是否可以在GORM中使用动态JSON输入来运行db.AutoMigrate（）？

I have the following function in which I try to add missing columns to a PostgreSQL database's table with GORM. The data is coming from a HTTP request and is JSON.

router.POST("/up", func(c *gin.Context) {

    raw, _ := c.GetRawData()
    parsed, _ := gabs.ParseJSON(raw)

    db, err := gorm.Open("postgres", "host=" + os.Getenv("HOST") + " port=5432 user=" + os.Getenv("USER") + " dbname=something password=" + os.Getenv("PASSWORD"))

    [...]

    db.AutoMigrate(parsed.Data())

    defer db.Close()

})

This fails with a strange error (German).

(pq: Bezeichner in Anführungszeichen hat Länge null bei »""«)

Which translated means the following.

(pq: Quoted identifier has a length of zero at »""«)

The JSON I create the HTTP request with looks like this.

{
  "FieldA": "blah",
  "FieldB": "nope",
  "Hostname": "yo.host.com",
  "Updated": "2018.06.13 21:00:33"
}

Any ideas how to do this? The idea is to add a column to the db each time a new field is sent to the backend.