如何从数据库获取寄存器，然后绑定请求而不删除数据

I need to do an Update for a table on PG. The request have some columns or fields in the table. First Bind the request to an instance, but when I get the entity from DB then delete all data from request. I prefer to validate the data of the structure before obtaining the data from the database.

package main

import (
  "log"

  "bitbucket.org/company/app/controllers"
  "bitbucket.org/company/gobase/rest"
)

func main() {
  server, routes := rest.NewServer(prefixPath) 
  routes.POST("/data/:id", controllers.Update)
}

The model

type Data struct {
    tableName struct{} `sql:"data"`

    ID        int       `sql:"id,pk"      json:"id"`
    CreatedAt time.Time `sql:"created_at" json:"created_at"`
    Column1   string    `sql:"column1"    json:"column1"`
    Column2   string    `sql:"column2"    json:"column2"`
    Column3   time.Time `sql:"column3"    json:"column3"`
}

The Controller:

func Update(c echo.Context) (err error) {
    id, err := strconv.Atoi(c.Param("id"))
    if err != nil {
        return c.JSON(http.StatusBadRequest, err)
    }

    data := Data{}
    if err = c.Bind(&data); err != nil {
        return c.JSON(http.StatusBadRequest, err)
    }

    err := db().Table("data").
      Where("id = ?", id).
      Select(&data)
    if err != nil {
      return c.JSON(http.StatusNotFound, err)
    }

    , err := db(data).
      Where("id = ?", data.ID).
      Update(data)
    if err != nil {
      return c.JSON(http.StatusInternalServerError, err)
    }

    return c.JSON(http.StatusOK, userSocial)
}

If I look for the entity in the bd first and then I Bind the request to the entity, it works perfectly, it only updates the request fields. But I prefer to validate the structure of the request before searching the database.