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• SQLAlchemy returns tuple not dictionary

  - by Ivan

  Hi everyone, I've updated SQLAlchemy to 0.6 but it broke everything. I've noticed it returns tuple not a dictionary anymore. Here's a sample query: query = session.query(User.id, User.username, User.email).filter(and_(User.id == id, User.username == username)).limit(1) result = session.execute(query).fetchone() This piece of code used to return a dictionary in 0.5. My question is how can I return a dictionary?

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• SQLAlchemy: a better way for update with declarative?

  - by hadrien

  I am a SQLAlchemy noob. Let's say I have an user table in declarative mode: class User(Base): __tablename__ = 'user' id = Column(u'id', Integer(), primary_key=True) name = Column(u'name', String(50)) When I know user's id without object loaded into session, I update such user like this: ex = update(User.__table__).where(User.id==123).values(name=u"Bob Marley") Session.execute(ex) I dislike using User.__table__, should I stop worrying with that? Is there a better way to do this? Thanx!

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• SQLAlchemy autocommiting?

  - by muckabout

  I have an issue with SQLAlchemy apparently committing. A rough sketch of my code: trans = self.conn.begin() try: assert not self.conn.execute(my_obj.__table__.select(my_obj.id == id)).first() self.conn.execute(my_obj.__table__.insert().values(id=id)) assert not self.conn.execute(my_obj.__table__.select(my_obj.id == id)).first() except: trans.rollback() raise I don't commit, and the second assert always fails! In other words, it seems the data is getting inserted into the database even though the code is within a transaction! Is this assessment accurate?

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• working with django and sqlalchemy but backend mysql

  - by nazmul hasan

  i am working with python django framework but in model part is sqlalchemy and back end data base is mysql how i will configure them???

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• SQLAlchemy introspection

  - by Shaman

  What I am trying to do is to get from SqlAlchemy entity definition all it's Column()'s, determine their types and constraints, to be able to pre-validate, convert data and display custom forms to user. How can I introspect it? Example: class Person(Base): ''' Represents Person ''' __tablename__ = 'person' # Columns id = Column(String(8), primary_key=True, default=uid_gen) title = Column(String(512), nullable=False) birth_date = Column(DateTime, nullable=False) I want to get this id, title, birth date, determine their restrictions (such as title is string and max length is 512 or birth_date is datetime etc) Thank you

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• Batch select with SQLAlchemy

  - by muckabout

  I have a large set of values V, some of which are likely to exist in a table T. I would like to insert into the table those which are not yet inserted. So far I have the code: for value in values: s = self.conn.execute(mytable.__table__.select(mytable.value == value)).first() if not s: to_insert.append(value) I feel like this is running slower than it should. I have a few related questions: Is there a way to construct a select statement such that you provide a list (in this case, 'values') to which sqlalchemy responds with records which match that list? Is this code overly expensive in constructing select objects? Is there a way to construct a single select statement, then parameterize at execution time?

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• strange SqlAlchemy update behaviour

  - by Max

  I'm new to SqlAlchemy and Elixir, so I've started from tutorial and tried to create table, insert a record, and then update it as follows: #'elixir_test.py' from elixir import * metadata.bind = "postgresql://myuser:mypwd@localhost:5432/dbname" metadata.bind.echo = True class Movie(Entity): title = Field(Unicode(30)) year = Field(Integer) description = Field(UnicodeText) def __repr__(self): return '<Movie "%s" (%d)>' % (self.title, self.year) and in another file in the same directory: from elixir_test import * setup_all() #create table create_all() Movie(title=u"Blade Runner", year=1982) #add record session.commit() #get records Movie.query.all() #trying to update record and commit changes, BUT... movie = Movie.query.first() movie.year = 1983 session.commit() #now we have two records in our table, one #with year=1982 and one with year=1983 Movie.query.all() What did I missed?

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• Sqlalchemy+elixir: How query with a ManyToMany relationship?

