Source code for ska_mid_dish_manager.utils.tango_helpers

"""This module provides utility functions for interacting with Tango devices."""

import logging
from typing import List, Optional

import tango


class TangoDbAccessor:
    """A class to access Tango device properties."""

    def __init__(self, logger: logging.Logger, tango_device_name: str):
        self._logger = logger
        self._tango_device_name = tango_device_name
        try:
            self._database = tango.Database()
        except tango.DevFailed as err:
            err_description = "".join([str(arg.desc) for arg in err.args])
            self._logger.error("Failed to connect to TangoDB: %s", err_description)
            # TODO handle case where tango db is a file
            # Question: does the tango.Database() api handle
            # file-based databases or only a SQL database?
            self._database = None

    def get_device_property_value(self, property_name: str) -> Optional[List[str]]:
        """Read device property value from TangoDB.

        :param property_name: Tango device property name
        :type property_name: str
        :return: value for the given property
        :rtype: Optional[str]
        """
        self._logger.debug("Getting device property value for %s.", property_name)
        try:
            device_properties = self._database.get_device_property(
                self._tango_device_name, property_name
            )
            property_values = device_properties.get(property_name)
            return property_values
        except tango.DevFailed as e:
            self._logger.error("Failed to read property %s: %s", property_name, e)
        except AttributeError:
            self._logger.error("Database connection is not available")
        return None

    def set_device_property_value(self, property_name: str, value: str) -> None:
        """Set a device property value in TangoDB.

        :param property_name: Tango device property name
        :type property_name: str
        :param value: Value to set for the property
        :type value: str
        """
        self._logger.debug("Setting device property %s to value %s.", property_name, value)
        try:
            self._database.put_device_property(self._tango_device_name, {property_name: value})
        except tango.DevFailed as e:
            self._logger.error("Failed to set property %s: %s", property_name, e)
        except AttributeError:
            self._logger.error("Database connection is not available")