我一直在学习使用 SQLAlchemy，并试图让它加载数据库中已经存在的数据，通过将元组添加到列表来更改对象的值，然后在数据库中保存/更新它们。
出于某种原因，当我将元组附加到作为元组列表的属性时，SQLAlchemy 的更新程序会忽略它。使用 Session.dirty 并重新查询数据库显示该值没有发生任何变化。
如何创建或更新作为元组列表的对象属性，以便也更新数据库？
这是数据库的代码：
class SQLAlchemyDatabase():
def __init__(self, DBDirectory, ThisDatabaseName, Report=False):
''' Creating the database by path and name given '''
self.Directory = DBDirectory
self.DatabaseName = ThisDatabaseName
# I can't remember why this was in my c++ code...
# if the new directory should be in another folder,
# add the backslash, otherwise keep it free of
# backslashes to make it in the current folder
if len(self.Directory) > 0:
self.Directory = self.Directory + "\\"
DatabasePath = self.Directory + self.DatabaseName
print "Opening", DatabasePath
EngineCommand = "sqlite:///"
self.engine = sqlalchemy.create_engine(EngineCommand+DatabasePath, echo=Report)
self.Session = sessionmaker(bind=self.engine)
self.Base = declarative_base()
try:
self.DB = self.Session()
except Error as e:
print "An error occurred in making the database at", DatabasePath, ":", e.args[0]
self.Base.metadata.create_all(self.engine)
Statics = SQLAlchemyDatabase("", "Tester.db", True)
这是对象的类代码：
class TestObj(Statics.Base):
""" Objects that exist as a template for all base objects """
__tablename__ = "TestObj"
ID = Column(Text, primary_key=True)
ListOfTuples = Column(PickleType, primary_key=False) # List of dual int tuples
Digit = Column(Integer, primary_key=False)
def __init__(self,ID, ListOfTuples, Digit):
# Unique Identifier
self.ID = ID
# List of paired int tuples
self.ListOfTuples = ListOfTuples
# Some other digit
self.Digit = Digit
def __repr__(self, ):
return "<Material ('%s', '%s', '%s')>" % (self.ID, self.ListOfTuples, self.Digit)
这是我添加、加载、修改然后检查数据库是否更新的代码：
print "Creating each TestObj"
TestObj1 = TestObj("M001", [], 0)
TestObj2 = TestObj("M002", [], 0)
TestObj3 = TestObj("M003", [], 0)
print "Creating the table in the DB"
Statics.Base.metadata.create_all(Statics.engine)
print "Adding each object to the table"
Statics.DB.add(TestObj1)
Statics.DB.add(TestObj2)
Statics.DB.add(TestObj3)
print "Querying the table for the objects"
ListOfObjects = Statics.DB.query(TestObj).all()
print ListOfObjects
print "Modifying the objects to test updating"
NewDigit = 1
for EachObject in ListOfObjects:
print EachObject
EachObject.ListOfTuples.append((1,2))
EachObject.Digit = NewDigit
NewDigit += 1
print "Now the Object is:", EachObject
print "Seeing what is to be updated (should show all 3 objects with the ListOfTuples attribute for changing)"
print Statics.DB.dirty
print "Commit changes to DB"
print Statics.DB.commit()
print "Re-query the database to see what the values are now"
ListOfObjects2 = Statics.DB.query(TestObj).all()
print ListOfObjects