import dbconnection
import joins
import main
import sqlbuilder
__all__ = ['SelectResults']
class SelectResults(object):
IterationClass = dbconnection.Iteration
def __init__(self, sourceClass, clause, clauseTables=None,
**ops):
self.sourceClass = sourceClass
if clause is None or isinstance(clause, str) and clause == 'all':
clause = sqlbuilder.SQLTrueClause
if not isinstance(clause, sqlbuilder.SQLExpression):
clause = sqlbuilder.SQLConstant(clause)
self.clause = clause
self.ops = ops
if ops.get('orderBy', sqlbuilder.NoDefault) is sqlbuilder.NoDefault:
ops['orderBy'] = sourceClass.sqlmeta.defaultOrder
orderBy = ops['orderBy']
if isinstance(orderBy, (tuple, list)):
orderBy = map(self._mungeOrderBy, orderBy)
else:
orderBy = self._mungeOrderBy(orderBy)
ops['dbOrderBy'] = orderBy
if 'connection' in ops and ops['connection'] is None:
del ops['connection']
if ops.get('limit', None):
assert not ops.get('start', None) and not ops.get('end', None), \
"'limit' cannot be used with 'start' or 'end'"
ops["start"] = 0
ops["end"] = ops.pop("limit")
tablesSet = sqlbuilder.tablesUsedSet(self.clause, self._getConnection().dbName)
if clauseTables:
for table in clauseTables:
tablesSet.add(table)
self.clauseTables = clauseTables
# Explicitly post-adding-in sqlmeta.table, sqlbuilder.Select will handle sqlrepr'ing and dupes
self.tables = list(tablesSet) + [sourceClass.sqlmeta.table]
def queryForSelect(self):
columns = [self.sourceClass.q.id] + [getattr(self.sourceClass.q, x.name) for x in self.sourceClass.sqlmeta.columnList]
query = sqlbuilder.Select(columns,
where=self.clause,
join=self.ops.get('join', sqlbuilder.NoDefault),
distinct=self.ops.get('distinct',False),
lazyColumns=self.ops.get('lazyColumns', False),
start=self.ops.get('start', 0),
end=self.ops.get('end', None),
orderBy=self.ops.get('dbOrderBy',sqlbuilder.NoDefault),
reversed=self.ops.get('reversed', False),
staticTables=self.tables,
forUpdate=self.ops.get('forUpdate', False))
return query
def __repr__(self):
return "<%s at %x>" % (self.__class__.__name__, id(self))
def _getConnection(self):
return self.ops.get('connection') or self.sourceClass._connection
def __str__(self):
conn = self._getConnection()
return conn.queryForSelect(self)
def _mungeOrderBy(self, orderBy):
if isinstance(orderBy, str) and orderBy.startswith('-'):
orderBy = orderBy[1:]
desc = True
else:
desc = False
if isinstance(orderBy, basestring):
if orderBy in self.sourceClass.sqlmeta.columns:
val = getattr(self.sourceClass.q, self.sourceClass.sqlmeta.columns[orderBy].name)
if desc:
return sqlbuilder.DESC(val)
else:
return val
else:
orderBy = sqlbuilder.SQLConstant(orderBy)
if desc:
return sqlbuilder.DESC(orderBy)
else:
return orderBy
else:
return orderBy
def clone(self, **newOps):
ops = self.ops.copy()
ops.update(newOps)
return self.__class__(self.sourceClass, self.clause,
self.clauseTables, **ops)
def orderBy(self, orderBy):
return self.clone(orderBy=orderBy)
def connection(self, conn):
return self.clone(connection=conn)
def limit(self, limit):
return self[:limit]
def lazyColumns(self, value):
return self.clone(lazyColumns=value)
def reversed(self):
return self.clone(reversed=not self.ops.get('reversed', False))
def distinct(self):
return self.clone(distinct=True)
def newClause(self, new_clause):
return self.__class__(self.sourceClass, new_clause,
self.clauseTables, **self.ops)
def filter(self, filter_clause):
if filter_clause is None:
# None doesn't filter anything, it's just a no-op:
return self
clause = self.clause
if isinstance(clause, basestring):
clause = sqlbuilder.SQLConstant('(%s)' % self.clause)
return self.newClause(sqlbuilder.AND(clause, filter_clause))
def __getitem__(self, value):
