80 lines
2.3 KiB
Python
80 lines
2.3 KiB
Python
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import json
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from jsonpath_rw import parse
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class SafeDictSetter(object):
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""" Specialized write-only dictionary wrapper class that allows for setting
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nested keys via a path syntax.
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Example:
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sds = SafeDictSetter()
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sds['foo.bar.baz'] = 'hello' # Sets 'foo' = {'bar': {'baz': 'hello'}}
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sds['somekey'] = None # Does not set the key since the value is None
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"""
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def __init__(self, initial_object=None):
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self._object = initial_object or {}
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def __setitem__(self, path, value):
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self.set(path, value)
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def set(self, path, value, allow_none=False):
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""" Sets the value of the given path to the given value. """
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if value is None and not allow_none:
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return
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pieces = path.split('.')
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current = self._object
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for piece in pieces[:len(pieces)-1]:
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current_obj = current.get(piece, {})
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if not isinstance(current_obj, dict):
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raise Exception('Key %s is a non-object value: %s' % (piece, current_obj))
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current[piece] = current_obj
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current = current_obj
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current[pieces[-1]] = value
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def dict_value(self):
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""" Returns the dict value built. """
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return self._object
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def json_value(self):
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""" Returns the JSON string value of the dictionary built. """
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return json.dumps(self._object)
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class JSONPathDict(object):
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""" Specialized read-only dictionary wrapper class that uses the jsonpath_rw library
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to access keys via an X-Path-like syntax.
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Example:
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pd = JSONPathDict({'hello': {'hi': 'there'}})
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pd['hello.hi'] # Returns 'there'
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"""
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def __init__(self, dict_value):
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""" Init the helper with the JSON object.
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"""
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self._object = dict_value
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def __getitem__(self, path):
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def raise_exception():
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raise KeyError('Unknown path: %s' % path)
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return self.get(path, not_found_handler=raise_exception)
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def get(self, path, not_found_handler=None):
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""" Returns the value found at the given path. Path is a json-path expression. """
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jsonpath_expr = parse(path)
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matches = jsonpath_expr.find(self._object)
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if not matches:
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return not_found_handler() if not_found_handler else None
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match = matches[0].value
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if not match:
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return not_found_handler() if not_found_handler else None
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if isinstance(match, dict):
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return JSONPathDict(match)
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return match
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