  - by Hugo

  Hi, I'm using sqlalchemy with Elixir and have some troubles trying to make a query.. I have 2 entities, Customer and CustomerList, with a many to many relationship. customer_lists_customers_table = Table('customer_lists_customers', metadata, Column('id', Integer, primary_key=True), Column('customer_list_id', Integer, ForeignKey("customer_lists.id")), Column('customer_id', Integer, ForeignKey("customers.id"))) class Customer(Entity): [...] customer_lists = ManyToMany('CustomerList', table=customer_lists_customers_table) class CustomerList(Entity): [...] customers = ManyToMany('Customer', table=customer_lists_customers_table) I'm tryng to find CustomerList with some customer: customer = [...] CustomerList.query.filter_by(customers.contains(customer)).all() But I get the error: NameError: global name 'customers' is not defined customers seems to be unrelated to the entity fields, there's an special query form to work with relationships (or ManyToMany relationships)? Thanks

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• Trouble with copying dictionaries and using deepcopy on an SQLAlchemy ORM object

  - by Az

  Hi there, I'm doing a Simulated Annealing algorithm to optimise a given allocation of students and projects. This is language-agnostic pseudocode from Wikipedia: s ? s0; e ? E(s) // Initial state, energy. sbest ? s; ebest ? e // Initial "best" solution k ? 0 // Energy evaluation count. while k < kmax and e > emax // While time left & not good enough: snew ? neighbour(s) // Pick some neighbour. enew ? E(snew) // Compute its energy. if enew < ebest then // Is this a new best? sbest ? snew; ebest ? enew // Save 'new neighbour' to 'best found'. if P(e, enew, temp(k/kmax)) > random() then // Should we move to it? s ? snew; e ? enew // Yes, change state. k ? k + 1 // One more evaluation done return sbest // Return the best solution found. The following is an adaptation of the technique. My supervisor said the idea is fine in theory. First I pick up some allocation (i.e. an entire dictionary of students and their allocated projects, including the ranks for the projects) from entire set of randomised allocations, copy it and pass it to my function. Let's call this allocation aOld (it is a dictionary). aOld has a weight related to it called wOld. The weighting is described below. The function does the following: Let this allocation, aOld be the best_node From all the students, pick a random number of students and stick in a list Strip (DEALLOCATE) them of their projects ++ reflect the changes for projects (allocated parameter is now False) and lecturers (free up slots if one or more of their projects are no longer allocated) Randomise that list Try assigning (REALLOCATE) everyone in that list projects again Calculate the weight (add up ranks, rank 1 = 1, rank 2 = 2... and no project rank = 101) For this new allocation aNew, if the weight wNew is smaller than the allocation weight wOld I picked up at the beginning, then this is the best_node (as defined by the Simulated Annealing algorithm above). Apply the algorithm to aNew and continue. If wOld < wNew, then apply the algorithm to aOld again and continue. The allocations/data-points are expressed as "nodes" such that a node = (weight, allocation_dict, projects_dict, lecturers_dict) Right now, I can only perform this algorithm once, but I'll need to try for a number N (denoted by kmax in the Wikipedia snippet) and make sure I always have with me, the previous node and the best_node. So that I don't modify my original dictionaries (which I might want to reset to), I've done a shallow copy of the dictionaries. From what I've read in the docs, it seems that it only copies the references and since my dictionaries contain objects, changing the copied dictionary ends up changing the objects anyway. So I tried to use copy.deepcopy().These dictionaries refer to objects that have been mapped with SQLA. Questions: I've been given some solutions to the problems faced but due to my über green-ness with using Python, they all sound rather cryptic to me. Deepcopy isn't playing nicely with SQLA. I've been told thatdeepcopy on ORM objects probably has issues that prevent it from working as you'd expect. Apparently I'd be better off "building copy constructors, i.e. def copy(self): return FooBar(....)." Can someone please explain what that means? I checked and found out that deepcopy has issues because SQLAlchemy places extra information on your objects, i.e. an _sa_instance_state attribute, that I wouldn't want in the copy but is necessary for the object to have. I've been told: "There are ways to manually blow away the old _sa_instance_state and put a new one on the object, but the most straightforward is to make a new object with __init__() and set up the attributes that are significant, instead of doing a full deep copy." What exactly does that mean? Do I create a new, unmapped class similar to the old, mapped one? An alternate solution is that I'd have to "implement __deepcopy__() on your objects and ensure that a new _sa_instance_state is set up, there are functions in sqlalchemy.orm.attributes which can help with that." Once again this is beyond me so could someone kindly explain what it means? A more general question: given the above information are there any suggestions on how I can maintain the information/state for the best_node (which must always persist through my while loop) and the previous_node, if my actual objects (referenced by the dictionaries, therefore the nodes) are changing due to the deallocation/reallocation taking place? That is, without using copy?

