openstack/deb-python-sqlalchemy-utils
Code Issues Proposed changes

Add chained method call API for QueryChain

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This commit is contained in:
Konsta Vesterinen
2014-05-07 09:39:19 +03:00
parent 472074d87a
commit 64a31b4478
2 changed files with 33 additions and 20 deletions
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32
sqlalchemy_utils/query_chain.py
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@@ -55,10 +55,18 @@ database.
list(chain) # all blog posts but not articles and news items list(chain) # all blog posts but not articles and news items
chain.offset = 4 chain = chain.offset(4)
list(chain) # last blog post, and first four articles list(chain) # last blog post, and first four articles
Just like with original query object the limit and offset can be chained to
return a new QueryChain.
::
chain = chain.limit(5).offset(7)
Chain slicing Chain slicing
^^^^^^^^^^^^^ ^^^^^^^^^^^^^
@@ -91,18 +99,18 @@ class QueryChain(object):
""" """
def __init__(self, queries, limit=None, offset=None): def __init__(self, queries, limit=None, offset=None):
self.queries = queries self.queries = queries
self.limit = limit self._limit = limit
self.offset = offset self._offset = offset
def __iter__(self): def __iter__(self):
consumed = 0 consumed = 0
skipped = 0 skipped = 0
for query in self.queries: for query in self.queries:
query_copy = copy(query) query_copy = copy(query)
if self.limit: if self._limit:
query = query.limit(self.limit - consumed) query = query.limit(self._limit - consumed)
if self.offset: if self._offset:
query = query.offset(self.offset - skipped) query = query.offset(self._offset - skipped)
obj_count = 0 obj_count = 0
for obj in query: for obj in query:
@@ -115,12 +123,18 @@ class QueryChain(object):
else: else:
skipped += obj_count skipped += obj_count
def limit(self, value):
return self[:value]
def offset(self, value):
return self[value:]
def __getitem__(self, key): def __getitem__(self, key):
if isinstance(key, slice): if isinstance(key, slice):
return self.__class__( return self.__class__(
queries=self.queries, queries=self.queries,
limit=key.stop, limit=key.stop if key.stop is not None else self._limit,
offset=key.start offset=key.start if key.start is not None else self._offset
) )
else: else:
for obj in self[key:1]: for obj in self[key:1]:

21
tests/test_query_chain.py
View File

@@ -57,25 +57,24 @@ class TestQueryChain(TestCase):
assert len(list(self.chain)) == 9 assert len(list(self.chain)) == 9
def test_iter_with_limit(self): def test_iter_with_limit(self):
self.chain.limit = 4 chain = self.chain.limit(4)
objects = list(self.chain) objects = list(chain)
assert self.users == objects[0:2] assert self.users == objects[0:2]
assert self.articles[0:2] == objects[2:] assert self.articles[0:2] == objects[2:]
def test_iter_with_offset(self): def test_iter_with_offset(self):
self.chain.offset = 3 chain = self.chain.offset(3)
objects = list(self.chain) objects = list(chain)
assert self.articles[1:] + self.posts == objects assert self.articles[1:] + self.posts == objects
def test_iter_with_limit_and_offset(self): def test_iter_with_limit_and_offset(self):
self.chain.offset = 3 chain = self.chain.offset(3).limit(4)
self.chain.limit = 4 objects = list(chain)
objects = list(self.chain)
assert self.articles[1:] + self.posts[0:1] == objects assert self.articles[1:] + self.posts[0:1] == objects
def test_iter_with_offset_spanning_multiple_queries(self): def test_iter_with_offset_spanning_multiple_queries(self):
self.chain.offset = 7 chain = self.chain.offset(7)
objects = list(self.chain) objects = list(chain)
assert self.posts[1:] == objects assert self.posts[1:] == objects
def test_repr(self): def test_repr(self):
@@ -83,8 +82,8 @@ class TestQueryChain(TestCase):
def test_getitem_with_slice(self): def test_getitem_with_slice(self):
chain = self.chain[1:] chain = self.chain[1:]
assert chain.offset == 1 assert chain._offset == 1
assert chain.limit is None assert chain._limit is None
def test_getitem_with_single_key(self): def test_getitem_with_single_key(self):
article = self.chain[2] article = self.chain[2]