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Adam Chainz
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60 lines
2.1 KiB
Python
60 lines
2.1 KiB
Python
"""
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Illustrates how to embed `dogpile.cache <https://dogpilecache.readthedocs.io/>`_
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functionality within
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the :class:`.Query` object, allowing full cache control as well as the
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ability to pull "lazy loaded" attributes from long term cache
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as well.
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.. versionchanged:: 0.8 The example was modernized to use
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dogpile.cache, replacing Beaker as the caching library in
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use.
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In this demo, the following techniques are illustrated:
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* Using custom subclasses of :class:`.Query`
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* Basic technique of circumventing Query to pull from a
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custom cache source instead of the database.
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* Rudimental caching with dogpile.cache, using "regions" which allow
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global control over a fixed set of configurations.
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* Using custom :class:`.MapperOption` objects to configure options on
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a Query, including the ability to invoke the options
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deep within an object graph when lazy loads occur.
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E.g.::
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# query for Person objects, specifying cache
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q = Session.query(Person).options(FromCache("default"))
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# specify that each Person's "addresses" collection comes from
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# cache too
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q = q.options(RelationshipCache(Person.addresses, "default"))
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# query
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print q.all()
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To run, both SQLAlchemy and dogpile.cache must be
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installed or on the current PYTHONPATH. The demo will create a local
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directory for datafiles, insert initial data, and run. Running the
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demo a second time will utilize the cache files already present, and
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exactly one SQL statement against two tables will be emitted - the
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displayed result however will utilize dozens of lazyloads that all
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pull from cache.
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The demo scripts themselves, in order of complexity, are run as Python
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modules so that relative imports work::
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python -m examples.dogpile_caching.helloworld
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python -m examples.dogpile_caching.relationship_caching
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python -m examples.dogpile_caching.advanced
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python -m examples.dogpile_caching.local_session_caching
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.. autosource::
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:files: environment.py, caching_query.py, model.py, fixture_data.py, \
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helloworld.py, relationship_caching.py, advanced.py, \
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local_session_caching.py
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"""
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