如何在GO中的嵌套json结构中初始化值？ [重复]

Question

This question already has an answer here:

• Initialize nested struct definition in Golang 3 answers

I have this struct right now

type ServiceStruct struct {
      Name     string `json:"name"`
      DataStruct struct {
          ID    string `json:"id"`
          Size  string `json:"size"`
     }
}

But im not sure how to assign values to the elements inside this struct. Specially the DataStruct inside the ServiceStruct

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Answer 1

You can either use an anonymous struct literal (which requires copy-pasting the type of DataStruct) or assign values to individual fields using =.

package main

import (
    "fmt"
)

type ServiceStruct struct {
    Name       string `json:"name"`
    DataStruct struct {
        ID   string `json:"id"`
        Size string `json:"size"`
    }
}

func main() {
    s1 := ServiceStruct{
        Name: "foo",
        DataStruct: struct {
            ID   string `json:"id"`
            Size string `json:"size"`
        }{
            ID:   "bar",
            Size: "100",
        },
    }

    s2 := ServiceStruct{
        Name: "foo",
    }
    s2.DataStruct.ID = "bar"
    s2.DataStruct.Size = "100"

    fmt.Println(s1)
    fmt.Println(s2)

    // Output:
    // {foo {bar 100}}
    // {foo {bar 100}}
}

Alternatively, consider giving the type of DataStruct a name so you can refer to it in the struct literal instead of copy-pasting (which is not recommended).