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我有ndb模式其中有字符串重复属性。我试图检索所有具有空值的实体。但NDB查询返回空。NDB查询空字符串重复StringProperty
class A(ndb.model):
name = ndb.StringProperty()
values = ndb.StringProperty(repeated=True)
a1 = A()
a1.name = "T1"
a1.values = ['V1', 'V2']
a1.put()
a2 = A()
a2.name = "T2"
a2.values = []
a2.put()
result = A.query(A.values=="") # Return empty
result = A.query(A.values==[]) # BadValueError: Expected string, got []
for each in result:
print each.name
如何查询具有空/无值的实体?