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import logging
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from itertools import count
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from sqlalchemy.sql import expression, and_
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log = logging.getLogger(__name__)
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def resultiter(rp):
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""" SQLAlchemy ResultProxies are not iterable to get a
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list of dictionaries. This is to wrap them. """
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keys = rp.keys()
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while True:
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row = rp.fetchone()
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if row is None:
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break
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yield dict(zip(keys, row))
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def find_one(engine, table, **kw):
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res = list(find(engine, table, _limit=1, **kw))
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if not len(res):
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return None
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return res[0]
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def find(engine, table, _limit=None, _step=5000, _offset=0,
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order_by=None, **kw):
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if order_by is None:
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order_by = [table.c.id.asc()]
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qargs = []
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try:
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for col, val in kw.items():
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qargs.append(table.c[col]==val)
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except KeyError:
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return
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for i in count():
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qoffset = _offset + (_step * i)
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qlimit = _step
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if _limit is not None:
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qlimit = min(_limit-(_step*i), _step)
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if qlimit <= 0:
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break
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q = table.select(whereclause=and_(*qargs), limit=qlimit,
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offset=qoffset, order_by=order_by)
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rows = list(resultiter(engine.execute(q)))
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if not len(rows):
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return
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for row in rows:
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yield row
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def distinct(engine, table, *columns):
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columns = [table.c[c] for c in columns]
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q = expression.select(columns, distinct=True)
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return list(resultiter(engine.execute(q)))
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def all(engine, table):
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return find(engine, table)
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