def readOutput(self, directory, projectFileName, session, spatial=False, spatialReferenceID=None):
        """
        Read only output files for a GSSHA project to the database.

        Use this method to read a project when only post-processing tasks need to be performed.

        Args:
            directory (str): Directory containing all GSSHA model files. This method assumes that all files are located
                in the same directory.
            projectFileName (str): Name of the project file for the GSSHA model which will be read (e.g.: 'example.prj').
            session (:mod:`sqlalchemy.orm.session.Session`): SQLAlchemy session object bound to PostGIS enabled database
            spatial (bool, optional): If True, spatially enabled objects will be read in as PostGIS spatial objects.
                Defaults to False.
            spatialReferenceID (int, optional): Integer id of spatial reference system for the model. If no id is
                provided GsshaPy will attempt to automatically lookup the spatial reference ID. If this process fails,
                default srid will be used (4326 for WGS 84).
        """
        self.project_directory = directory
        with tmp_chdir(directory):
            # Add project file to session
            session.add(self)

            # Read Project File
            self.read(directory, projectFileName, session, spatial, spatialReferenceID)

            # Get the batch directory for output
            batchDirectory = self._getBatchDirectory(directory)

            # Read Mask (dependency of some output files)
            maskMap = WatershedMaskFile()
            maskMapFilename = self.getCard('WATERSHED_MASK').value.strip('"')
            maskMap.read(session=session, directory=directory, filename=maskMapFilename, spatial=spatial)
            maskMap.projectFile = self

            # Automatically derive the spatial reference system, if possible
            if spatialReferenceID is None:
                spatialReferenceID = self._automaticallyDeriveSpatialReferenceId(directory)

            # Read Output Files
            self._readXput(self.OUTPUT_FILES, batchDirectory, session, spatial=spatial, spatialReferenceID=spatialReferenceID)

            # Read WMS Dataset Files
            self._readWMSDatasets(self.WMS_DATASETS, batchDirectory, session, spatial=spatial, spatialReferenceID=spatialReferenceID)

            # Commit to database
            self._commit(session, self.COMMIT_ERROR_MESSAGE)