elem().Field(i).CanInterface() {
                kName := conf.Get(sectionName + "." + typeOfS.Field(i).Name)
                kValue := reflect.ValueOf(kName)
                if (kValue.IsValid()) {
                    v.Elem().Field(i).Set(kValue.Convert(typeOfS.Field(i).Type))
                }
            }
        }
    } else {
        fmt.Println("LoadConfig.Error: " + err.Error())
    }
}

Answer 4

Seems the only way would be to do a switch statement similar to (code below) (also, something like the commented line would've-been nice though doesn't work (:()):

 func valuesFromStruct (rawV interface{}) []interface{} { v := reflect.ValueOf(rawV) out := make([]interface{}, 0) for i := 0; i < v.NumField(); i += 1 { field := v.Field(i) fieldType := field.Type() // out = append(out, field.Interface().(reflect.PtrTo(fieldType))) switch (fieldType.Name()) { case "int64": out = append(out, field.Interface().(int64)) break`enter code here` case "float64": out = append(out, field.Interface().(float64)) break case "string": out = append(out, field.Interface().(string)) break // And all your other types (here) ... default: out = append(out, field.Interface()) break } } return out }

Cheers!