Logger

Gorm has a default logger implementation, it will print Slow SQL and happening errors by default

The logger accepts few options, you can customize it during initialization, for example:

newLogger := logger.New(
  log.New(os.Stdout, "\r\n", log.LstdFlags), // io writer
  logger.Config{
    SlowThreshold:              time.Second,   // Slow SQL threshold
    LogLevel:                   logger.Silent, // Log level
    IgnoreRecordNotFoundError: true,           // Ignore ErrRecordNotFound error for logger
    ParameterizedQueries:      true,           // Don't include params in the SQL log
    Colorful:                  false,          // Disable color
  },
)
// Globally mode
db, err := gorm.Open(sqlite.Open("test.db"), &gorm.Config{
  Logger: newLogger,
})
// Continuous session mode
tx := db.Session(&Session{Logger: newLogger})
tx.First(&user)
tx.Model(&user).Update("Age", 18)

Log Levels

GORM defined log levels: Silent, Error, Warn, Info

db, err := gorm.Open(sqlite.Open("test.db"), &gorm.Config{
  Logger: logger.Default.LogMode(logger.Silent),
})

Debug

Debug a single operation, change current operation’s log level to logger.Info

db.Debug().Where("name = ?", "jinzhu").First(&User{})

Customize Logger

Refer to GORM’s default logger for how to define your own one

The logger needs to implement the following interface, it accepts context, so you can use it for log tracing

type Interface interface {
  LogMode(LogLevel) Interface
  Info(context.Context, string, ...interface{})
  Warn(context.Context, string, ...interface{})
  Error(context.Context, string, ...interface{})
  Trace(ctx context.Context, begin time.Time, fc func() (sql string, rowsAffected int64), err error)
}