getBoardData(boardId) {
    const self = this;
    Meteor.subscribe('board', boardId, false, {
      onReady() {
        const sameBoardId = self.selectedBoardId.get() == boardId;
        self.selectedBoardId.set(boardId);

        if (!sameBoardId) {
          // reset swimlane id (for selection in cards())
          self.setFirstSwimlaneId();

          // reset list id (for selection in cards())
          self.setFirstListId();
        }
      },
    });
  }
get the board data from the server
@param boardId get the board data of this board id