fix the bugs that were causing mutation response errors, and add duplicate subscription checks

MUTATIONS WORK BTW!!!

engine.go

@@ -176,8 +176,15 @@ func (e *Engine) ExecuteQuery(query string, params map[string]interface{}, clien
 	return result, nil
 }
 
-func (e *Engine) ExecuteMutation(mutation string, params map[string]interface{}, clientID string) (interface{}, error) {
+func (e *Engine) ExecuteMutation(mutation string, params map[string]interface{}, clientID string, mutationID string) (interface{}, error) {
 	result := e.mutations[mutation](&MutationCtx{DB: e.db, AuthCtx: &AuthCtx{UserID: "", IsLoggedIn: true}, Params: params})
+	slog.Debug("Executing mutation", "mutation", mutation, "params", params, "result", result)
+	responseJSON, err := json.Marshal(map[string]interface{}{"type": "mutation", "location": mutation, "data": result, "mutation_id": mutationID})
+	if err != nil {
+		slog.Error("Failed to encode mutation result", "mutation", mutation, "error", err)
+		return nil, err
+	}
+	e.tracker.SendMessage(clientID, responseJSON)
 	return result, nil
 }
 
@@ -192,7 +199,7 @@ func (e *Engine) OnReceiveMessage(clientID string, msg map[string]interface{}) e
 		e.tracker.SubscribeToQuery(clientID, msg["location"].(string), string(paramsJSON))
 		e.ExecuteQuery(msg["location"].(string), msg["params"].(map[string]interface{}), clientID, true)
 	case "mutation":
-		e.ExecuteMutation(msg["location"].(string), msg["params"].(map[string]interface{}), clientID)
+		e.ExecuteMutation(msg["location"].(string), msg["params"].(map[string]interface{}), clientID, msg["mutation_id"].(string))
 	}
 	return nil
 }

example/client/index.ts

@@ -16,6 +16,7 @@ const rl = createInterface({
 while (true) {
   const message = await rl.question("Enter a message");
   if (message) {
-    client.sendMutation("createMessage", { room: "1", message: message });
+    const result = await client.sendMutation("createMessage", { room: "1", message: message });
+    console.log("Mutation result", result);
   }
 }

example/client/package-lock.json

@@ -28,7 +28,7 @@
     },
     "node_modules/tether-ts": {
       "version": "1.0.3",
-      "resolved": "git+ssh://git@github.com/wisplite/tether-ts.git#8945de00ece92ce1e939a3ff70c5312f80e56dda",
+      "resolved": "git+ssh://git@github.com/wisplite/tether-ts.git#82a462ee116789dd6832fe5ff079a63fcb91afc4",
       "license": "ISC"
     },
     "node_modules/typescript": {

example/main.go

@@ -42,8 +42,11 @@ func main() {
 	}, []string{"messages"})
 
 	engine.RegisterMutation("createMessage", func(ctx *tether.MutationCtx) interface{} {
-		ctx.DB.Create(&Messages{ID: uuid.NewString(), Message: ctx.Params["message"].(string), SenderID: ctx.AuthCtx.UserID, RoomID: ctx.Params["room"].(string)})
+		msg := &Messages{ID: uuid.NewString(), Message: ctx.Params["message"].(string), SenderID: ctx.AuthCtx.UserID, RoomID: ctx.Params["room"].(string)}
-		return nil
+		if err := ctx.DB.Create(msg).Error; err != nil {
+			return map[string]interface{}{"error": err.Error()}
+		}
+		return msg
 	})
 
 	http.HandleFunc("/tether", engine.Handle)

reactivity/tracker.go

@@ -2,6 +2,7 @@ package reactivity
 
 import (
 	"log/slog"
+	"slices"
 	"sync"
 )
 
@@ -14,10 +15,15 @@ type Tracker struct {
 
 	// Maps a Query Hash (e.g. "getUser?id=1") to a Set of Client IDs
 	subscriptions       map[string][]map[string]string
+	clientSubscriptions map[string][]string
 }
 
 func NewTracker() *Tracker {
-	return &Tracker{clients: make(map[string]*Client), subscriptions: make(map[string][]map[string]string)}
+	return &Tracker{
+		clients:             make(map[string]*Client),
+		subscriptions:       make(map[string][]map[string]string),
+		clientSubscriptions: make(map[string][]string),
+	}
 }
 
 func (t *Tracker) Track(c *Client) {
@@ -30,6 +36,20 @@ func (t *Tracker) Untrack(c *Client) {
 	t.mu.Lock()
 	defer t.mu.Unlock()
 	delete(t.clients, c.ID)
+	delete(t.clientSubscriptions, c.ID)
+	for query, subs := range t.subscriptions {
+		kept := subs[:0]
+		for _, sub := range subs {
+			if sub["clientID"] != c.ID {
+				kept = append(kept, sub)
+			}
+		}
+		if len(kept) == 0 {
+			delete(t.subscriptions, query)
+		} else {
+			t.subscriptions[query] = kept
+		}
+	}
 }
 
 func (t *Tracker) SetAuthID(clientID string, authID string) {
@@ -39,6 +59,10 @@ func (t *Tracker) SetAuthID(clientID string, authID string) {
 }
 
 func (t *Tracker) GetAuthID(clientID string) string {
+	if _, ok := t.clients[clientID]; !ok {
+		slog.Error("Tracker: Client not found", "clientID", clientID)
+		return ""
+	}
 	return t.clients[clientID].GetAuthID()
 }
 
@@ -48,6 +72,13 @@ func (t *Tracker) SubscribeToQuery(clientID string, query string, params string)
 	if t.subscriptions[query] == nil {
 		t.subscriptions[query] = make([]map[string]string, 0)
 	}
+	if t.clientSubscriptions[clientID] == nil {
+		t.clientSubscriptions[clientID] = make([]string, 0)
+	}
+	if slices.Contains(t.clientSubscriptions[clientID], query) {
+		return // avoid duplicate subscriptions
+	}
+	t.clientSubscriptions[clientID] = append(t.clientSubscriptions[clientID], query)
 	// set t.subscriptions[query] to a map of client IDs and their params
 	t.subscriptions[query] = append(t.subscriptions[query], map[string]string{"clientID": clientID, "params": params})
 	slog.Debug("Tracker: Subscribed to query", "query", query, "clientID", clientID, "params", params)