if isinstance(value, slice):
assert not value.step, "Slices do not support steps"
if not value.start and not value.stop:
# No need to copy, I'm immutable
return self
# Negative indexes aren't handled (and everything we
# don't handle ourselves we just create a list to
# handle)
if (value.start and value.start < 0) \
or (value.stop and value.stop < 0):
if value.start:
if value.stop:
return list(self)[value.start:value.stop]
return list(self)[value.start:]
return list(self)[:value.stop]
if value.start:
assert value.start >= 0
start = self.ops.get('start', 0) + value.start
if value.stop is not None:
assert value.stop >= 0
if value.stop < value.start:
# an empty result:
end = start
else:
end = value.stop + self.ops.get('start', 0)
if self.ops.get('end', None) is not None and \
self.ops['end'] < end:
# truncated by previous slice:
end = self.ops['end']
else:
end = self.ops.get('end', None)
else:
start = self.ops.get('start', 0)
end = value.stop + start
if self.ops.get('end', None) is not None \
and self.ops['end'] < end:
end = self.ops['end']
return self.clone(start=start, end=end)
else:
if value < 0:
return list(iter(self))[value]
else:
start = self.ops.get('start', 0) + value
return list(self.clone(start=start, end=start+1))[0]
def __iter__(self):
# @@: This could be optimized, using a simpler algorithm
# since we don't have to worry about garbage collection,
# etc., like we do with .lazyIter()
return iter(list(self.lazyIter()))
def lazyIter(self):
"""
Returns an iterator that will lazily pull rows out of the
database and return SQLObject instances
"""
conn = self._getConnection()
return conn.iterSelect(self)
def accumulate(self, *expressions):
""" Use accumulate expression(s) to select result
using another SQL select through current
connection.
Return the accumulate result
"""
conn = self._getConnection()
exprs = []
for expr in expressions:
if not isinstance(expr, sqlbuilder.SQLExpression):
expr = sqlbuilder.SQLConstant(expr)
exprs.append(expr)
return conn.accumulateSelect(self, *exprs)
def count(self):
""" Counting elements of current select results """
assert not self.ops.get('start') and not self.ops.get('end'), \
"start/end/limit have no meaning with 'count'"
assert not (self.ops.get('distinct') and (self.ops.get('start')
or self.ops.get('end'))), \
"distinct-counting of sliced objects is not supported"
if self.ops.get('distinct'):
# Column must be specified, so we are using unique ID column.
# COUNT(DISTINCT column) is supported by MySQL and PostgreSQL,
# but not by SQLite. Perhaps more portable would be subquery:
# SELECT COUNT(*) FROM (SELECT DISTINCT id FROM table)
count = self.accumulate('COUNT(DISTINCT %s)' % self._getConnection().sqlrepr(self.sourceClass.q.id))
else:
count = self.accumulate('COUNT(*)')
if self.ops.get('start'):
count -= self.ops['start']
if self.ops.get('end'):
count = min(self.ops['end'] - self.ops.get('start', 0), count)
return count
def accumulateMany(self, *attributes):
""" Making the expressions for count/sum/min/max/avg
of a given select result attributes.
`attributes` must be a list/tuple of pairs (func_name, attribute);
`attribute` can be a column name (like 'a_column')
or a dot-q attribute (like Table.q.aColumn)
"""
expressions = []
conn = self._getConnection()
if self.ops.get('distinct'):
distinct = 'DISTINCT '
else:
distinct = ''
for func_name, attribute in attributes:
if not isinstance(attribute, str):
attribute = conn.sqlrepr(attribute)
expression = '%s(%s%s)' % (func_name, distinct, attribute)
expressions.append(expression)
return self.accumulate(*expressions)
def accumulateOne(self, func_name, attribute):
""" Making the sum/min/max/avg of a given select result attribute.
