Write Plugins

GORM itself is powered by Callbacks, so you could fully customize GORM as you want

Register a new callback

Register a callback into callbacks

func updateCreated(scope *Scope) {
  if scope.HasColumn("Created") {
    scope.SetColumn("Created", NowFunc())
  }
}

db.Callback().Create().Register("update_created_at", updateCreated)
// register a callback for Create process

Delete an existing callback

Delete a callback from callbacks

db.Callback().Create().Remove("gorm:create")
// delete callback `gorm:create` from Create callbacks

Replace an existing callback

Replace a callback having same name with new one

db.Callback().Create().Replace("gorm:create", newCreateFunction)
// replace callback `gorm:create` with new function `newCreateFunction` for Create process

Register callback orders

Register callbacks with orders

db.Callback().Create().Before("gorm:create").Register("update_created_at", updateCreated)
db.Callback().Create().After("gorm:create").Register("update_created_at", updateCreated)
db.Callback().Query().After("gorm:query").Register("my_plugin:after_query", afterQuery)
db.Callback().Delete().After("gorm:delete").Register("my_plugin:after_delete", afterDelete)
db.Callback().Update().Before("gorm:update").Register("my_plugin:before_update", beforeUpdate)
db.Callback().Create().Before("gorm:create").After("gorm:before_create").Register("my_plugin:before_create", beforeCreate)

Pre-Defined Callbacks

GORM has defiend callbacks to perform CRUD operations, check them out before start write your plugins

• Create callbacks

• Update callbacks

• Query callbacks

• Delete callbacks

• Row Query callbacks - no callbacks registered by default

Row Query callbacks will be called when perform Row or Rows, there are no registered callbacks by default, you could register a new one like:

func updateTableName(scope *gorm.Scope) {
  scope.Search.Table(scope.TableName() + "_draft") // append `_draft` to table name
}

db.Callback().RowQuery().Register("publish:update_table_name", updateTableName)

View https://godoc.org/github.com/jinzhu/gorm to view all available API