我已经建立了一个CRUD API用于与database. table的Retrieve（或 Read）目前正在给我问题。关于设计的背景：还有一个从主文件（object.py）继承的便利文件，用于接受值。functionclassassessment_resultsAPIstring
它需要做什么：检查一个ID和/或检查两个参数（如果 ID 未在使用中）。如果合适的话，将其连同其详细信息一起检索。在Python 上的文档之后，我介绍了*允许可选位置参数的参数。我也从这个很棒的教程中得到了帮助。（我是设计和构建数据库以及使用 python 的新手。）
我相信检索方法正在工作，但设计或方法中一定存在缺陷，create_category_rating(...)因为Traceback现在返回的是ValueError. 我在Stacks (a similar issue)上读到我可能需要为 args 分配一个值，但似乎我是通过 API 来的。
代码如下：
对象.py
（retrieve 方法和 create_category_rating 方法）：
def retrieve_assessment_results(self, something_unique, *args):
if isinstance(something_unique, int):
return self.session.query(Assessment_Results).\
filter(Assessment_Results.id == something_unique).one()
elif isinstance(something_unique, basestring) and isinstance(args, basestring):
return self.session.query(Assessment_Results).\
filter(Assessment_Results.owner == something_unique).\
filter(Assessment_Results.assessment == args).one()
elif isinstance(something_unique, Assessment_Results) and isinstance(args, Assessment_Results):
return something_unique, args
else:
raise ValueError('Value being passed is an object')
def create_category_rating(self, category_rating_int, category, assessment_results):
new_catrating = Category_Rating(category_rating_int, category, assessment_results)
self.session.add(new_catrating)
print(new_catrating)
self.session.commit()
return(new_catrating)
便利.py （继承自object.py）
def create_category_rating(self, category_rating_int, category_name, username, name):
category = self.retrieve_category(category_name)
owner = self.retrieve_user(username)
assessment = self.retrieve_assessment(name)
assessment_results = self.retrieve_assessment_results(owner, assessment)
return super(ConvenienceAPI, self).create_category_rating(category_rating_int, category, assessment_results)
测试.py
api = ConvenienceAPI()
api.create_category_rating(2, 'Decision-Making', 'baseball', 'Becoming a Leader')
当前问题：StatementError 根据建议，更改了条件（需要解压缩并分配 *args 给出的元组）。
新 API：
def retrieve_assessment_results(self, *args):
id, assessment, owner = None, None, None
if len(args) == 1:
id, = args[0]
elif len(args) == 2:
assessment, owner = args
else:
raise ValueError('Value being passed is an object')
if id is not None:
return self.session.query(Assessment_Results).\
filter(Assessment_Results.id == id).one()
elif assessment is not None:
return self.session.query(Assessment_Results).\
filter(Assessment_Results.assessment == assessment).one()
elif owner is not None:
return self.session.query(Assessment_Results).\
filter(Assessment_Results.owner == owner).one()
追溯：
Traceback (most recent call last):
File "/usr/local/lib/python2.7/site-packages/nose/case.py", line 197, in runTest
self.test(*self.arg)
File "/Users/ack/code/venv/NotssDB/notssdb/test/test.py", line 111, in test1
api.create_category_rating(2, 'Decision-Making', 'baseball', 'Becoming a Leader')
File "/Users/ack/code/venv/NotssDB/notssdb/api/convenience.py", line 41, in create_category_rating
assessment_results = self.retrieve_assessment_results(owner, assessment)
File "/Users/ack/code/venv/NotssDB/notssdb/api/object.py", line 323, in retrieve_assessment_results
filter(Assessment_Results.assessment == assessment).one()
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2472, in one
ret = list(self)
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2515, in __iter__
return self._execute_and_instances(context)
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/query.py", line 2530, in _execute_and_instances
result = conn.execute(querycontext.statement, self._params)
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 914, in execute
return meth(self, multiparams, params)
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/sql/elements.py", line 323, in _execute_on_connection
return connection._execute_clauseelement(self, multiparams, params)
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1010, in _execute_clauseelement
compiled_sql, distilled_params
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1078, in _execute_context
None, None)
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1339, in _handle_dbapi_exception
exc_info
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
reraise(type(exception), exception, tb=exc_tb)
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/base.py", line 1073, in _execute_context
context = constructor(dialect, self, conn, *args)
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/engine/default.py", line 544, in _init_compiled
grp, m in enumerate(parameters)]
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/sql/compiler.py", line 498, in construct_params
pd[self.bind_names[bindparam]] = bindparam.effective_value
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/sql/elements.py", line 1162, in effective_value
return self.callable()
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/relationships.py", line 1386, in _go
value = fn(*arg, **kw)
File "/usr/local/lib/python2.7/site-packages/sqlalchemy/orm/mapper.py", line 2422, in _get_state_attr_by_column
return state.manager[prop.key].impl.get(state, dict_, passive=passive)
StatementError: (exceptions.KeyError) 'assessment_id' [SQL: u'SELECT assessment_results.id AS assessment_results_id, assessment_results.created_on AS assessment_results_created_on, assessment_results.owner_id AS assessment_results_owner_id, assessment_results.assessment_id AS assessment_results_assessment_id \nFROM assessment_results \nWHERE ? = assessment_results.assessment_id'] [parameters: [immutabledict({})]]