feature: add API for listing all users

cmd/rest.go

@@ -19,6 +19,10 @@ func serve(config engine.ServerConfig) {
 		Doc("get the top list for a user").
 		Param(ws.PathParameter("user-id", "identifier of the user").DataType("int")).
 		Param(ws.FormParameter("number", "the number of recommendations").DataType("int")))
+	// Get user list
+	ws.Route(ws.GET("/users").
+		To(getUsers).
+		Doc("get the list of users"))
 	// Get user's feedback
 	ws.Route(ws.GET("/user/{user-id}").
 		To(getUser).
@@ -79,6 +83,15 @@ func getStatus(request *restful.Request, response *restful.Response) {
 	json(response, status)
 }
 
+func getUsers(request *restful.Request, response *restful.Response) {
+	users, err := db.GetUsers()
+	if err != nil {
+		internalServerError(response, err)
+		return
+	}
+	json(response, users)
+}
+
 func getUser(request *restful.Request, response *restful.Response) {
 	// Get user id
 	paramUserId := request.PathParameter("user-id")

engine/database.go

@@ -188,6 +188,23 @@ func (db *DB) GetFeedback() (users []int, items []int, feedback []float64, err e
 	return
 }
 
+func (db *DB) GetUsers() ([]int, error) {
+	var users []int
+	err := db.db.View(func(tx *bolt.Tx) error {
+		bucket := tx.Bucket([]byte(bktUserFeedback))
+		return bucket.ForEach(func(k, v []byte) error {
+			if v == nil {
+				users = append(users, decodeInt(k))
+			}
+			return nil
+		})
+	})
+	if err != nil {
+		return nil, err
+	}
+	return users, nil
+}
+
 func (db *DB) GetUserFeedback(userId int) ([]RecommendedItem, error) {
 	var items []RecommendedItem
 	err := db.db.View(func(tx *bolt.Tx) error {