Sample using gin's BindJSON

main.go

package main

import (
	"fmt"
	"log"

	"github.com/gin-gonic/gin"
)

type CreateParams struct {
	Username     string   `json:"username"`
	Guests       []Person `json:"guests"`
	RoomType     string   `json:"roomType"`
	CheckinDate  string   `json:"checkinDate"`
	CheckoutDate string   `json:"checkoutDate"`
}

type Person struct {
	Firstname string `json:"firstname"`
	Lastname  string `json:"lastname"`
}

func main() {
	r := gin.Default()

	r.POST("/", func(c *gin.Context) {
		var createParams CreateParams
		err := c.BindJSON(&createParams)
		if err != nil {
			log.Fatal(err)
		}
		fmt.Println(createParams)
	})

	r.Run(":8000")

	// request
	// curl http://localhost:8000 -d @request.json
}

request.json

{
	"guests": [
		{
			"firstname": "ryan",
			"lastname": "vlaming"
		}
	],
	"roomType": "suite",
	"checkinDate": "2018-04-13T19:24:00+00:00",
	"checkoutDate": "2018-07-13T19:24:00+00:00"
}

@boddumanohar
I don't know because I haven't written Golang for about 2 years, but when I read the source code, c.BindJSON passes the HTTP status code 400 to the context and then returns a pointer or an error. Internally, the decoder of the json package I'm implementing using.
You can understand it by reading the following.

BindJSON: https://github.com/gin-gonic/gin/blob/e899771392ecf35de8ce10a030ed8fed2207e9cb/context.go#L608

context has 400 status code when if an error occurs

https://github.com/gin-gonic/gin/blob/e899771392ecf35de8ce10a030ed8fed2207e9cb/context.go#L647

decodeJSON: https://github.com/gin-gonic/gin/blob/e899771392ecf35de8ce10a030ed8fed2207e9cb/binding/json.go#L44

If you added 'required' tag in your struct, then in JsonBind you will receive an error