migrate/driver/mongodb/gomethods/gomethods_registry.go

package gomethods

import (
	"fmt"
	"sync"

	"gopkg.in/mattes/migrate.v1/driver"
)

var methodsReceiversMu sync.Mutex

// Registers a methods receiver for go methods driver
// Users of gomethods migration drivers should call this method
// to register objects with their migration methods before executing the migration
func RegisterMethodsReceiverForDriver(driverName string, receiver interface{}) {
	methodsReceiversMu.Lock()
	defer methodsReceiversMu.Unlock()
	if receiver == nil {
		panic("Go methods: Register receiver object is nil")
	}

	driver := driver.GetDriver(driverName)
	if driver == nil {
		panic("Go methods: Trying to register receiver for not registered driver " + driverName)
	}

	methodsDriver, ok := driver.(GoMethodsDriver)
	if !ok {
		panic("Go methods: Trying to register receiver for non go methods driver " + driverName)
	}

	if methodsDriver.MethodsReceiver() != nil {
		panic("Go methods: Methods receiver already registered for driver " + driverName)
	}

	if err := methodsDriver.SetMethodsReceiver(receiver); err != nil {
		panic(fmt.Sprintf("Go methods: Failed to set methods receiver for driver %s\nError: %v",
			driverName, err))
	}
}