有没有更好的方法来声明json变量

Question

Declaring a variable of type map[string]map[string]... is not ideal, is there a better way

    snaps := map[string]map[string]map[string]map[string]string{
    "distros": {
        "aws": {
            "eu-west-1": {
                "snap-0": "/dev/sdm",
            },
            "eu-west-2": {
                "snap-1": "/dev/sdm",
            },
        },
    },
}

fmt.Println(snaps["distros"]["aws"]["eu-west-1"])

Answer 1

The simplest way would be to use the type map[string]interface{}. Since the empty interface, interface{}, refers to any type and therefore handles the arbitrarily nested nature of JSON.

To do this you'll have to write your literal data as a string first and then parse the string into a Go map.

With that in mind here is a refactor of your example:

first: import "encoding/json", then

snapsStr := `{
    "distros": {
        "aws": {
            "eu-west-1" : {
                "snap-0": "/dev/sdm"
            },
            "eu-west-2": {
                "snap-1": "/dev/sdm"
            }
        }
    }
}`

var snaps map[string]interface{}

json.Unmarshal([]byte(snapsStr), &snaps)

And now snaps is as desired.

This is the most generic format for JSON data in Go and is one of the ways that the Go JSON library handles types for JSON. See these docs: https://golang.org/pkg/encoding/json/#Unmarshal