I need to load a list of database row objects into memory, and then grab one of those rows by its unique ID. Is there a clean, pythonic way of finding an single object from a list by an attribute value? Or do I just loop and compare?
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3Is there a reason to not doing this directly with a database query?Avaris– Avaris2012-02-01 00:45:38 +00:00Commented Feb 1, 2012 at 0:45
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3 Answers
Yes, you loop and compare:
items = [item for item in container if item.attribute == value]
And you get back a list which can be tested to see how many you found.
If you will be doing this a lot, consider using a dictionary, where the key is the attribute you're interested in.
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If you do this it only gives the very first match, instead of comparing the whole list: find first sequence item that matches a criterion.
If you do something like this, you don't have to catch the exception but get None instead:
item = next((i for i in items if i == 'value'), None)
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You can filter:
matches = filter(lambda obj: obj.attribute == "target value", myListOfObjects)
Refer to kindall's answer for advice on efficiency. If you're doing this a lot, it's not the right way.
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moeseth
what would be the right way to do so efficiently? Thanks.