Golang将接口{}转换为struct [英] Golang convert interface{} to struct

问题描述

我想在下面的代码中改进getCustomerFromDTO方法，我需要从接口{}创建一个结构，目前我需要将该接口编组为byte []，然后将数组解组为我的结构-必须存在更好的方法.

I want to improve the getCustomerFromDTO method in the code below, I need to create a struct from an interface{} and currently i need to marshall that interface to byte[] and then unmarshal the array to my struct - there must be a better way.

我的用例是我通过Rabbitmq发送结构，并使用常规DTO包装器发送结构，该包装具有有关它们的其他特定于域的数据.当我从Rabbit MQ接收DTO时，消息下方的一层将被封送给我的DTO，然后我需要从该DTO中获取我的结构.

My use case is that I send structs via rabbitmq and to send them I use this general DTO wrapper that has additional domain specific data about them. When I receive the DTO from rabbit mq one layer below the message is unmarshaled to my DTO and then i need to get my struct from that DTO.

type Customer struct {
    Name string `json:"name"`
}

type UniversalDTO struct {
    Data interface{} `json:"data"`
    // more fields with important meta-data about the message...
}

func main() {
    // create a customer, add it to DTO object and marshal it
    customer := Customer{Name: "Ben"}
    dtoToSend := UniversalDTO{customer}
    byteData, _ := json.Marshal(dtoToSend)

    // unmarshal it (usually after receiving bytes from somewhere)
    receivedDTO := UniversalDTO{}
    json.Unmarshal(byteData, &receivedDTO)

    //Attempt to unmarshall our customer
    receivedCustomer := getCustomerFromDTO(receivedDTO.Data)
    fmt.Println(receivedCustomer)
}

func getCustomerFromDTO(data interface{}) Customer {
    customer := Customer{}
    bodyBytes, _ := json.Marshal(data)
    json.Unmarshal(bodyBytes, &customer)
    return customer
}

推荐答案

在解组DTO之前，请将 Data 字段设置为所需的类型.

Before unmarshaling the DTO, set the Data field to the type you expect.

type Customer struct {
    Name string `json:"name"`
}

type UniversalDTO struct {
    Data interface{} `json:"data"`
    // more fields with important meta-data about the message...
}

func main() {
    // create a customer, add it to DTO object and marshal it
    customer := Customer{Name: "Ben"}
    dtoToSend := UniversalDTO{customer}
    byteData, _ := json.Marshal(dtoToSend)

    // unmarshal it (usually after receiving bytes from somewhere)
    receivedCustomer := &Customer{}
    receivedDTO := UniversalDTO{Data: receivedCustomer}
    json.Unmarshal(byteData, &receivedDTO)

    //done
    fmt.Println(receivedCustomer)
}

如果在解组前无法在DTO上初始化 Data 字段，则可以在解组后使用类型断言.将 encoding/json 打包将 interface {} 类型的值解散到 map [string] interface {} 中，因此您的代码如下所示:

If you don't have the ability to initialize the Data field on the DTO before it's unmarshaled, you can use type assertion after the unmarshaling. Package encoding/json unamrshals interface{} type values into a map[string]interface{}, so your code would look something like this:

type Customer struct {
    Name string `json:"name"`
}

type UniversalDTO struct {
    Data interface{} `json:"data"`
    // more fields with important meta-data about the message...
}

func main() {
    // create a customer, add it to DTO object and marshal it
    customer := Customer{Name: "Ben"}
    dtoToSend := UniversalDTO{customer}
    byteData, _ := json.Marshal(dtoToSend)

    // unmarshal it (usually after receiving bytes from somewhere)
    receivedDTO := UniversalDTO{}
    json.Unmarshal(byteData, &receivedDTO)

    //Attempt to unmarshall our customer
    receivedCustomer := getCustomerFromDTO(receivedDTO.Data)
    fmt.Println(receivedCustomer)
}

func getCustomerFromDTO(data interface{}) Customer {
    m := data.(map[string]interface{})
    customer := Customer{}
    if name, ok := m["name"].(string); ok {
        customer.Name = name
    }
    return customer
}

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