`attribute` can be a column name (like 'a_column')
or a dot-q attribute (like Table.q.aColumn)
"""
return self.accumulateMany((func_name, attribute))
def sum(self, attribute):
return self.accumulateOne("SUM", attribute)
def min(self, attribute):
return self.accumulateOne("MIN", attribute)
def avg(self, attribute):
return self.accumulateOne("AVG", attribute)
def max(self, attribute):
return self.accumulateOne("MAX", attribute)
def getOne(self, default=sqlbuilder.NoDefault):
"""
If a query is expected to only return a single value,
using ``.getOne()`` will return just that value.
If not results are found, ``SQLObjectNotFound`` will be
raised, unless you pass in a default value (like
``.getOne(None)``).
If more than one result is returned,
``SQLObjectIntegrityError`` will be raised.
"""
results = list(self)
if not results:
if default is sqlbuilder.NoDefault:
raise main.SQLObjectNotFound(
"No results matched the query for %s"
% self.sourceClass.__name__)
return default
if len(results) > 1:
raise main.SQLObjectIntegrityError(
"More than one result returned from query: %s"
% results)
return results[0]
def throughTo(self):
class _throughTo_getter(object):
def __init__(self, inst):
self.sresult = inst
def __getattr__(self, attr):
return self.sresult._throughTo(attr)
return _throughTo_getter(self)
throughTo = property(throughTo)
def _throughTo(self, attr):
otherClass = None
orderBy = sqlbuilder.NoDefault
ref = self.sourceClass.sqlmeta.columns.get(attr.endswith('ID') and attr or attr+'ID', None)
if ref and ref.foreignKey:
otherClass, clause = self._throughToFK(ref)
else:
join = [x for x in self.sourceClass.sqlmeta.joins if x.joinMethodName==attr]
if join:
join = join[0]
orderBy = join.orderBy
if hasattr(join, 'otherColumn'):
otherClass, clause = self._throughToRelatedJoin(join)
else:
otherClass, clause = self._throughToMultipleJoin(join)
if not otherClass:
raise AttributeError("throughTo argument (got %s) should be name of foreignKey or SQL*Join in %s" % (attr, self.sourceClass))
return otherClass.select(clause,
orderBy=orderBy,
connection=self._getConnection())
def _throughToFK(self, col):
otherClass = getattr(self.sourceClass, "_SO_class_"+col.foreignKey)
colName = col.name
query = self.queryForSelect().newItems([sqlbuilder.ColumnAS(getattr(self.sourceClass.q, colName), colName)]).orderBy(None).distinct()
query = sqlbuilder.Alias(query, "%s_%s" % (self.sourceClass.__name__, col.name))
return otherClass, otherClass.q.id==getattr(query.q, colName)
def _throughToMultipleJoin(self, join):
otherClass = join.otherClass
colName = join.soClass.sqlmeta.style.dbColumnToPythonAttr(join.joinColumn)
query = self.queryForSelect().newItems([sqlbuilder.ColumnAS(self.sourceClass.q.id, 'id')]).orderBy(None).distinct()
query = sqlbuilder.Alias(query, "%s_%s" % (self.sourceClass.__name__, join.joinMethodName))
joinColumn = getattr(otherClass.q, colName)
return otherClass, joinColumn==query.q.id
def _throughToRelatedJoin(self, join):
otherClass = join.otherClass
intTable = sqlbuilder.Table(join.intermediateTable)
colName = join.joinColumn
query = self.queryForSelect().newItems([sqlbuilder.ColumnAS(self.sourceClass.q.id, 'id')]).orderBy(None).distinct()
query = sqlbuilder.Alias(query, "%s_%s" % (self.sourceClass.__name__, join.joinMethodName))
clause = sqlbuilder.AND(otherClass.q.id == getattr(intTable, join.otherColumn),
getattr(intTable, colName) == query.q.id)
return otherClass, clause