Move projection queries snippets to github

Author: Jerjou Cheng

appengine/ndb/projection_queries/README.md

@@ -0,0 +1,11 @@
+## App Engine Datastore NDB Projection Queries Samples
+
+This contains snippets used in the NDB projection queries documentation,
+demonstrating various ways to make ndb projection queries.
+
+<!-- auto-doc-link -->
+These samples are used on the following documentation page:
+
+> https://cloud.google.com/appengine/docs/python/ndb/projectionqueries
+
+<!-- end-auto-doc-link -->

appengine/ndb/projection_queries/snippets.py

@@ -0,0 +1,61 @@
+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from google.appengine.ext import ndb
+
+
+class Article(ndb.Model):
+    title = ndb.StringProperty()
+    author = ndb.StringProperty()
+    tags = ndb.StringProperty(repeated=True)
+
+
+def print_author_tags():
+    query = Article.query()
+    articles = query.fetch(20, projection=[Article.author, Article.tags])
+    for article in articles:
+        print(article.author)
+        print(article.tags)
+        # article.title will raise a ndb.UnprojectedPropertyError
+
+
+class Address(ndb.Model):
+    type = ndb.StringProperty()  # E.g., 'home', 'work'
+    street = ndb.StringProperty()
+    city = ndb.StringProperty()
+
+
+class Contact(ndb.Model):
+    name = ndb.StringProperty()
+    addresses = ndb.StructuredProperty(Address, repeated=True)
+
+
+def fetch_sub_properties():
+    Contact.query().fetch(projection=["name", "addresses.city"])
+    Contact.query().fetch(projection=[Contact.name, Contact.addresses.city])
+
+
+def demonstrate_ndb_grouping():
+    Article.query(projection=[Article.author], group_by=[Article.author])
+    Article.query(projection=[Article.author], distinct=True)
+
+
+class Foo(ndb.Model):
+    A = ndb.IntegerProperty(repeated=True)
+    B = ndb.StringProperty(repeated=True)
+
+
+def declare_multiple_valued_property():
+    entity = Foo(A=[1, 1, 2, 3], B=['x', 'y', 'x'])
+    return entity

appengine/ndb/projection_queries/snippets_test.py

@@ -0,0 +1,46 @@
+# Copyright 2016 Google Inc. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import snippets
+
+
+def test_print_author_tags(testbed, capsys):
+    snippets.Article(title="one", author="Two", tags=["three"]).put()
+
+    snippets.print_author_tags()
+
+    stdout, _ = capsys.readouterr()
+    assert 'Two' in stdout
+    assert 'three' in stdout
+    assert 'one' not in stdout
+
+
+def test_fetch_sub_properties(testbed):
+    address = snippets.Address(type="home", street="college", city="staten")
+    address.put()
+    address2 = snippets.Address(type="home", street="brighton", city="staten")
+    address2.put()
+    snippets.Contact(name="one", addresses=[address, address2]).put()
+
+    snippets.fetch_sub_properties()
+
+
+def test_demonstrate_ndb_grouping(testbed):
+    snippets.Article(title="one", author="Two", tags=["three"]).put()
+
+    snippets.demonstrate_ndb_grouping()
+
+
+def test_declare_multiple_valued_property(testbed):
+    snippets.declare_multiple_valued_property()