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• SQLAlchemy introspection of ORM classes/objects

  - by Adam Batkin

  I am looking for a way to introspect SQLAlchemy ORM classes/entities to determine the types and other constraints (like maximum lengths) of an entity's properties. For example, if I have a declarative class: class User(Base): __tablename__ = "USER_TABLE" id = sa.Column(sa.types.Integer, primary_key=True) fullname = sa.Column(sa.types.String(100)) username = sa.Column(sa.types.String(20), nullable=False) password = sa.Column(sa.types.String(20), nullable=False) created_timestamp = sa.Column(sa.types.DateTime, nullable=False) I would want to be able to find out that the 'fullname' field should be a String with a maximum length of 100, and is nullable. And the 'created_timestamp' field is a DateTime and is not nullable.

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• SQLAlchemy declarative syntax with autoload in Pylons

  - by Juliusz Gonera

  I would like to use autoload to use an existings database. I know how to do it without declarative syntax (model/_init_.py): def init_model(engine): """Call me before using any of the tables or classes in the model""" t_events = Table('events', Base.metadata, schema='events', autoload=True, autoload_with=engine) orm.mapper(Event, t_events) Session.configure(bind=engine) class Event(object): pass This works fine, but I would like to use declarative syntax: class Event(Base): __tablename__ = 'events' __table_args__ = {'schema': 'events', 'autoload': True} Unfortunately, this way I get: sqlalchemy.exc.UnboundExecutionError: No engine is bound to this Table's MetaData. Pass an engine to the Table via autoload_with=<someengine>, or associate the MetaData with an engine via metadata.bind=<someengine> The problem here is that I don't know where to get the engine from (to use it in autoload_with) at the stage of importing the model (it's available in init_model()). I tried adding meta.Base.metadata.bind(engine) to environment.py but it doesn't work. Anyone has found some elegant solution?

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• How to discover table properties from SQLAlchemy mapped object

  - by ssaboum

  Hi, My point is i have a class mapped with a table, in my case in a declarative way, and i want to "discover" table properties, columns, names, relations, from this class : engine = create_engine('sqlite:///' + databasePath, echo=True) # setting up root class for declarative declaration Base = declarative_base(bind=engine) class Ship(Base): __tablename__ = 'ships' id = Column(Integer, primary_key=True) name = Column(String(255)) def __init__(self, name): self.name = name def __repr__(self): return "<Ship('%s')>" % (self.name) So now my goal is from the "Ship" class to get the table columns and their properties from another piece of code. I guess i can deal with it using instrumentation but is there any way provided by the SQLAlchemy API ? Thank you.

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• Filter objects within two seconds of one another using SQLAlchemy

  - by Arrieta

  Hello: I have two tables with a column 'date'. One holds (name, date) and the other holds (date, p1, p2). Given a name, I want to use the date in table 1 to query p1 and p2 from table two; the match should happen if date in table one is within two seconds of date in table two. How can you accomplish this using SQLAlchemy? I've tried (unsuccessfully) to use the between operator and with a clause like: td = datetime.timedelta(seconds=2) q = session.query(table1, table2).filter(table1.name=='my_name').\ filter(between(table1.date, table2.date - td, table2.date + td)) Any thoughts?

