I now work restful api , but I have problem with my error to get all data from database , where I error is cannot display json , even though my query is working in ssms , but after I Implementing in my code but not working to display json

package main

import (
    "database/sql"
    "fmt"
    _ "github.com/denisenkom/go-mssqldb"
    "github.com/gin-gonic/gin"
    "net/http"
)

func main()  {
    db, err :=  sql.Open("sqlserver","sqlserver://sa:@localhost:1433?database=CONFINS&connection+timeout=30")
    if err != nil{
        fmt.Print(err.Error())
    }


    err = db.Ping()

    if err != nil {
        fmt.Print(err.Error())
    }
    defer db.Close()

    type SMSBlast struct {
        SequenceID  string
        MobilePhone string
        Output  string
        WillBeSentDate string
        SentDate string
        Status string
        DtmUpd string
    }

    router := gin.Default() 

//get all SMSBlast
    router.GET("/SMSBlast", func(context *gin.Context) {
        var(
            smsblast SMSBlast
            smsblasts []SMSBlast
        )
            rows, err :=  db.Query("select SequenceID,MobilePhone,Output,WillBeSentDate, SentDate, Status, DtmUpd from  SMSBlast2;")
            if err != nil{
                fmt.Print(err.Error())
            }
            for rows.Next(){
                err = rows.Scan(&smsblast.SequenceID, &smsblast.MobilePhone, &smsblast.Output, &smsblast.WillBeSentDate, &smsblast.SentDate, &smsblast.Status, &smsblast.DtmUpd)
                smsblasts = append(smsblasts, smsblast)
                if err != nil{
                    fmt.Print(err.Error())
                }
            }
            defer rows.Close()
            context.JSON(http.StatusOK, gin.H{
                "result" : smsblasts,
                "count"  :  len(smsblasts),
            })

    })

}