How to initialize a nested struct

Question

I cannot figure out how to initialize a nested struct  Find an example here  http   play golang org p NL6VXdHrjh package main  type Configuration struct       Val   string     Proxy struct           Address string         Port    string          func main          c     amp Configuration          Val   quot test quot           Proxy                Address   quot addr quot               Port      quot 80 quot

User · Answer

You need to redefine the unnamed struct during &Configuration{}

package main

import "fmt"

type Configuration struct {
    Val   string
    Proxy struct {
        Address string
        Port    string
    }
}

func main() {

    c := &Configuration{
        Val: "test",
        Proxy: struct {
            Address string
            Port    string
        }{
            Address: "127.0.0.1",
            Port:    "8080",
        },
    }
    fmt.Println(c)
}

https://play.golang.org/p/Fv5QYylFGAY

User · Answer

You have this option also   type Configuration struct           Val string         Proxy    type Proxy struct           Address string         Port    string    func main             c     amp Configuration  test   Proxy  addr    port            fmt Println c

User · Answer

package main  type    Proxy struct           Address string         Port    string        type Configuration struct       Proxy     Val   string     func main          c     amp Configuration          Val   quot test quot           Proxy  Proxy               Address   quot addr quot               Port      quot 80 quot

User · Answer

Well  any specific reason to not make Proxy its own struct   Anyway you have 2 options   The proper way  simply move proxy to its own struct  for example   type Configuration struct       Val string     Proxy Proxy    type Proxy struct       Address string     Port    string    func main          c     amp Configuration          Val   test           Proxy  Proxy              Address   addr               Port      port                        fmt Println c      fmt Println c Proxy Address      The less proper and ugly way but still works   c     amp Configuration      Val   test       Proxy  struct           Address string         Port    string                Address   addr           Port      80

User · Answer

If you don t want to go with separate struct definition for nested struct and you don t like second method suggested by  OneOfOne you can use this third method   package main import  fmt  type Configuration struct       Val   string     Proxy struct           Address string         Port    string          func main         c     amp Configuration          Val   test              c Proxy Address    127 0 0 1      c Proxy Port    8080      You can check it here  https   play golang org p WoSYCxzCF2

User · Answer

Define your Proxy struct separately  outside of Configuration  like this   type Proxy struct       Address string     Port    string    type Configuration struct       Val string     P   Proxy    c     amp Configuration      Val   test       P  Proxy          Address   addr           Port      80              See http   play golang org p 7PELCVsQIc

User · Answer

You can define a struct and create its object in another struct like i have done below   package main  import  fmt   type Address struct       streetNumber int     streetName   string     zipCode      int    type Person struct       name    string     age     int     address Address    func main         var p Person     p name    Vipin      p age   30     p address   Address          streetName     Krishna Pura           streetNumber  14          zipCode       475110            fmt Println  Name     p name      fmt Println  Age     p age      fmt Println  StreetName     p address streetName      fmt Println  StreeNumber     p address streetNumber      Hope it helped you

User · Answer

One gotcha arises when you want to instantiate a public type defined in an external package and that type embeds other types that are private   Example   package animals  type otherProps    Name string   Width int    type Duck    Weight int   otherProps     How do you instantiate a Duck in your own program  Here s the best I could come up with   package main  import  github com someone animals   func main      var duck animals Duck      Can t instantiate a duck with something Duck Weight  2  Name   Henry   because  Name  is part of the private type  otherProps    duck Weight   2   duck Width   30   duck Name    Henry

User · Answer

You also could allocate using new and initialize all fields by hand  package main  type Configuration struct       Val   string     Proxy struct           Address string         Port    string          func main         c    new Configuration      c Val    test      c Proxy Address    addr      c Proxy Port    80      See in playground  https   play golang org p sFH -HawO M

[go] How to initialize a nested struct?

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