如何初始化嵌套结构？ [英] How to initialise nested structs in go?

问题描述

您好，我对Golang很新，请帮助我。我在结构体中定义了一个结构体。但是当我尝试初始化主结构时出现错误。

 类型DetailsFilter结构{
 Filter结构{
名称字符串
 ID int 
} 
} 
 
 var M map [string] interface {} 
 M = make（map [string] interface {}）
 M [Filter] = map [string] interface {} {Name：XYZ，ID：5} 
 var detailsFilter = DetailsFilter {Filter：M [Filter]}} 
  

我得到的错误是：无法使用（type interface {}）作为字段值中的类型struct：need type assertion。

请建议一种初始化DetailsFilter的方法。
我尝试了在Golang中初始化一个嵌套结构，但即使这不起作用。

解决方案

不幸的是，如果struct字段的类型是一个匿名结构体，在构建时，那么您可以只需通过复制匿名结构类型（再次指定它）来初始化它：

  type DetailsFilter struct {
 Filter struct {
 Name string 
 ID int 
} 
} 
 
 df：= DetailsFilter {Filter：struct {
 Name string 
 ID int 
} {名称：myname，ID：123}} 
 fmt.Println（df）
  

输出：

  {过滤器：{Name：myname ID：123}} 
  

Shorter Alternative

所以我建议不要初始化它在构建时，而是在创建零值结构之后，如下所示：

  df = DetailsFilter {} 
 df.Filter.Name =myname2
 df.Filter.ID = 321 
 fmt.Printf（％+ v \ n，df）
  

输出：

  {过滤器：{Name：myname2 ID：321}} 
  

试试 Go Playground 。

命名匿名结构类型

或者不要使用匿名结构作为字段类型，命名类型是这样的：

 类型Filter结构{
名称字符串
 ID int 
 
 
类型DetailsFilter结构{
 Filter Filter 
} 
  

然后您可以简单地初始化它：

  df：= DetailsFilter {Filter：Filter {名称：myname，ID：123}} 
 fmt.Printf（％+ v \ n，df）
  

输出（在 Go Playground 上试用）：

  {过滤器：{Name：myname ID：123}} 
  

Hi I am very new to Golang, please help me. I have defined a struct inside a struct. But I get an error when I try to initialise the main struct.

type DetailsFilter struct {
  Filter struct {
    Name    string        
    ID      int                           
  } 
}

var M map[string]interface{}
M = make(map[string]interface{})
M["Filter"] = map[string]interface{}{"Name": "XYZ", "ID": 5}
var detailsFilter = DetailsFilter{Filter: M["Filter"]}}

The error I get is : can not use (type interface {}) as type struct in field value : need type assertion.

Please suggest a way to initialise DetailsFilter. I tried doing the method described in Initialize a nested struct in Golang, but even this is not working.

解决方案

Unfortunately if the type of a struct field is an anonymous struct, at construction time you can only initialize it by "duplicating" the anonymous struct type (specifying it again):

type DetailsFilter struct {
    Filter struct {
        Name string
        ID   int
    }
}

df := DetailsFilter{Filter: struct {
    Name string
    ID   int
}{Name: "myname", ID: 123}}
fmt.Println(df)

Output:

{Filter:{Name:myname ID:123}}

Shorter Alternative

So instead I recommend not to initialize it at construction, but rather after the zero-valued struct has been created, like this:

df = DetailsFilter{}
df.Filter.Name = "myname2"
df.Filter.ID = 321
fmt.Printf("%+v\n", df)

Output:

{Filter:{Name:myname2 ID:321}}

Try it on the Go Playground.

Naming the anonymous struct type

Or don't use anonymous struct as field type at all, name the type like this:

type Filter struct {
    Name string
    ID   int
}

type DetailsFilter struct {
    Filter Filter
}

And then you can simply initialize it like this:

df := DetailsFilter{Filter: Filter{Name: "myname", ID: 123}}
fmt.Printf("%+v\n", df)

Output (try it on the Go Playground):

{Filter:{Name:myname ID:123}}

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