Hello,
I am using SQLAlchemy-0.7.1 and i am facing "Deferred loader for attribute"
Error while trying to access the table columns in my code.
I have table with huge number of columns around 200 fields and i have
defined the schema and entity with hybrid declarative_base approach as
below.
I have some sample testcases to assert newly inserted values in db with
normal python assert statements. When i run my sample test cases i am
getting
following error:
KeyError: "Deferred loader for attribute 'is_updated' failed to populate
correctly"
Below is my code example due to large number of columns i have not defined
entire db Table definition here.
test_table = Table("test_table", metadata,
Column('test_table_idn', Integer, primary_key=True),
Column('test_parent_table_idn', Float, ForeignKey('parent_table_idn')),
Column('name', String(10)),
Column('is_exported', Integer),
.
.
. #Other columns go here.
. #Other columns go here.
. #Other columns go here.
.
.
.
Column('is_updated', Integer)
)
class TestTable(Base):
"""
"""
___table___ = test_table
def set_all_other_attribs(self, **kwargs):
#Common method to set other column attributes.
for key, value in kwargs:
self.key = value
class TestTableInserts(TestCase):
def setUp():
"""
"""
self.session = will get session object
def test_run(self):
tbl_obj = TestTable()
dict_to_set(name='test',is_exported=1,.........is_updated=1)
tbl_obj.set_all_other_attribs(dict_to_set)
self.session.add(tbl_obj)
self.session.commit()
#Now trying to assert the records in test_table
result = self.session.query(TestTable).filter(name ==
'test').first()
assert result.name == 'test'
assert result. <http://result.name/>user_access == 1
assert result. <http://result.name/>web_addr == 'www.myweb.org'
assert result.is_updated == 1
#When i tryied to assert the above is_updated column i am getting
#KeyError: "Deferred loader for attribute 'is_updated' failed to
populate correctly
def tearDown(self):
self.session.execute('delete from test_table')
self.session.close()
File "/var/dev/SA/SampleTest/test_sample/test_insert.py", line 79, in
test_run
>>> assert result.is_updated == 1
File
"/var/dev/SA/SampleTest/eggs/SQLAlchemy-0.7.1-py2.6-linux-i686.egg/sqlalchemy/orm/attributes.py",
line 170, in __get__
return self.impl.get(instance_state(instance),dict_)
File
"/var/dev/SA/SampleTest/eggs/SQLAlchemy-0.7.1-py2.6-linux-i686.egg/sqlalchemy/orm/attributes.py",
line 439, in get
"correctly" % key)
KeyError: "Deferred loader for attribute 'is_updated' failed to populate
correctly"
Please suggest to me fix this error.
Just a thought is this error is raised for following reasons.
1. If table column name length is more than 30 chars.
2. If table has large number of columns defined.
Thanks,
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