I've got a triple join table (joining three things together) and I'm really struggling to get it to work as I intend. I've pasted the full model at the bottom. I've struggled with this off and on for months now... I don't really understand how I can get SQLAlchemy to do what I want.
The join table has 4 columns: type_id | section_id | question_id | ord What I'd like is the following: Questionnaire object with: .sections list that contain .questions list that contain: .answer So, something like: q = Questionnaire() print q.sections[2].questions[1].answer # yield the answer to question 1 of section 2 (or question 2 of section 3 depending on your indexing :) ) I encounter a problem because a Question object doesn't know what the type_id is because that is stored with the Questionnaire object. Likewise from a section object. I'm pulling my hair out... Thanks, Matt Haggard -------------------------------------------- from sqlalchemy import Column, MetaData, Table, types, ForeignKey, func from sqlalchemy.orm import mapper, relation from sqlalchemy.sql.expression import select from sqlalchemy.ext.associationproxy import association_proxy from datetime import datetime from formencode import validators from smmodels import NoHTML, SuperDateValidator metadata = MetaData() types_table = Table('q_type', metadata, Column('id', types.Integer, primary_key=True, index=True), Column('name', types.Unicode), Column('longname', types.Unicode), Column('validation_type', types.Unicode) ) customer_table_part = Table('customer', metadata, Column('id', types.Integer, primary_key=True, index=True), Column('email', types.Unicode, unique=True, index=True), Column('validation_type', types.Unicode) ) questionnaire_table = Table('q_questionnaire', metadata, Column('id', types.Integer, primary_key=True, index=True), Column('type_id', types.Integer, ForeignKey('q_type.id')), Column('started', types.DateTime, default=datetime.now), Column('firstpage_firstdone', types.DateTime), Column('firstpassed', types.DateTime), Column('customer_id', types.Integer, ForeignKey('customer.id'), index=True), Column('q_busdescrip', types.Unicode), Column('q_dsedescrip', types.Unicode), Column('q_providedallip', types.Unicode), Column('q_company_name', types.Unicode), Column('q_dba', types.Unicode), Column('q_contact_name', types.Unicode), Column('q_phone', types.Unicode), Column('q_trans_num_yearly', types.Unicode), Column('q_title', types.Unicode), Column('grade', types.Unicode), Column('failing_sections', types.Integer, default=0), Column('incomplete_sections', types.Integer, default=0), Column('number_blacklisted', types.Integer, default=0), Column('lastupdated', types.DateTime, default=datetime.now), Column('expiration_date', types.DateTime) ) questions_table = Table('q_questions_new', metadata, Column('id', types.Integer, primary_key=True, index=True), Column('display_number', types.Unicode), Column('question', types.Unicode), Column('type', types.Unicode), Column('weight', types.Integer), Column('correct_answer', types.Unicode, default=''), Column('dft_order', types.Integer) ) sections_table = Table('q_sections_new', metadata, Column('id', types.Integer, primary_key=True, index=True), Column('secnum', types.Unicode), Column('name', types.Unicode), Column('longname', types.Unicode) ) join_table = Table('q_join', metadata, Column('type_id', types.Integer, ForeignKey('q_type.id'), index=True, primary_key=True), Column('question_id', types.Integer, ForeignKey('q_questions_new.id'), index=True, primary_key=True), Column('section_id', types.Integer, ForeignKey('q_sections_new.id'), index=True, primary_key=True), Column('ord', types.Integer) ) answers_table = Table('q_answers_new', metadata, Column('id', types.Integer, primary_key=True, index=True), Column('question_id', types.Integer, ForeignKey('q_questions_new.id'), index=True), Column('q_id', types.Integer, ForeignKey('q_questionnaire.id'), index=True), Column('answer', types.Unicode), Column('answerdate', types.DateTime, default=datetime.now), Column('markedby', types.Unicode, default='hand'), Column('visible', types.Boolean, default=True) ) class qType: allquestions = association_proxy('joinObj', 'questions') sections = association_proxy('joinObj', 'sections') def __init__(self): pass def __str__(self): return 'id: %s name: %s' % (self.id, self.name) def __repr__(self): return "<Questionnaire Type(%s, name:'%s')>" % (self.id, self.name) class qJoin: def __init__(self, type_obj=None, question_obj=None, section_obj=None): self.type = type_obj self.question = question_obj self.section = section_obj def __repr__(self): return '<qJoin type,question,section:(%s,%s,%s)>' % (self.type_id, self.question_id, self.section_id) class Questionnaire: def __str__(self): return 'id: %s customer_id: %s' % (self.id, self.customer_id) def __repr__(self): return "<Questionnaire(%s, customer_id:%s)>" % (self.id, self.customer_id) question_types = ['yn','yn_na','label','comment'] class Question: #section = association_proxy('joinObj', 'section') class Section: def __init__(self): pass def getQuestions(self, type_id): '''Query for questions belonging to both this section and type_id''' q = select([join_table.c.question_id, join_table.c.ord], whereclause=[join_table.c.type_id==type_id,join_table.c.section_id==self.id]) return q class Answer: def __init__(self): pass class CustomerPart: def __init__(self): pass sections_by_type = select( [join_table.c.type_id, join_table.c.section_id], group_by=[join_table.c.section_id, join_table.c.type_id]).alias('sections_by_type') questions_sections_by_tyoe = select( [join_table.c.type_id, join_table.c.question_id, join_table.c.section_id], group_by=[join_table.c.question_id, join_table.c.section_id, join_table.c.type_id]).alias('q_s_by_type') mapper(Question, questions_table) mapper(Section, sections_table, properties={ 'questions' :relation(Question, secondary=join_table, primaryjoin = sections_table.c.id == join_table.c.section_id, secondaryjoin = join_table.c.question_id == questions_table.c.id, backref='section', order_by=join_table.c.ord), }) mapper(CustomerPart, customer_table_part) mapper(Answer, answers_table, properties={ 'question' :relation(Question, backref='answer', uselist=False) }) mapper(Join, join_table, properties={ 'type' :relation(qType), 'sections' :relation(Section, backref='parent'), 'questions' :relation(Question, backref='parent'), }) mapper(qType, types_table, order_by=types_table.c.id, properties={ 'joinObj' :relation(qJoin), 'my_sections' :relation(Section, secondary=sections_by_type, primaryjoin = types_table.c.id == sections_by_type.c.type_id, backref='type', order_by=sections_table.c.secnum), }) mapper(Questionnaire, questionnaire_table, properties={ 'answers' :relation(Answer, backref='questionnaire'), 'type' :relation(qType), 'customer' 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