Added new API message endpoints (#291)

* Added new API endpoints

GET /sessions/{sessionId}/message - Fetches all messages from a session
PATCH /sessions/{sessionId}/messages - Allows modification of the
metadata on a session
GET /sessions/{sessionId}/messages/{messageId} - Gets a specific message
from a session

pkg/server/apihandlers/message_handlers.go

@@ -0,0 +1,176 @@
+package apihandlers
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+
+	log "github.com/sirupsen/logrus"
+
+	"github.com/getzep/zep/pkg/models"
+	"github.com/getzep/zep/pkg/server/handlertools"
+	"github.com/go-chi/chi/v5"
+	"github.com/google/uuid"
+)
+
+const DefaultMessageLimit = 100
+
+// UpdateMessageMetadataHandler updates the metadata of a specific message.
+//
+// This function handles HTTP PATCH requests at the /api/v1/session/{sessionId}/message/{messageId} endpoint.
+// It uses the session ID and message ID provided in the URL to find the specific message.
+// The new metadata is provided in the request body as a JSON object.
+//
+// The function updates the message's metadata with the new metadata and saves the updated message back to the database.
+// It then responds with the updated message as a JSON object.
+//
+// @Summary Updates the metadata of a specific message
+// @Description update message metadata by session id and message id
+// @Tags messages
+// @Accept json
+// @Produce json
+// @Param sessionId path string true "Session ID"
+// @Param messageId path string true "Message ID"
+// @Param body body models.Message true "New Metadata"
+// @Success 200 {object} Message
+// @Failure 404 {object} APIError "Not Found"
+// @Failure 500 {object} APIError "Internal Server Error"
+// @Router /api/v1/session/{sessionId}/message/{messageId} [patch]
+func UpdateMessageMetadataHandler(appState *models.AppState) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		sessionID := chi.URLParam(r, "sessionId")
+		messageUUID := handlertools.UUIDFromURL(r, w, "messageId")
+
+		log.Debugf("UpdateMessageMetadataHandler - SessionId %s - MessageUUID %s", sessionID, messageUUID)
+
+		message := models.Message{}
+		message.UUID = messageUUID
+		err := json.NewDecoder(r.Body).Decode(&message)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusBadRequest)
+			return
+		}
+
+		err = appState.MemoryStore.UpdateMessages(r.Context(), sessionID, []models.Message{message}, false, false)
+		if err != nil {
+			if errors.Is(err, models.ErrNotFound) {
+				handlertools.RenderError(w, fmt.Errorf("not found"), http.StatusNotFound)
+				return
+			} else {
+				handlertools.RenderError(w, err, http.StatusInternalServerError)
+				return
+			}
+		}
+
+		messages, err := appState.MemoryStore.GetMessagesByUUID(r.Context(), sessionID, []uuid.UUID{messageUUID})
+		if err != nil {
+			if errors.Is(err, models.ErrNotFound) {
+				handlertools.RenderError(w, fmt.Errorf("not found"), http.StatusNotFound)
+				return
+			} else {
+				handlertools.RenderError(w, err, http.StatusInternalServerError)
+				return
+			}
+		}
+
+		if err := handlertools.EncodeJSON(w, messages[0]); err != nil {
+			handlertools.RenderError(w, err, http.StatusInternalServerError)
+			return
+		}
+	}
+}
+
+// GetMessageHandler retrieves a specific message.
+//
+// This function handles HTTP GET requests at the /api/v1/session/{sessionId}/message/{messageId} endpoint.
+// It uses the session ID and message ID provided in the URL to find the specific message.
+//
+// The function responds with the found message as a JSON object.
+// If the session ID or message ID does not exist, the function responds with a 404 Not Found status code.
+// If there is an error while fetching the message, the function responds with a 500 Internal Server Error status code.
+//
+// @Summary Retrieves a specific message
+// @Description get message by session id and message id
+// @Tags messages
+// @Accept json
+// @Produce json
+// @Param sessionId path string true "Session ID"
+// @Param messageId path string true "Message ID"
+// @Success 200 {object} Message
+// @Failure 404 {object} APIError "Not Found"
+// @Failure 500 {object} APIError "Internal Server Error"
+// @Router /api/v1/session/{sessionId}/message/{messageId} [get]
+func GetMessageHandler(appState *models.AppState) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		sessionID := chi.URLParam(r, "sessionId")
+		messageUUID := handlertools.UUIDFromURL(r, w, "messageId")
+		log.Debugf("GetMessageHandler: sessionID: %s, messageID: %s", sessionID, messageUUID)
+
+		messageIDs := []uuid.UUID{messageUUID}
+		messages, err := appState.MemoryStore.GetMessagesByUUID(r.Context(), sessionID, messageIDs)
+		if err != nil {
+			if errors.Is(err, models.ErrNotFound) {
+				handlertools.RenderError(w, fmt.Errorf("not found"), http.StatusNotFound)
+				return
+			} else {
+				handlertools.RenderError(w, err, http.StatusInternalServerError)
+				return
+			}
+		}
+
+		if err := handlertools.EncodeJSON(w, messages[0]); err != nil {
+			handlertools.RenderError(w, err, http.StatusInternalServerError)
+			return
+		}
+	}
+}
+
+// GetMessagesForSessionHandler retrieves all messages for a specific session.
+//
+// This function handles HTTP GET requests at the /api/v1/session/{sessionId}/messages endpoint.
+// It uses the session ID provided in the URL to fetch all messages associated with that session.
+//
+// The function responds with a JSON array of messages. Each message in the array includes its ID, content, and metadata.
+// If the session ID does not exist, the function responds with a 404 Not Found status code.
+// If there is an error while fetching the messages, the function responds with a 500 Internal Server Error status code.
+//
+// @Summary Retrieves all messages for a specific session
+// @Description get messages by session id
+// @Tags messages
+// @Accept json
+// @Produce json
+// @Param sessionId path string true "Session ID"
+// @Success 200 {array} Message
+// @Failure 404 {object} APIError "Not Found"
+// @Failure 500 {object} APIError "Internal Server Error"
+// @Router /api/v1/session/{sessionId}/messages [get]
+func GetMessagesForSessionHandler(appState *models.AppState) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		sessionID := chi.URLParam(r, "sessionId")
+
+		var limit int
+		var err error
+		if limit, err = handlertools.IntFromQuery[int](r, "limit"); err != nil {
+			limit = DefaultMessageLimit
+		}
+
+		var cursor int
+		if cursor, err = handlertools.IntFromQuery[int](r, "cursor"); err != nil {
+			cursor = 1
+		}
+
+		log.Debugf("GetMessagesForSessionHandler - SessionId %s Limit %d Cursor %d", sessionID, limit, cursor)
+
+		messages, err := appState.MemoryStore.GetMessageList(r.Context(), sessionID, cursor, limit)
+		if err != nil {
+			handlertools.RenderError(w, err, http.StatusInternalServerError)
+			return
+		}
+
+		if err := handlertools.EncodeJSON(w, messages); err != nil {
+			handlertools.RenderError(w, err, http.StatusInternalServerError)
+			return
+		}
+	}
+}

