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`dir(object)` is a useful Python function that tells you what attributes and methods an object has. It’s also used by tools like iPython and IDEs for code completion. Some of the attributes of a `JSONModel` are dynamic, based on what fields we expect in the underlying JSON. Therefore they don’t automatically end up in the result of calling `dir`. To get around this we can implement our own `__dir__` method, which also returns the names of the fields we’re expecting the the JSON. Inspired by this Raymond Hettinger tweet: > #python tip: If you add attributes to an API with __getattr__() or > __getattribute__(), remember to update __dir__() to make the extension > introspectable. — https://twitter.com/raymondh/status/1249860863525146624
83 lines
2.0 KiB
Python
83 lines
2.0 KiB
Python
from abc import ABC, abstractmethod
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from collections.abc import Sequence
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from flask import abort
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class JSONModel():
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ALLOWED_PROPERTIES = set()
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def __init__(self, _dict):
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# in the case of a bad request _dict may be `None`
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self._dict = _dict or {}
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def __bool__(self):
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return self._dict != {}
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def __hash__(self):
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return hash(self.id)
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def __dir__(self):
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return super().__dir__() + list(sorted(self.ALLOWED_PROPERTIES))
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def __eq__(self, other):
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return self.id == other.id
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def __getattribute__(self, attr):
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try:
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return super().__getattribute__(attr)
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except AttributeError as e:
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# Re-raise any `AttributeError`s that are not directly on
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# this object because they indicate an underlying exception
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# that we don’t want to swallow
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if str(e) != "'{}' object has no attribute '{}'".format(
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self.__class__.__name__, attr
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):
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raise e
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if attr in super().__getattribute__('ALLOWED_PROPERTIES'):
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return super().__getattribute__('_dict')[attr]
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raise AttributeError((
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"'{}' object has no attribute '{}' and '{}' is not a field "
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"in the underlying JSON"
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).format(
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self.__class__.__name__, attr, attr
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))
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def _get_by_id(self, things, id):
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try:
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return next(thing for thing in things if thing['id'] == str(id))
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except StopIteration:
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abort(404)
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class ModelList(ABC, Sequence):
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@property
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@abstractmethod
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def client_method(self):
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pass
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@property
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@abstractmethod
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def model(self):
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pass
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def __init__(self, *args):
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self.items = self.client_method(*args)
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def __getitem__(self, index):
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return self.model(self.items[index])
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def __len__(self):
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return len(self.items)
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def __add__(self, other):
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return list(self) + list(other)
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def __radd__(self, other):
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return list(other) + list(self)
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