Read credential from $HOME/.db.json file.

        :type identifier: str
        :param identifier: str, database identifier.

        :type key_mapping: Dict[str, str]
        :param key_mapping: dict

        ``.db.json````::

            {
                "identifier1": {
                    "host": "example.com",
                    "port": 1234,
                    "database": "test",
                    "username": "admin",
                    "password": "admin",
                },
                "identifier2": {
                    ...
                }
            }

def from_home_db_json(cls, identifier, key_mapping=None):  # pragma: no cover
        """
        Read credential from $HOME/.db.json file.

        :type identifier: str
        :param identifier: str, database identifier.

        :type key_mapping: Dict[str, str]
        :param key_mapping: dict

        ``.db.json````::

            {
                "identifier1": {
                    "host": "example.com",
                    "port": 1234,
                    "database": "test",
                    "username": "admin",
                    "password": "admin",
                },
                "identifier2": {
                    ...
                }
            }
        """
        return cls.from_json(
            json_file=cls.path_db_json, json_path=identifier, key_mapping=key_mapping)