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Use dot syntax to access dictionary key - Python Tips

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We can create our own class to use the dot syntax to access a dictionary's keys.

class DictX(dict): def __getattr__(self, key): try: return self[key] except KeyError as k: raise AttributeError(k) def __setattr__(self, key, value): self[key] = value def __delattr__(self, key): try: del self[key] except KeyError as k: raise AttributeError(k) def __repr__(self): return '<DictX ' + dict.__repr__(self) + '>'
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Our class DictX here inherit Python's builtin dict.

Now use it we just need to wrap a native dictionary with this DictX class:

data = DictX({ "name": "bo" }) # use dot to get print(data.name) print(data["name"]) # use dot to set data.state = "NY" print(data.state) print(data["state"]) # use dot to delete del data.state print(data)
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Printed result:

bo bo NY NY <DictX {'name': 'bo'}>
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Top comments (4)

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waylonwalker profile image
Waylon Walker •

This is such a fun example of how easy it is to be creative and make your own implementation of anything in python.

I often use simple namespaces or data classes to get this effect with vanilla types.

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anrodriguez profile image
An Rodriguez •

How would implement: foo["bar"]["baz"] to be equal to foo.bar.baz?

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bitecode profile image
BC •

You can try this, change the __getattr__ to:

def __getattr__(self, key): try: return self[key] except KeyError as k: self[key] = value = DictX() return value
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Then use it:

data = DictX() data.person.firstname = "bo" print(data.person.firstname) print(data["person"]["firstname"]) print(data)
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Result:

bo bo <DictX {'person': <DictX {'firstname': 'bo'}>}>
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zbigniew_rajewski_09546ca profile image
Zbigniew Rajewski • • Edited

It is always good to use builtins like SimpleNamespace. But if you really need something advanced to crawl through structures by dot notation then you should try Jsify library (citsystems.github.io/jsify/)