利用reflect设置struct的字段

极为重要的两篇文章

1. http://speakmy.name/2014/09/14/modifying-interfaced-go-struct/

Combining it all together, this is the final function:

func Destroy(subj interface{}) {stype := reflect.ValueOf(subj).Elem()field := stype.FieldByName("Status")if field.IsValid() {field.SetString("Destroyed")}}

func TestDestroy(t *testing.T) {// Initialize datajaeger := Jaeger{Name: "Cherno Alpha", Country: "RU", Status: "Active"}kaiju := Kaiju{Alias: "Scissure", Origin: "Sydney", Status: "Unknown"}shatterdome := Shatterdome{Location: "Lima"}// Destroy everythingDestroy(&jaeger)Destroy(&kaiju)Destroy(&shatterdome)// Check the resultif jaeger.Status != "Destroy" {t.Error("jaeger was not destroyed")}if kaiju.Status != "Destroy" {t.Error("kaiju was not destroyed")}}

2.

参考golang反射三大规则

reflect.Value区分CanSet和Can not Set的, 所以, 必须要返回成Can set的reflect.Value
如:

s := reflect.ValueOf(&t).Elem()

然后就可以happy的设值了, 可是不能随便设值的, 一个通用的方法就是使用Set(v Value)方法, 所以之前必须将值转成reflect.Value类型, 下面的这段代码就是转成Value类型

sliceValue := reflect.ValueOf([]int{1, 2, 3}) // 这里将slice转成reflect.Value类型

完整参考:

type T struct {    Age int    Name string    Children []int}t := T{12, "someone-life", nil}s := reflect.ValueOf(&t).Elem()s.Field(0).SetInt(123) // 内置常用类型的设值方法sliceValue := reflect.ValueOf([]int{1, 2, 3}) // 这里将slice转成reflect.Value类型s.FieldByName("Children").Set(sliceValue)

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How to use Reflect to set a struct field

http://samwize.com/2015/03/20/how-to-use-reflect-to-set-a-struct-field/

In short, if you want to set a struct foo object when you know the field name to set, this is the code:

func setFoo(foo *Foo, field string, value string) {
    v := reflect.ValueOf(foo).Elem().FieldByName(field)
    if v.IsValid() {
        v.SetString(value)
    }
}

If you want to print all the fields of foo, this is the code:

s := reflect.ValueOf(foo).Elem()
typeOfT := s.Type()
for i := 0; i < s.NumField(); i++ {
    f := s.Field(i)
    fmt.Printf("%d: %s %s = %v\n", i,
        typeOfT.Field(i).Name, f.Type(), f.Interface())
}