英文:
Go - Idiomatic way to map one struct to another
问题
我正在使用一个第三方的Go语言库来查询LDAP用户数据库。该库返回一个SearchResult切片，其中包含我需要映射到自己的User结构体的ResultUser。这两个结构体具有不同的字段名，而且我只需要ResultUser中的特定字段。在Go语言中，是否有更符合惯用方式的方法将一个结构体转换为另一个结构体呢？
我在下面创建了一个演示示例（链接也在Go Playground上）。非常感谢您对这个Go语言新手能给出的任何建议！
package mainimport "fmt"type (User struct {id int32firstName string}ResultUser struct {uid int32fname string}SearchResults []ResultUser)func main() {results := getSearchResults()users := mapResultsToUsers(results) // <-- 这是问题所在fmt.Println("User struct:", users[0].id, users[0].firstName)fmt.Println("User struct:", users[1].id, users[1].firstName)}// 模拟使用库进行数据查询func getSearchResults() (results SearchResults) {return append(results, ResultUser{1, "John"}, ResultUser{2, "Jane"})}// 看起来这样做有点不太对劲// 是否有更符合惯用方式的方法呢？func mapResultsToUsers(results SearchResults) (users []User) {for _, result := range results {users = append(users, User{result.uid, result.fname})}return users}
我见过结构体字段标签，但不确定是否有更好的方法。
英文:
I'm using a third party Go lang library to query a LDAP database of users. The library returns a SearchResult slice of ResultUser that I need to map to my own User struct. The two structs have different field names and I only need specific fields from the ResultUser. Is there a more idiomatic way in Go to transform one struct to another.
I've created a demo below (link also on Go Playground). Thanks in advance for any advice you can give to this Go newbie!
package mainimport "fmt"type (User struct {id int32firstName string}ResultUser struct {uid int32fname string}SearchResults []ResultUser)func main() {results := getSearchResults()users := mapResultsToUsers(results) // <-- This is the problemfmt.Println("User struct:", users[0].id, users[0].firstName)fmt.Println("User struct:", users[1].id, users[1].firstName)}// Simulates a query to a data with a libraryfunc getSearchResults() (results SearchResults) {return append(results, ResultUser{1, "John"}, ResultUser{2, "Jane"})}// Seems like a code smell to have to do this// Is there a more idiomatic way to do this?func mapResultsToUsers(results SearchResults) (users []User) {for _, result := range results {users = append(users, User{result.uid, result.fname})}return users}
I've seen struct field tags but not sure if there is a better way.
答案1
得分: 1
我认为你已经得到了相当不错的解决方案，尽管我会将映射移到一个专用函数中，类似于：
func fromResultUser(r *ResultUser) *User {return &User{id: r.uid,firstName: r.fname,}}
然后mapResultsToUsers变成：
func mapResultsToUsers(results SearchResults) (users []*User) {for _, result := range results {users = append(users, fromResultUser(result))}return users}
我见过结构体字段标签，但不确定是否有更好的方法。
你可以组合一些东西，以便可以像这样注释你的User结构体：
User struct {id int32 `mappedFrom:"uid"`firstName string `mappedFrom:"fname"`}
但是，实现这种方法所需的方法比这里介绍的fromResultUser要复杂得多，并且需要熟悉reflect包。我会认为，正如我的一位同事喜欢说的那样，"得不偿失"。
英文:
I think that what you've got is pretty much the best solution, although I would move the mapping into a dedicated function, some like:
func fromResultUser(r *ResultUser) *User {return &User{id: r.uid,firstName: r.fname,}}
Then mapResultsToUsers becomes:
func mapResultsToUsers(results SearchResults) (users []*User) {for _, result := range results {users = append(users, fromResultUser(result))}return users}
> I've seen struct field tags but not sure if there is a better way.
You could put together something so that you could annotate your User struct like:
User struct {id int32 `mappedFrom:"uid"`firstName string `mappedFrom:"fname"`}
But the method required to implement that would be substantially more complex than the fromResultUser presented here, and would involve becoming familiar with the reflect package. I would argue that, as a colleague of mine is fond of saying, "the juice isn't worth the squeeze".
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