CODEWITHSUNDEEP
go
user2315104
user2315104

Reputation: 2728

How can i declare list of maps in golang

i am not getting how should i format the struct in golang so that i can get the list of maps (key/value pairs) in JSON format ? So far i tried with this 

package main

import (
"encoding/json"
"fmt"
)

func main() {
map1 := map[string]interface{}{"dn": "abc", "status": "live", "version": 2, "xyz": 3}
map2, _ := json.Marshal(map1)
fmt.Println(string(map2))
}

here it is just printing key/value pairs...

{"dn":"abc","status":"live","version":2,"xyz":3}

but i need output something like this :

[{"dn":"abc","status":"live"},{"version":2,"xyz":3}]

Upvotes: 17

Views: 27900

Answers (2)

Kevin Wang
Kevin Wang

Reputation: 682

I had the same question, and answered myself (No struct usage for my case)

package main

import "fmt"

func main() {
    mapSlice := []map[string]interface{}{}

    map1 := map[string]interface{}{"foo": "bar"}
    mapSlice = append(mapSlice, map1)

    fmt.Println(mapSlice[0]["foo"]) // prints "bar"
}

https://go.dev/play/p/BOCVAOngul2

Upvotes: 3

stevenferrer
stevenferrer

Reputation: 2612

As suggested by @Volker, you should use slice of maps:

package main

import (
    "fmt"
    "encoding/json"
)

// M is an alias for map[string]interface{}
type M map[string]interface{}

func main() {
    var myMapSlice []M

    m1 := M{"dn": "abc", "status": "live"}

    m2 := M{"version": 2, "xyz": 3}

    myMapSlice = append(myMapSlice, m1, m2)

    // or you could use `json.Marshal(myMapSlice)` if you want
    myJson, _ := json.MarshalIndent(myMapSlice, "", "    ")
    fmt.Println(string(myJson))
}

Outputs:

[
    {
        "dn": "abc",
        "status": "live"
    },
    {
        "version": 2,
        "xyz": 3
    }
]

From the code, I've used an alias for map[string]interface{} to make it more convenient to initialize a map of interface.

Link to code: https://play.golang.org/p/gu3xafnAyG

Upvotes: 34

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