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• How do I do a semijoin using SQLAlchemy?

  - by Jason Baker

  http://en.wikipedia.org/wiki/Relational_algebra#Semijoin Let's say that I have two tables: A and B. I want to make a query that would work similarly to the following SQL statement using the SQLAlchemy orm: SELECT A.* FROM A, B WHERE A.id = B.id AND B.type = 'some type'; The thing is that I'm trying to separate out A and B's logic into different places. So I'd like to make two queries that I can define in separate places: one where A uses B as a subquery, but only returns rows from A. I'm sure this is fairly easy to do, but an example would be nice if someone could show me.

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• How do you get SQLAlchemy to override MySQL "on update CURRENT_TIMESTAMP"

  - by nocola

  I've inherited an older database that was setup with a "on update CURRENT_TIMESTAMP" put on a field that should only describe an item's creation. With PHP I have been using "timestamp=timestamp" on UPDATE clauses, but in SQLAlchemy I can't seem to force the system to use the set timestamp. Do I have no choice and need to update the MySQL table (millions of rows)? foo = session.query(f).get(int(1)) ts = foo.timestamp setattr(foo, 'timestamp', ts) setattr(foo, 'bar', bar) www_model.www_Session.commit() I have also tried: foo = session.query(f).get(int(1)) setattr(foo, 'timestamp', foo.timestamp) setattr(foo, 'bar', bar) www_model.www_Session.commit()

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• Clear sqlalchemy reflection cache

  - by OrganicPanda

  Hi all, I'm using sqlalchemy's reflection tools to get a Table object. I do this because these tables are dynamic and tables/columns can change. Here's the code I'm using: def getTableByReflection(self, tableName, metadata, engine): return Table(tableName, metadata, autoload = True, autoload_with = engine) The problem is that when the above code is run twice it seems to return the same results regardless of whether or not the columns have changed. I have tried refreshing using the mysession.refresh(mytable) but that fails because the table is not attached to any metadata - which makes sense but then why am I seeing cached results? Is there any way to tell the metadata/engine/session to forget about this table and let me load it cleanly?

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• Many-to-one relationship in SQLAlchemy

  - by Arrieta

  This is a beginner-level question. I have a catalog of mtypes: mtype_id name 1 'mtype1' 2 'mtype2' [etc] and a catalog of Objects, which must have an associated mtype: obj_id mtype_id name 1 1 'obj1' 2 1 'obj2' 3 2 'obj3' [etc] I am trying to do this in SQLAlchemy by creating the following schemas: mtypes_table = Table('mtypes', metadata, Column('mtype_id', Integer, primary_key=True), Column('name', String(50), nullable=False, unique=True), ) objs_table = Table('objects', metadata, Column('obj_id', Integer, primary_key=True), Column('mtype_id', None, ForeignKey('mtypes.mtype_id')), Column('name', String(50), nullable=False, unique=True), ) mapper(MType, mtypes_table) mapper(MyObject, objs_table, properties={'mtype':Relationship(MType, backref='objs', cascade="all, delete-orphan")} ) When I try to add a simple element like: mtype1 = MType('mtype1') obj1 = MyObject('obj1') obj1.mtype=mtype1 session.add(obj1) I get the error: AttributeError: 'NoneType' object has no attribute 'cascade_iterator' Any ideas?

