在Golang中制作哈希数组

Question

I'm brand new to Go and having some trouble with nested data structures. Below is a array of hashes I mocked up that I need to make in Golang. I'm just confused with the whole having to declare the variable type beforehand and whatnot. Any ideas?

 var Array = [
   {name: 'Tom', dates: [20170522, 20170622], images: {profile: 'assets/tom-profile', full: 'assets/tom-full'}},
   {name: 'Pat', dates: [20170515, 20170520], images: {profile: 'assets/pat-profile', full: 'assets/pat-full'}} 
    ...,
    ... ]

Answer 1

What is called a 'hash' in Ruby is called a 'map' (translating keys to values) in Go.

However, Go is a statically typechecked language. A map can only map a certain type to another type, e.g. a map[string]int maps string values to integeger. That is not what you want here.

So what you want is a struct. Indeed, you need to define the type beforehand. So what you would do:

// declaring a separate 'Date' type that you may or may not want to encode as int. 
type Date int 
type User struct {
    Name string
    Dates []Date
    Images map[string]string
}

Now that this type is defined, you can use it in another type:

ar := []User{
  User{
    Name: "Tom",
    Dates: []Date{20170522, 20170622},
    Images: map[string]string{"profile":"assets/tom-profile", "full": "assets/tom-full"},
  },
  User{
    Name: "Pat",
    Dates: []Date{20170515, 20170520},
    Images: map[string]string{"profile":"assets/pat-profile", "full": "assets/pat-full"},
  },
}   

Note how we are defining User as a struct, but images as a map of string to image. You could also define a separate Image type:

type Image struct {
  Type string // e.g. "profile"
  Path string // e.g. "assets/tom-profile"
}

You would then not define Images as map[string]string but as []Image, that is, slice of Image structs. Which one is more appropriate depends on the use case.