描述

想做一个类似于orm的数据组件，遇到这个问题，把一个[]map[string]interface{}的response转换成对应类型的结构体数组里面

思路

看了orm的源码，以及网上的一些文章，然后用反射完成了单个结构体赋值，也就是orm中的err := o.Read(&user)，做数组时参考了orm中的func (o *rawSet) QueryRows(containers ...interface{}) (int64, error)

相关代码

package test

import (
    "errors"
    "fmt"
    "reflect"
    "strings"
)

func MapToStruct() {
    mList := []map[string]interface{}{
        {"Id": 213, "Name": "zhaoliu", "Sex": "男"},
        {"Id": 56, "Name": "zhangsan", "Sex": "男"},
        {"Id": 7, "Name": "lisi", "Sex": "女"},
        {"Id": 978, "Name": "wangwu", "Sex": "男"},
    }

    type User struct {
        Id   int
        Name string
        Sex  string
    }
    users := []*User{}

    mapToStruct(mList, &users)
    fmt.Printf("users: %+v\n", users)
}

func mapToStruct(mList []map[string]interface{}, model interface{}) (err error) {
    val := reflect.Indirect(reflect.ValueOf(model))
    typ := val.Type()

    fmt.Printf("val: %v\n", val)
    fmt.Printf("typ: %v\n", typ)

    for _, r := range mList {
        mVal := reflect.Indirect(reflect.New(typ.Elem().Elem())).Addr()
        //fmt.Printf("mVal: %+v\n", mVal)
        for key, val := range r {
            err = setField(mVal.Interface(), key, val)
            if err != nil {
                return err
            }
        }
        //fmt.Printf("mVal: %+v\n", mVal)
        val = reflect.Append(val, mVal)
    }
    fmt.Printf("val: %+v\n", val.Interface())
    //model = val.Interface()
    return err
}

//用map的值替换结构的值
func setField(obj interface{}, name string, value interface{}) error {
    // 将首字母转换为大写
    sl := strings.Split(name, "")
    sl[0] = strings.ToUpper(sl[0])
    name = strings.Join(sl, "")

    structValue := reflect.ValueOf(obj).Elem() //结构体属性值
    //fmt.Printf("structValue: %+v\n", structValue)
    structFieldValue := structValue.FieldByName(name) //结构体单个属性值
    //fmt.Printf("structFieldValue: %+v\n", structFieldValue)
    if !structFieldValue.IsValid() {
        return fmt.Errorf("No such field: %s in obj", name)
    }

    if !structFieldValue.CanSet() {
        return fmt.Errorf("Cannot set %s field value", name)
    }

    structFieldType := structFieldValue.Type() //结构体的类型
    val := reflect.ValueOf(value)              //map值的反射值

    if structFieldType != val.Type() {
        return errors.New("type is err")
    }

    structFieldValue.Set(val)
    return nil
}