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Mike Bayer
27 lines
1.0 KiB
Python
27 lines
1.0 KiB
Python
"""
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Illustrates "vertical table" mappings.
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A "vertical table" refers to a technique where individual attributes of an object are stored as distinct rows in a table.
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The "vertical table" technique is used to persist objects which can have a varied set of attributes, at the expense of simple query control and brevity. It is commonly found in content/document management systems in order to represent user-created structures flexibly.
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Two variants on the approach are given. In the second, each row references a "datatype" which contains information about the type of information stored in the attribute, such as integer, string, or date.
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Example::
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shrew = Animal(u'shrew')
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shrew[u'cuteness'] = 5
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shrew[u'weasel-like'] = False
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shrew[u'poisonous'] = True
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session.add(shrew)
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session.flush()
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q = (session.query(Animal).
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filter(Animal.facts.any(
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and_(AnimalFact.key == u'weasel-like',
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AnimalFact.value == True))))
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print 'weasel-like animals', q.all()
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""" |