mirror of
https://github.com/sqlalchemy/sqlalchemy.git
synced 2026-05-25 01:52:03 -04:00
Mike Bayer
18abd47af3
Applied on top of a pure run of black -l 79 in I7eda77fed3d8e73df84b3651fd6cfcfe858d4dc9, this set of changes resolves all remaining flake8 conditions for those codes we have enabled in setup.cfg. Included are resolutions for all remaining flake8 issues including shadowed builtins, long lines, import order, unused imports, duplicate imports, and docstring issues. Change-Id: I4f72d3ba1380dd601610ff80b8fb06a2aff8b0fe
80 lines
1.9 KiB
Python
80 lines
1.9 KiB
Python
"""
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illustrates a quick and dirty way to persist an XML document expressed using
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ElementTree and pickle.
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This is a trivial example using PickleType to marshal/unmarshal the ElementTree
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document into a binary column. Compare to explicit.py which stores the
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individual components of the ElementTree structure in distinct rows using two
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additional mapped entities. Note that the usage of both styles of persistence
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are identical, as is the structure of the main Document class.
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"""
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import os
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import sys
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from xml.etree import ElementTree
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from sqlalchemy import Column
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from sqlalchemy import create_engine
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from sqlalchemy import Integer
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from sqlalchemy import MetaData
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from sqlalchemy import PickleType
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from sqlalchemy import String
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from sqlalchemy import Table
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from sqlalchemy.orm import mapper
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from sqlalchemy.orm import Session
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e = create_engine("sqlite://")
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meta = MetaData()
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# setup a comparator for the PickleType since it's a mutable
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# element.
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def are_elements_equal(x, y):
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return x == y
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# stores a top level record of an XML document.
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# the "element" column will store the ElementTree document as a BLOB.
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documents = Table(
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"documents",
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meta,
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Column("document_id", Integer, primary_key=True),
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Column("filename", String(30), unique=True),
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Column("element", PickleType(comparator=are_elements_equal)),
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)
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meta.create_all(e)
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# our document class. contains a string name,
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# and the ElementTree root element.
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class Document(object):
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def __init__(self, name, element):
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self.filename = name
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self.element = element
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# setup mapper.
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mapper(Document, documents)
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# time to test !
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# get ElementTree document
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filename = os.path.join(os.path.dirname(__file__), "test.xml")
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doc = ElementTree.parse(filename)
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# save to DB
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session = Session(e)
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session.add(Document("test.xml", doc))
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session.commit()
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# restore
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document = session.query(Document).filter_by(filename="test.xml").first()
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# print
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document.element.write(sys.stdout)
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