pkg/server/routes.go

@@ -174,6 +174,16 @@ func setupSessionRoutes(router chi.Router, appState *models.AppState) {
 			r.Post("/", apihandlers.PostMemoryHandler(appState))
 			r.Delete("/", apihandlers.DeleteMemoryHandler(appState))
 		})
+
+		// Message-related routes
+		r.Route("/messages", func(r chi.Router) {
+			r.Get("/", apihandlers.GetMessagesForSessionHandler(appState))
+			r.Route("/{messageId}", func(r chi.Router) {
+				r.Get("/", apihandlers.GetMessageHandler(appState))
+				r.Patch("/", apihandlers.UpdateMessageMetadataHandler(appState))
+			})
+		})
+
 		// Memory search-related routes
 		r.Route("/search", func(r chi.Router) {
 			r.Post("/", apihandlers.SearchMemoryHandler(appState))

pkg/store/postgres/message.go

@@ -5,10 +5,11 @@ import (
 	"database/sql"
 	"errors"
 	"fmt"
+	"sync"
+
 	"github.com/getzep/zep/internal"
 	"github.com/getzep/zep/pkg/store"
 	"github.com/pgvector/pgvector-go"
-	"sync"
 
 	"github.com/getzep/zep/pkg/models"
 	"github.com/google/uuid"
@@ -253,9 +254,6 @@ func (dao *MessageDAO) GetListBySession(
 	ctx context.Context,
 	currentPage int,
 	pageSize int) (*models.MessageListResponse, error) {
-	if pageSize < 1 {
-		return nil, errors.New("pageSize must be greater than 0")
-	}
 
 	var wg sync.WaitGroup
 	var countErr error