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from configparser import ConfigParser |
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from typing import Dict, Optional, Union |
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from pystratum_backend.StratumStyle import StratumStyle |
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from pystratum_pgsql.PgSqlDefaultConnector import PgSqlDefaultConnector |
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from pystratum_pgsql.PgSqlMetadataDataLayer import PgSqlMetadataDataLayer |
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class PgSqlWorker: |
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""" |
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Class for connecting to PostgreSQL instances and reading PostgreSQL specific connection parameters from |
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configuration files. |
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""" |
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# ------------------------------------------------------------------------------------------------------------------ |
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def __init__(self, io: StratumStyle, config: ConfigParser): |
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""" |
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Object constructor. |
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:param PyStratumStyle io: The output decorator. |
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""" |
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self._io: StratumStyle = io |
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""" |
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The output decorator. |
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""" |
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self._config: ConfigParser = config |
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""" |
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The configuration object. |
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""" |
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self._dl = PgSqlMetadataDataLayer(io, PgSqlDefaultConnector(self.__read_configuration_file())) |
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""" |
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The metadata layer. |
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""" |
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# ------------------------------------------------------------------------------------------------------------------ |
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def connect(self) -> None: |
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""" |
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Connects to the PostgreSQL instance. |
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""" |
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self._dl.connect() |
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# ------------------------------------------------------------------------------------------------------------------ |
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def disconnect(self) -> None: |
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""" |
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Disconnects from the PostgreSQL instance. |
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""" |
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self._dl.disconnect() |
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# ------------------------------------------------------------------------------------------------------------------ |
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def __read_configuration_file(self) -> Dict[str, Union[str, int]]: |
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""" |
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Reads connections parameters from the configuration file. |
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""" |
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return {'host': self.__get_option(self._config, 'database', 'host', fallback='localhost'), |
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'user': self.__get_option(self._config, 'database', 'user'), |
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'password': self.__get_option(self._config, 'database', 'password'), |
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'database': self.__get_option(self._config, 'database', 'database'), |
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'schema': self.__get_option(self._config, 'database', 'schema'), |
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'port': int(self.__get_option(self._config, 'database', 'port', fallback='5432'))} |
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# ------------------------------------------------------------------------------------------------------------------ |
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@staticmethod |
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def __get_option(config: ConfigParser, |
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section: str, |
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option: str, |
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fallback: Optional[str] = None) -> str: |
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""" |
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Reads an option for a configuration file. |
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:param configparser.ConfigParser config: The main config file. |
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:param str section: The name of the section op the option. |
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:param str option: The name of the option. |
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:param str|None fallback: The fallback value of the option if it is not set in either configuration files. |
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:rtype: str |
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:raise KeyError: |
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""" |
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return_value = config.get(section, option, fallback=fallback) |
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if fallback is None and return_value is None: |
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raise KeyError("Option '{0!s}' is not found in section '{1!s}'.".format(option, section)) |
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return return_value |
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# ---------------------------------------------------------------------------------------------------------------------- |
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DatabaseStratum /
py-stratum-pgsql