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• SQLAlchemy - loading user by username

  - by keithjgrant

  Just diving into pylons here, and am trying to get my head around the basics of SQLALchemy. I have figured out how to load a record by id: user_q = session.query(model.User) user = user_q.get(user_id) But how do I query by a specific field (i.e. username)? I assume there is a quick way to do it with the model rather than hand-building the query. I think it has something with the add_column() function on the query object, but I can't quite figure out how to use it. I've been trying stuff like this, but obviously it doesn't work: user_q = meta.Session.query(model.User).add_column('username'=user_name) user = user_q.get()

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• Creating tables with pylons and SQLAlchemy

  - by Sid

  I'm using SQLAlchemy and I can create tables that I have defined in /model/__init__.py but I have defined my classes, tables and their mappings in other files found in the /model directory. For example I have a profile class and a profile table which are defined and mapped in /model/profile.py To create the tables I run: paster setup-app development.ini But my problem is that the tables that I have defined in /model/__init__.py are created properly but the table definitions found in /model/profile.py are not created. How can I execute the table definitions found in the /model/profile.py so that all my tables can be created? Thanks for the help!

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• How to improve the speed of a loop containing a sqlalchemy query statement as conditional

  - by LtPinback

  This loop checks if a record is in the sqlite database and builds a list of dictionaries for those records that are missing and then executes a multiple insert statement with the list. This works but it is very slow (at least i think it is slow) as it takes 5 minutes to loop over 3500 queries. I am a complete newbie in python, sqlite and sqlalchemy so I wonder if there is a faster way of doing this. list_dict = [] session = Session() for data in data_list: if session.query(Class_object).filter(Class_object.column_name_01 == data[2]).filter(Class_object.column_name_00 == an_id).count() == 0: list_dict.append({'column_name_00':a_id, 'column_name_01':data[2]}) conn = engine.connect() conn.execute(prices.insert(),list_dict) conn.close() session.close() edit: I moved session = Session() outside the loop. Did not make a difference.

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• Debugging (displaying) SQL command sent to the db by SQLAlchemy

  - by morpheous

  I have an ORM class called Person, which wraps around a person table: After setting up the connection to the db etc, I run the ff statement. people = session.query(Person).all() The person table does not contain any data (as yet), so when I print the variable people, I get an empty list. I renamed the table referred to in my ORM class People, to people_foo (which does not exist). I then run the script again. I was surprised that no exception was thrown when attempting to access a table that does not exist. I therefore have the following 2 questions: How may I setup SQLAlchemy so that it propagates db errors back to the script? How may I view (i.e. print) the SQL that is being sent to the db engine If it helps, I am using PostgreSQL as the db

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• SqlAlchemy hangs after adding record in MS SQL

  - by Patrick

  I'm running SQLAlchemy on Jython and trying to connect to a MS SQL database using jTDS with windows authentication. I can query and delete just fine but when I try to insert new values it will hang when I commit. int 'before add' session.add(newVal) print 'after add' session.commit() print 'after commit' I see the first two print statements but not the last. My CPU maxes out and I can't even query the table directly using the MS SQL Management Studio. When I kill the Jython java process I can query again but the new values haven't been added. Strangely enough I can insert values directly using an SQL command: insert_sql = "INSERT INTO my_table (my_value) VALUES ('test_value')" session.execute(insert_sql) session.commit() Any ideas what I'm doing wrong?

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• Python unittest (using SQLAlchemy) does not write/update database?

  - by Jerry

  Hi, I am puzzled at why my Python unittest runs perfectly fine without actually updating the database. I can even see the SQL statements from SQLAlchemy and step through the newly created user object's email -- ...INFO sqlalchemy.engine.base.Engine.0x...954c INSERT INTO users (user_id, user_name, email, ...) VALUES (%(user_id)s, %(user_name)s, %(email)s, ...) ...INFO sqlalchemy.engine.base.Engine.0x...954c {'user_id': u'4cfdafe3f46544e1b4ad0c7fccdbe24a', 'email': u'[email protected]', ...} > .../tests/unit_tests/test_signup.py(127)test_signup_success() -> user = user_q.filter_by(user_name='test').first() (Pdb) n ...INFO sqlalchemy.engine.base.Engine.0x...954c SELECT users.user_id AS users_user_id, ... FROM users WHERE users.user_name = %(user_name_1)s LIMIT 1 OFFSET 0 ...INFO sqlalchemy.engine.base.Engine.0x...954c {'user_name_1': 'test'} > .../tests/unit_tests/test_signup.py(128)test_signup_success() -> self.assertTrue(isinstance(user, model.User)) (Pdb) user <pweb.models.User object at 0x9c95b0c> (Pdb) user.email u'[email protected]' Yet at the same time when I login to the test database, I do not see the new record there. Is it some feature from Python/unittest/SQLAlchemy/Pyramid/PostgreSQL that I'm totally unaware of? Thanks. Jerry

