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"""Manager to read and modify config data in JSON files. |
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""" |
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from __future__ import annotations |
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import errno |
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import json |
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import os |
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from typing import Any |
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from traitlets.config import LoggingConfigurable |
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from traitlets.traitlets import Unicode |
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def recursive_update(target: dict[Any, Any], new: dict[Any, Any]) -> None: |
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"""Recursively update one dictionary using another. |
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None values will delete their keys. |
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""" |
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for k, v in new.items(): |
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if isinstance(v, dict): |
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if k not in target: |
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target[k] = {} |
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recursive_update(target[k], v) |
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if not target[k]: |
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del target[k] |
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elif v is None: |
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target.pop(k, None) |
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else: |
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target[k] = v |
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class BaseJSONConfigManager(LoggingConfigurable): |
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"""General JSON config manager |
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Deals with persisting/storing config in a json file |
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""" |
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config_dir = Unicode(".") |
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def ensure_config_dir_exists(self) -> None: |
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try: |
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os.makedirs(self.config_dir, 0o755) |
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except OSError as e: |
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if e.errno != errno.EEXIST: |
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raise |
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def file_name(self, section_name: str) -> str: |
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return os.path.join(self.config_dir, section_name + ".json") |
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def get(self, section_name: str) -> Any: |
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"""Retrieve the config data for the specified section. |
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Returns the data as a dictionary, or an empty dictionary if the file |
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doesn't exist. |
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""" |
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filename = self.file_name(section_name) |
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if os.path.isfile(filename): |
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with open(filename, encoding="utf-8") as f: |
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return json.load(f) |
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else: |
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return {} |
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def set(self, section_name: str, data: Any) -> None: |
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"""Store the given config data.""" |
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filename = self.file_name(section_name) |
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self.ensure_config_dir_exists() |
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with open(filename, "w", encoding="utf-8") as f: |
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json.dump(data, f, indent=2) |
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def update(self, section_name: str, new_data: Any) -> Any: |
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"""Modify the config section by recursively updating it with new_data. |
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Returns the modified config data as a dictionary. |
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""" |
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data = self.get(section_name) |
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recursive_update(data, new_data) |
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self.set(section_name, data) |
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return data |
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