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import sqlalchemy.sql as sql
import sqlalchemy.mapping as mapping
def install_plugin():
mapping.extensions.append(SelectResultsExt)
class SelectResultsExt(mapping.MapperExtension):
def select_by(self, mapper, *args, **params):
return SelectResults(mapper, mapper._by_clause(*args, **params))
def select(self, mapper, arg=None, **kwargs):
if arg is not None and isinstance(arg, sql.Selectable):
return mapping.EXT_PASS
else:
return SelectResults(mapper, arg, ops=kwargs)
class SelectResults(object):
def __init__(self, mapper, clause=None, ops={}):
self._mapper = mapper
self._clause = clause
self._ops = {}
self._ops.update(ops)
def count(self):
return self._mapper.count(self._clause)
def min(self, col):
return sql.select([sql.func.min(col)], self._clause, **self._ops).scalar()
def max(self, col):
return sql.select([sql.func.max(col)], self._clause, **self._ops).scalar()
def sum(self, col):
return sql.select([sql.func.sum(col)], self._clause, **self._ops).scalar()
def avg(self, col):
return sql.select([sql.func.avg(col)], self._clause, **self._ops).scalar()
def clone(self):
return SelectResults(self._mapper, self._clause, self._ops.copy())
def filter(self, clause):
new = self.clone()
new._clause = sql.and_(self._clause, clause)
return new
def order_by(self, order_by):
new = self.clone()
new._ops['order_by'] = order_by
return new
def limit(self, limit):
return self[:limit]
def offset(self, offset):
return self[offset:]
def list(self):
return list(self)
def __getitem__(self, item):
if isinstance(item, slice):
start = item.start
stop = item.stop
if (isinstance(start, int) and start < 0) or \
(isinstance(stop, int) and stop < 0):
return list(self)[item]
else:
res = self.clone()
if start is not None and stop is not None:
res._ops.update(dict(offset=start, limit=stop-start))
elif start is None and stop is not None:
res._ops.update(dict(limit=stop))
elif start is not None and stop is None:
res._ops.update(dict(offset=start))
if item.step is not None:
return list(res)[None:None:item.step]
else:
return res
else:
return list(self[item:item+1])[0]
def __iter__(self):
return iter(self._mapper.select_whereclause(self._clause, **self._ops))
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