Fixed a bug where it was possible to add the same user multiple times to a team

models/error.go

@@ -450,3 +450,19 @@ func IsErrTeamAlreadyHasAccess(err error) bool {
 func (err ErrTeamAlreadyHasAccess) Error() string {
 	return fmt.Sprintf("This team already has access. [Team ID: %d, ID: %d]", err.TeamID, err.ID)
 }
+
+// ErrUserIsMemberOfTeam represents an error where a user is already member of a team.
+type ErrUserIsMemberOfTeam struct {
+	TeamID int64
+	UserID     int64
+}
+
+// IsErrUserIsMemberOfTeam checks if an error is ErrUserIsMemberOfTeam.
+func IsErrUserIsMemberOfTeam(err error) bool {
+	_, ok := err.(ErrUserIsMemberOfTeam)
+	return ok
+}
+
+func (err ErrUserIsMemberOfTeam) Error() string {
+	return fmt.Sprintf("This user is already a member of that team. [Team ID: %d, User ID: %d]", err.TeamID, err.UserID)
+}

models/team_members_create.go

@@ -14,6 +14,13 @@ func (tm *TeamMember) Create(doer *User) (err error) {
 		return
 	}
 
+	// Check if that user is already part of the team
+	exists, err := x.Where("team_id = ? AND user_id = ?", tm.TeamID, tm.UserID).
+		Get(&TeamMember{})
+	if exists {
+		return ErrUserIsMemberOfTeam{tm.TeamID, tm.UserID}
+	}
+
 	// Insert the user
 	_, err = x.Insert(tm)
 	return

routes/crud/create.go

@@ -56,6 +56,9 @@ func (c *WebHandler) CreateWeb(ctx echo.Context) error {
 		if models.IsErrTeamAlreadyHasAccess(err) {
 			return echo.NewHTTPError(http.StatusBadRequest, "This team already has access.")
 		}
+		if models.IsErrUserIsMemberOfTeam(err) {
+			return echo.NewHTTPError(http.StatusBadRequest, "This user is already a member of that team.")
+		}
 
 		return echo.NewHTTPError(http.StatusInternalServerError)
 	}