How to process variable input JSON with Golang Gin

I trying to write my first app on Gin with Golang
There is some service that post some variable JSON to controller
Input data like this:

{
  "shipping:{
    "address_id1": {..some data..},
    "address_id2": {..some data..}
  },
  "items": {
    "item_id1": {..some data..},
    "item_id2": {..some data..}
  }
}

So, I don't know items keys and I need to process through items array
How can I do it with Gin?
In PHP I will walk through associative array like

foreach ($_POST['shipping'] as $key => $value) {
  ..some logic with data..
}

In other words, how to work with input posted data correctly?

In Go-Gin we can use Bind() or BindJSON() of Gin's context object to access the data which is posted as JSON.

You can use a nested map when the keys are unknown.

type Shipping map[string]map[string]string
type Items map[string]map[string]string

type RequestPayload struct {
	Shipping Shipping `json:"shipping"`
	Items    Items    `json:"items"`
}

// controller
func ShippingController(ctx *gin.Context) {
	var request RequestPayload
	if err := ctx.BindJSON(&request); err != nil {
		panic(err)
	}

	for key, value := range request.Items {
		fmt.Println("The key : ", key)
		fmt.Println("The value : ", value)
	}

}