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119 lines
4.7 KiB
Python
119 lines
4.7 KiB
Python
import os
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import configparser
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class ConfigLoader:
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"""
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The :class:`ConfigLoader` class is in charge of loading all the configuration parameters to create a config dict
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that can be used to set all configurable parameters of the system.
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Args:
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data_dir (:obj:`str`): the path to the data directory where the configuration file may be found.
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default_conf (:obj:`dict`): a dictionary populated with the default configuration params and the expected types.
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The format is as follows:
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{"field0": {"value": value_from_conf_file, "type": expected_type, ...}}
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command_line_conf (:obj:`dict`): a dictionary containing the command line parameters that may replace the
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ones in default / config file.
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Attributes:
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data_dir (:obj:`str`): the path to the data directory where the configuration file may be found.
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conf_file_path (:obj:`str`): the path to the config file (the file may not exist).
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conf_fields (:obj:`dict`): a dictionary populated with the configuration params and the expected types.
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It follows the same format as default_conf.
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command_line_conf (:obj:`dict`): a dictionary containing the command line parameters that may replace the
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ones in default / config file.
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"""
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def __init__(self, data_dir, conf_file_name, default_conf, command_line_conf):
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self.data_dir = data_dir
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self.conf_file_path = os.path.join(self.data_dir, conf_file_name)
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self.conf_fields = default_conf
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self.command_line_conf = command_line_conf
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self.overwritten_fields = set()
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def build_config(self):
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"""
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Builds a config dictionary from command line, config file and default configuration parameters.
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The priority is as follows:
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- command line
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- config file
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- defaults
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Returns:
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:obj:`dict`: a dictionary containing all the configuration parameters.
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"""
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if os.path.exists(self.conf_file_path):
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file_config = configparser.ConfigParser()
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file_config.read(self.conf_file_path)
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# Load parameters and cast them to int if necessary
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if file_config:
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for sec in file_config.sections():
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for k, v in file_config.items(sec):
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k_upper = k.upper()
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if k_upper in self.conf_fields:
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if self.conf_fields[k_upper]["type"] == int:
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try:
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self.conf_fields[k_upper]["value"] = int(v)
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except ValueError:
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err_msg = "{} is not an integer ({}).".format(k, v)
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raise ValueError(err_msg)
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else:
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self.conf_fields[k_upper]["value"] = v
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self.overwritten_fields.add(k_upper)
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# Override the command line parameters to the defaults / conf file
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for k, v in self.command_line_conf.items():
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self.conf_fields[k]["value"] = v
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self.overwritten_fields.add(k)
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# Extend relative paths
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self.extend_paths()
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# Sanity check fields and build config dictionary
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config = self.create_config_dict()
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return config
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def create_config_dict(self):
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"""
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Checks that the configuration fields (self.conf_fields) have the right type and creates a config dict if so.
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Returns:
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:obj:`dict`: A dictionary with the same keys as the provided one, but containing only the "value" field as
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value if the provided ``conf_fields`` are correct.
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Raises:
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:obj:`ValueError`: If any of the dictionary elements does not have the expected type.
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"""
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conf_dict = {}
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for field in self.conf_fields:
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value = self.conf_fields[field]["value"]
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correct_type = self.conf_fields[field]["type"]
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if isinstance(value, correct_type):
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conf_dict[field] = value
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else:
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err_msg = "{} variable in config is of the wrong type".format(field)
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raise ValueError(err_msg)
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return conf_dict
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def extend_paths(self):
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"""
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Extends the relative paths of the ``conf_fields`` dictionary with ``data_dir``.
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If an absolute path is given, it'll remain the same.
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"""
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for key, field in self.conf_fields.items():
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if field.get("path") and isinstance(field.get("value"), str):
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self.conf_fields[key]["value"] = os.path.join(self.data_dir, self.conf_fields[key]["value"])
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