在Go中,http表单数据(例如来自POST或PUT请求)可以作为表单映射[string] []字符串的映射来访问.我很难以一种普遍的方式将其转换为结构体.
@H_502_1@例如,我想加载一个地图,如：
m := map[string][]string {
"Age": []string{"20"},"Name": []string{"John Smith"},}
@H_502_1@进入如下模型：
type Person struct {
Age int
Name string
}
@H_502_1@所以我正在尝试使用签名LoadModel(obj interface {},m map [string] [] string)[]错误编写一个函数,它将表单数据加载到我可以键入的接口{}中.人.使用反射,以便我可以在任何字段上使用它,而不仅仅是一个Person,这样我就可以根据需要将字符串从http数据转换为int,boolean等.
@H_502_1@使用这个问题的答案in golang,using reflect,how do you set the value of a struct field?我可以使用反射来设定一个人的价值,例如：
p := Person{25,"John"}
reflect.ValueOf(&p).Elem().Field(1).SetString("Dave")
@H_502_1@但是我必须为我拥有的每种类型的结构复制加载函数.当我尝试接口{}时它不起作用.
pi := (interface{})(p)
reflect.ValueOf(&pi).Elem().Field(1).SetString("Dave")
// panic: reflect: call of reflect.Value.Field on interface Value
@H_502_1@在一般情况下我该怎么做？或者甚至更好,是否有更惯用的Go方式来完成我想要做的事情？
为了好玩,我试了一下.请注意,我作弊了一点(见评论),但你应该得到照片.使用反射与静态类型分配(如nemo的答案)通常需要花费成本,所以一定要在你的决定中权衡(尽管我没有对它进行基准测试).
@H_502_1@此外,明显的免责声明,我没有测试所有边缘情况等,不要只是复制粘贴在生产代码:)
@H_502_1@所以这里是：
原文链接：https://www.f2er.com/go/186904.htmlpackage main
import (
"fmt"
"reflect"
"strconv"
)
type Person struct {
Age int
Name string
Salary float64
}
// I cheated a little bit,made the map's value a string instead of a slice.
// Could've used just the index 0 instead,or fill an array of structs (obj).
// Either way,this shows the reflection steps.
//
// Note: no error returned from this example,I just log to stdout. Could definitely
// return an array of errors,and should catch a panic since this is possible
// with the reflect package.
func LoadModel(obj interface{},m map[string]string) {
defer func() {
if e := recover(); e != nil {
fmt.Printf("Panic! %v\n",e)
}
}()
val := reflect.ValueOf(obj)
if val.Kind() == reflect.Ptr {
val = val.Elem()
}
// Loop over map,try to match the key to a field
for k,v := range m {
if f := val.FieldByName(k); f.IsValid() {
// Is it assignable?
if f.CanSet() {
// Assign the map's value to this field,converting to the right data type.
switch f.Type().Kind() {
// Only a few kinds,just to show the basic idea...
case reflect.Int:
if i,e := strconv.ParseInt(v,0); e == nil {
f.SetInt(i)
} else {
fmt.Printf("Could not set int value of %s: %s\n",k,e)
}
case reflect.Float64:
if fl,e := strconv.ParseFloat(v,0); e == nil {
f.SetFloat(fl)
} else {
fmt.Printf("Could not set float64 value of %s: %s\n",e)
}
case reflect.String:
f.SetString(v)
default:
fmt.Printf("Unsupported format %v for field %s\n",f.Type().Kind(),k)
}
} else {
fmt.Printf("Key '%s' cannot be set\n",k)
}
} else {
// Key does not map to a field in obj
fmt.Printf("Key '%s' does not have a corresponding field in obj %+v\n",obj)
}
}
}
func main() {
m := map[string]string{
"Age": "36","Name": "Johnny","Salary": "1400.33","Ignored": "True",}
p := new(Person)
LoadModel(p,m)
fmt.Printf("After LoadModel: Person=%+v\n",p)
}
