How to create a nested dictionary to post data?

{
    "data": {
        "payload": {
            "from": {
                "phone_number": "+XXXXXXXXXX"
            },

            "to": {
                "phone_number": "+XXXXXXXXXX",
			},
        }
    }
}

I'm trying to create a nested dictionary for the post body. I've tried using struct but it didn't work as I expected and while using the map[string]interface{}{} I'm getting an error.

1. Struct Route:

type Payload struct {
	From struct {
		PhoneNumber string `json:"phone_number"`
	}
	To  struct {
		PhoneNumber string `json:"phone_number"`
	}
}


type Response struct {
	Data struct {
		Payload Payload `json:"payload"`
	}
}


func main() {
  // extra code

  payload := Payload{
		From: struct {PhoneNumber string `json:"phone_number"`}(struct{ PhoneNumber string }{PhoneNumber: sender}),
		To: struct {PhoneNumber string `json:"phone_number"`}(struct{ PhoneNumber string }{PhoneNumber: recipient})}
	response := Response{Data: struct {
		Payload Payload `json:"payload"`
	}(struct{ Payload Payload }{Payload: payload})}
  fmt.Println(response)
}

The above response is:

{{{{+XXXXXXXXXX} {+XXXXXXXXXX}}}}

2. Raw dict creation:

var payload = map[string]interface{}{}
payload["from"].(map[string]string)["phone_number"] = sender
payload["to"].(map[string]string)["phone_number"] = recipient
fmt.Println(payload)

var response = map[string]interface{}{}
response["data"].(map[string]string)["payload"] = payload

Error: Cannot use 'payload' (type map[string]interface{}) as the type string

I would highly appreciate it if you could guide me in the correct direction

The simplest way is to use the Convert JSON to Go struct, that generate a struct like:

type AutoGenerated struct {
	Data Data `json:"data"`
}
type From struct {
	PhoneNumber string `json:"phone_number"`
}
type To struct {
	PhoneNumber string `json:"phone_number"`
}
type Payload struct {
	From From `json:"from"`
	To   To   `json:"to"`
}
type Data struct {
	Payload Payload `json:"payload"`
}

and use, as example:

outStruct := AutoGenerated{
	Data: Data{
		Payload: Payload{
			From: From{PhoneNumber: sender},
			To:   To{PhoneNumber: recipient},
		},
	},
}
out, err := json.Marshal(outStruct)
fmt.Println(string(out), err)

this will out

{"data":{"payload":{"from":{"phone_number":"234234"},"to":{"phone_number":"32434"}}}} <nil>

Here is a working example of your code. When you were trying to create a raw map I think you were assigning value to nil map that's why you were getting error.

package main

import (
	"encoding/json"
	"fmt"
)

type (
	Response struct {
		Data Data `json:"data"`
	}

	Data struct {
		PayLoad PayLoad `json:"payload"`
	}

	PayLoad struct {
		From Address `json:"from"`
		To   Address `json:"to"`
	}

	Address struct {
		PhoneNumber string `json:"phone_number"`
	}
)

func main() {
	payload := PayLoad{
		From: Address{PhoneNumber: "+1xxxxxxxxx"},
		To:   Address{PhoneNumber: "+1xxxxxxxxx"},
	}

	resp := Response{
		Data: Data{
			PayLoad: payload,
		},
	}

	j, _ := json.Marshal(resp)
	fmt.Println(string(j))

	// with map

	var payloadNew = map[string]interface{}{
		"from": map[string]interface{}{
			"phone_number": "+1xxxxxxxx",
		},
		"to": map[string]interface{}{
			"phone_number": "+1yyyyyyyy",
		},
	}

	var responseNew = map[string]interface{}{
		"data": map[string]interface{}{
			"payload": payloadNew,
		},
	}

	j, _ = json.Marshal(responseNew)
	fmt.Println(string(j))
}

The json outputs are:

{"data":{"payload":{"from":{"phone_number":"+1xxxxxxxxx"},"to":{"phone_number":"+1xxxxxxxxx"}}}}
{"data":{"payload":{"from":{"phone_number":"+1xxxxxxxx"},"to":{"phone_number":"+1yyyyyyyy"}}}}