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• SQLAlchemy & Complex Queries

  - by user356594

  I have to implement ACL for an existing application. So I added the a user, group and groupmembers table to the database. I defined a ManyToMany relationship between user and group via the association table groupmembers. In order to protect some ressources of the app (i..e item) I added a additional association table auth_items which should be used as an association table for the ManyToMany relationship between groups/users and the specific item. item has following columns: user_id -- user table group_id -- group table item_id -- item table at least on of user_id and group_id columns are set. So it's possible to define access for a group or for a user to a specific item. I have used the AssociationProxy to define the relationship between users/groups and items. I now want to display all items which the user has access to and I have a really hard time doing that. Following criteria are used: All items which are owned by the user should be shown (item.owner_id = user.id) All public items should be shown (item.access = public) All items which the user has access to should be shown (auth_item.user_id = user.id) All items which the group of the user has access to should be shown. The first two criteria are quite straightforward, but I have a hard time doing the 3rd one. Here is my approach: clause = and_(item.access == 'public') if user is not None: clause = or_(clause,item.owner == user,item.users.contains(user),item.groups.contains(group for group in user.groups)) The third criteria produces an error. item.groups.contains(group for group in user.groups) I am actually not sure if this is a good approach at all. What is the best approach when filtering manytomany relationships? How I can filter a manytomany relationship based on another list/relationship? Btw I am using the latest sqlalchemy (6.0) and elixir version Thanks for any insights.

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• SQLAlchemy Mapping problem

  - by asdvalkn

  Dear Everyone, I am trying to sqlalchemy to correctly map my data. Note that a unified group is basically a group of groups. (One unifiedGroup maps to many groups but each group can only map to one ug). So basically this is the definition of my unifiedGroups: CREATE TABLE `unifiedGroups` ( `ugID` INT AUTO_INCREMENT, `gID` INT NOT NULL, PRIMARY KEY(`ugID`, `gID`), KEY( `gID`) ) ENGINE=MyISAM DEFAULT CHARSET=utf8 ; Note that each row is a ugID, gID tuple. ( I do not know before hand how many gID is per ugID so this is probably the most sensible and simplest method). Definition for my UnifiedGroup class class UnifiedGroup(object): """UnifiedProduct behaves very much like a group """ def __init__(self, ugID): self.ugID=ugID #Added by mapping self.groups=False def __str__(self): return '<%s:%s>' % (self.ugID, ','.join( [g for g in self.groups])) These are my mapping tables: tb_groupsInfo = Table( 'groupsInfo', metadata, Column('gID', Integer, primary_key=True), Column('gName', String(128)), ) tb_unifiedGroups = Table( 'unifiedGroups', metadata, Column('ugID', Integer, primary_key=True), Column('gID', Integer, ForeignKey('groupsInfo.gID')), ) My mapper maps in the following manner: mapper( UnifiedGroup, tb_unifiedGroups, properties={ 'groups': relation( Group, backref='unifiedGroup') }) However, when I tried to do groupInstance.unifiedGroup, I am getting an empty list [], while groupInstance.unifiedGroup.groups returns me an error: AttributeError: 'InstrumentedList' object has no attribute 'groups' Traceback (most recent call last): File "Mapping.py", line 119, in <module> print p.group.unifiedGroup.groups AttributeError: 'InstrumentedList' object has no attribute 'groups' What is wrong?

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