Raw SQLs having whitespace(s) as prefix are going to write DB

[shudipta]

GORM Playground Link

go-gorm/playground#239

Description

While using gorm.io/plugin/dbresolver to split read-write, raw query having whitespace(s) as prefix should go to read server.

import (
  "gorm.io/gorm"
  "gorm.io/plugin/dbresolver"
  "gorm.io/driver/mysql"
)

DB, err := gorm.Open(mysql.Open("db1_dsn"), &gorm.Config{})

DB.Use(dbresolver.Register(dbresolver.Config{
  // use `db1` as sources, `db2` as replicas for 
  Sources:  []gorm.Dialector{mysql.Open("db1_dsn")},
  Replicas: []gorm.Dialector{mysql.Open("db2_dsn")}
}, "users"))


// ...

readDB, err := gorm.Open(mysql.Open("db2_dsn"), &gorm.Config{})
if err != nil {
  // handle error
}

readDB.Create(&User{Name: "read"})

// this query should go to the read db with db2_dsn
DB.Raw(`
select name from users
where name = ?
`, "read").Row().Scan(&name)

This query should go to the read db with db2_dsn, but the current dbresolver sends it to the write db with db1_dsn.

[shudipta]

cc: @nixon1333