snapshot of https://github.com/ThreeDotsLabs/watermill.git (master, 2026-09-15; blobs > 131072B omitted)

components/cqrs/cqrs.go

@@ -0,0 +1,199 @@
+package cqrs
+
+import (
+	stdErrors "errors"
+
+	"github.com/ThreeDotsLabs/watermill"
+	"github.com/ThreeDotsLabs/watermill/message"
+	"github.com/pkg/errors"
+)
+
+// Deprecated: use CommandProcessor and EventProcessor instead.
+type FacadeConfig struct {
+	// GenerateCommandsTopic generates topic name based on the command name.
+	// Command name is generated by CommandEventMarshaler's Name method.
+	//
+	// It allows you to use topic per command or one topic for every command.
+	GenerateCommandsTopic func(commandName string) string
+
+	// CommandHandlers return command handlers which should be executed.
+	CommandHandlers func(commandBus *CommandBus, eventBus *EventBus) []CommandHandler
+
+	// CommandsPublisher is Publisher used to publish commands.
+	CommandsPublisher message.Publisher
+
+	// CommandsSubscriberConstructor is constructor for subscribers which will subscribe for messages.
+	// It will be called for every command handler.
+	// It allows you to create separated customized Subscriber for every command handler.
+	CommandsSubscriberConstructor CommandsSubscriberConstructor
+
+	// GenerateEventsTopic generates topic name based on the event name.
+	// Event name is generated by CommandEventMarshaler's Name method.
+	//
+	// It allows you to use topic per command or one topic for every command.
+	GenerateEventsTopic func(eventName string) string
+
+	// EventHandlers return event handlers which should be executed.
+	EventHandlers func(commandBus *CommandBus, eventBus *EventBus) []EventHandler
+
+	// EventsPublisher is Publisher used to publish commands.
+	EventsPublisher message.Publisher
+
+	// EventsSubscriberConstructor is constructor for subscribers which will subscribe for messages.
+	// It will be called for every event handler.
+	// It allows you to create separated customized Subscriber for every event handler.
+	EventsSubscriberConstructor EventsSubscriberConstructor
+
+	// Router is a Watermill router, which will be used to handle events and commands.
+	// Router handlers will be automatically generated by AddHandlersToRouter of Command and Event handlers.
+	Router *message.Router
+
+	CommandEventMarshaler CommandEventMarshaler
+
+	Logger watermill.LoggerAdapter
+}
+
+func (c FacadeConfig) Validate() error {
+	var err error
+
+	if c.CommandsEnabled() {
+		if c.GenerateCommandsTopic == nil {
+			err = stdErrors.Join(err, errors.New("GenerateCommandsTopic is nil"))
+		}
+		if c.CommandsSubscriberConstructor == nil {
+			err = stdErrors.Join(err, errors.New("CommandsSubscriberConstructor is nil"))
+		}
+		if c.CommandsPublisher == nil {
+			err = stdErrors.Join(err, errors.New("CommandsPublisher is nil"))
+		}
+	}
+	if c.EventsEnabled() {
+		if c.GenerateEventsTopic == nil {
+			err = stdErrors.Join(err, errors.New("GenerateEventsTopic is nil"))
+		}
+		if c.EventsSubscriberConstructor == nil {
+			err = stdErrors.Join(err, errors.New("EventsSubscriberConstructor is nil"))
+		}
+		if c.EventsPublisher == nil {
+			err = stdErrors.Join(err, errors.New("EventsPublisher is nil"))
+		}
+	}
+
+	if c.Router == nil {
+		err = stdErrors.Join(err, errors.New("Router is nil"))
+	}
+	if c.Logger == nil {
+		err = stdErrors.Join(err, errors.New("Logger is nil"))
+	}
+	if c.CommandEventMarshaler == nil {
+		err = stdErrors.Join(err, errors.New("CommandEventMarshaler is nil"))
+	}
+
+	return err
+}
+
+func (c FacadeConfig) EventsEnabled() bool {
+	return c.GenerateEventsTopic != nil || c.EventsPublisher != nil || c.EventsSubscriberConstructor != nil
+}
+
+func (c FacadeConfig) CommandsEnabled() bool {
+	return c.GenerateCommandsTopic != nil || c.CommandsPublisher != nil || c.CommandsSubscriberConstructor != nil
+}
+
+// Deprecated: use CommandHandler and EventHandler instead.
+//
+// Facade is a facade for creating the Command and Event buses and processors.
+// It was created to avoid boilerplate, when using CQRS in the standard way.
+// You can also create buses and processors manually, drawing inspiration from how it's done in NewFacade.
+type Facade struct {
+	commandsTopic func(commandName string) string
+	commandBus    *CommandBus
+
+	eventsTopic func(eventName string) string
+	eventBus    *EventBus
+
+	commandEventMarshaler CommandEventMarshaler
+}
+
+func (f Facade) CommandBus() *CommandBus {
+	return f.commandBus
+}
+
+func (f Facade) EventBus() *EventBus {
+	return f.eventBus
+}
+
+func (f Facade) CommandEventMarshaler() CommandEventMarshaler {
+	return f.commandEventMarshaler
+}
+
+// Deprecated: use CommandHandler and EventHandler instead.
+func NewFacade(config FacadeConfig) (*Facade, error) {
+	if err := config.Validate(); err != nil {
+		return nil, errors.Wrap(err, "invalid config")
+	}
+
+	c := &Facade{
+		commandsTopic:         config.GenerateCommandsTopic,
+		eventsTopic:           config.GenerateEventsTopic,
+		commandEventMarshaler: config.CommandEventMarshaler,
+	}
+
+	if config.CommandsEnabled() {
+		var err error
+		c.commandBus, err = NewCommandBus(
+			config.CommandsPublisher,
+			config.GenerateCommandsTopic,
+			config.CommandEventMarshaler,
+		)
+		if err != nil {
+			return nil, errors.Wrap(err, "cannot create command bus")
+		}
+	} else {
+		config.Logger.Info("Empty GenerateCommandsTopic, command bus will be not created", nil)
+	}
+	if config.EventsEnabled() {
+		var err error
+		c.eventBus, err = NewEventBus(config.EventsPublisher, config.GenerateEventsTopic, config.CommandEventMarshaler)
+		if err != nil {
+			return nil, errors.Wrap(err, "cannot create event bus")
+		}
+	} else {
+		config.Logger.Info("Empty GenerateEventsTopic, event bus will be not created", nil)
+	}
+
+	if config.CommandHandlers != nil {
+		commandProcessor, err := NewCommandProcessor(
+			config.CommandHandlers(c.commandBus, c.eventBus),
+			config.GenerateCommandsTopic,
+			config.CommandsSubscriberConstructor,
+			config.CommandEventMarshaler,
+			config.Logger,
+		)
+		if err != nil {
+			return nil, errors.Wrap(err, "cannot create command processor")
+		}
+
+		if err := commandProcessor.AddHandlersToRouter(config.Router); err != nil {
+			return nil, err
+		}
+	}
+	if config.EventHandlers != nil {
+		eventProcessor, err := NewEventProcessor(
+			config.EventHandlers(c.commandBus, c.eventBus),
+			config.GenerateEventsTopic,
+			config.EventsSubscriberConstructor,
+			config.CommandEventMarshaler,
+			config.Logger,
+		)
+		if err != nil {
+			return nil, errors.Wrap(err, "cannot create event processor")
+		}
+
+		if err := eventProcessor.AddHandlersToRouter(config.Router); err != nil {
+			return nil, err
+		}
+	}
+
+	return c, nil
+}