用另一个结构体赋值struct [英] Assign struct with another struct

问题描述

  type RegistrationRequest struct {
 Email * string 
 Email2 *字符串
用户名*字符串
密码*字符串
名称字符串
} 
  

其中电子邮件2 是再次输入的电子邮件值，以验证用户输入的内容是否正确。

我也有一个用户结构：

 类型用户结构{
电子邮件*字符串
用户名*字符串
密码*字符串
名称字符串
} 
  

当然，没有必要存储超过注册的 Email2 。

所以我有两个变量： req 和 u - 每个结构体一个。是否可以将 req 结构分配给 u 结构，这样所有的公共字段将存在于 u struct？

解决方案

使用简单的赋值，因为即使 User 的字段是 RegistrationRequest ，它们完全是两种不同的类型，而赋值规则不适用。

您可以编写一个使用反射的函数（ reflect 包），并将所有字段从 req 复制到 u ，但这只是丑陋的（而且效率低下）。

最好的办法是重构你的类型， code> RegistrationRequest 可以 embed User 。

如果您的类型值 RegistrationRequest ，这意味着您已经具有 User 的值：

类型User struct {
电子邮件*字符串
用户名*字符串
密码*字符串
名称字符串
} 
 
 type RegistrationRequest struct {
 User //嵌入用户类型
 Email2 * string 
} 
 
 func main（）{
 req：= RegistrationRequest {} 
s：=[e-mail]
 req.Email =& s 
 
 s2：=testuser
 req.Username =& s2 
 $ b $：$ User $ {
u} / code> 

输出：（在

  testuser [e-mail] 
  Go Playground ） c $ c> 

另外请注意，由于您的structs co ntain指针，当复制 struct 时，指针值将被复制，而不是指向值。我不确定为什么你需要指针，最好只声明所有的字段是非指针。



另外请注意，嵌入并不是真正的要求，它只是让你的类型和使用更加流畅。 用户也可以是 RequisitionRequest 的普通字段，例如：

  type RegistrationRequest struct {
 Usr User //这只是一个普通的字段，不包含
 Email2 * string 
} 
  




I have a RegistrationRequest struct:

type RegistrationRequest struct {
    Email    *string
    Email2   *string        
    Username *string
    Password *string
    Name     string
}

Where Email2 is the email value entered again to verify that what the user entered is correct.

I also have a User struct:

type User struct {
    Email    *string
    Username *string
    Password *string
    Name     string           
}

Of course, there is no need to store Email2 beyond registration.

So I have two variables: req and u - one for each struct. Is it possible to assign the req struct into to the u struct so that all the common fields will exist in the u struct?

解决方案

Using simple assignment you can't because even though the fields of User are a subset of RegistrationRequest, they are completely 2 different types, and Assignability rules don't apply.

You could write a function which uses reflection (reflect package), and would copy all the fields from req to u, but that is just ugly (and inefficient).

Best would be to refactor your types, and RegistrationRequest could embed User.

Doing so if you have a value of type RegistrationRequest that means you already also have a value of User:

type User struct {
    Email    *string
    Username *string
    Password *string
    Name     string
}

type RegistrationRequest struct {
    User  // Embedding User type
    Email2 *string
}

func main() {
    req := RegistrationRequest{}
    s := "[e-mail]"
    req.Email = &s

    s2 := "testuser"
    req.Username = &s2

    u := User{}
    u = req.User
    fmt.Println(*u.Username, *u.Email)
}

Output: (try it on the Go Playground)

testuser [e-mail]

Also please note that since your structs contain pointers, when copying a struct, pointer values will be copied and not pointed values. I'm not sure why you need pointers here, would be best to just declare all fields to be non-pointers.

Also note that embedding is not really a requirement, it just makes your types and their usage more smooth. User could just as well be an "ordinary" field of RequistrationRequest, e.g.:

type RegistrationRequest struct {
    Usr User // This is just an ordinary field, not embedding
    Email2 *string
}

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