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

_examples/real-world-examples/server-sent-events-htmx/events.go

@@ -0,0 +1,190 @@
+package main
+
+import (
+	"context"
+	"fmt"
+	"time"
+
+	"cloud.google.com/go/pubsub/v2/apiv1/pubsubpb"
+	"github.com/ThreeDotsLabs/watermill"
+	"github.com/ThreeDotsLabs/watermill-googlecloud/v2/pkg/googlecloud"
+	"github.com/ThreeDotsLabs/watermill-http/v2/pkg/http"
+	"github.com/ThreeDotsLabs/watermill/components/cqrs"
+	"github.com/ThreeDotsLabs/watermill/message"
+	"github.com/ThreeDotsLabs/watermill/message/router/middleware"
+	"google.golang.org/protobuf/types/known/durationpb"
+)
+
+type PostViewed struct {
+	PostID int `json:"post_id"`
+}
+
+type PostReactionAdded struct {
+	PostID     int    `json:"post_id"`
+	ReactionID string `json:"reaction_id"`
+}
+
+type PostStatsUpdated struct {
+	PostID          int            `json:"post_id"`
+	Views           int            `json:"views"`
+	ViewsUpdated    bool           `json:"views_updated"`
+	Reactions       map[string]int `json:"reactions"`
+	ReactionUpdated *string        `json:"reaction_updated"`
+}
+
+type Routers struct {
+	EventsRouter *message.Router
+	SSERouter    http.SSERouter
+	EventBus     *cqrs.EventBus
+}
+
+func NewRouters(cfg config, repo *Repository) (Routers, error) {
+	logger := watermill.NewStdLogger(false, false)
+
+	publisher, err := googlecloud.NewPublisher(
+		googlecloud.PublisherConfig{
+			ProjectID: cfg.PubSubProjectID,
+		},
+		logger,
+	)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	eventBus, err := cqrs.NewEventBusWithConfig(
+		publisher,
+		cqrs.EventBusConfig{
+			GeneratePublishTopic: func(params cqrs.GenerateEventPublishTopicParams) (string, error) {
+				return params.EventName, nil
+			},
+			Marshaler: cqrs.JSONMarshaler{},
+			Logger:    logger,
+		},
+	)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	eventsRouter, err := message.NewRouter(message.RouterConfig{}, logger)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	eventsRouter.AddMiddleware(middleware.Recoverer)
+
+	eventProcessor, err := cqrs.NewEventProcessorWithConfig(
+		eventsRouter,
+		cqrs.EventProcessorConfig{
+			GenerateSubscribeTopic: func(params cqrs.EventProcessorGenerateSubscribeTopicParams) (string, error) {
+				return params.EventName, nil
+			},
+			SubscriberConstructor: func(params cqrs.EventProcessorSubscriberConstructorParams) (message.Subscriber, error) {
+				return googlecloud.NewSubscriber(
+					googlecloud.SubscriberConfig{
+						ProjectID: cfg.PubSubProjectID,
+						GenerateSubscriptionName: func(topic string) string {
+							return fmt.Sprintf("%v_%v", topic, params.HandlerName)
+						},
+					},
+					logger,
+				)
+			},
+			Marshaler: cqrs.JSONMarshaler{},
+			Logger:    logger,
+		},
+	)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	err = eventProcessor.AddHandlers(
+		cqrs.NewEventHandler(
+			"UpdateViews",
+			func(ctx context.Context, event *PostViewed) error {
+				var views int
+				var reactions map[string]int
+				err = repo.UpdatePost(ctx, event.PostID, func(post *Post) {
+					post.Views++
+					views = post.Views
+					reactions = post.Reactions
+				})
+				if err != nil {
+					return err
+				}
+
+				statsUpdated := PostStatsUpdated{
+					PostID:       event.PostID,
+					ViewsUpdated: true,
+					Views:        views,
+					Reactions:    reactions,
+				}
+
+				return eventBus.Publish(ctx, statsUpdated)
+			},
+		),
+		cqrs.NewEventHandler(
+			"UpdateReactions",
+			func(ctx context.Context, event *PostReactionAdded) error {
+				var views int
+				var reactions map[string]int
+				err := repo.UpdatePost(ctx, event.PostID, func(post *Post) {
+					post.Reactions[event.ReactionID]++
+					views = post.Views
+					reactions = post.Reactions
+				})
+				if err != nil {
+					return err
+				}
+
+				statsUpdated := PostStatsUpdated{
+					PostID:          event.PostID,
+					Views:           views,
+					ReactionUpdated: &event.ReactionID,
+					Reactions:       reactions,
+				}
+
+				return eventBus.Publish(ctx, statsUpdated)
+			},
+		),
+	)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	sseSubscriber, err := googlecloud.NewSubscriber(
+		googlecloud.SubscriberConfig{
+			ProjectID: cfg.PubSubProjectID,
+			GenerateSubscriptionName: func(topic string) string {
+				return fmt.Sprintf("%v_%v", topic, watermill.NewShortUUID())
+			},
+			GenerateSubscription: func(params googlecloud.GenerateSubscriptionParams) *pubsubpb.Subscription {
+				return &pubsubpb.Subscription{
+					ExpirationPolicy: &pubsubpb.ExpirationPolicy{
+						Ttl: durationpb.New(time.Hour * 24),
+					},
+				}
+			},
+		},
+		logger,
+	)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	sseRouter, err := http.NewSSERouter(
+		http.SSERouterConfig{
+			UpstreamSubscriber: sseSubscriber,
+			Marshaler:          http.StringSSEMarshaler{},
+		},
+		logger,
+	)
+	if err != nil {
+		return Routers{}, err
+	}
+
+	return Routers{
+		EventsRouter: eventsRouter,
+		SSERouter:    sseRouter,
+		EventBus:     eventBus,
+	}, nil
+}