any table that has more than just two foreign keys to remote tables
does not normally qualify as a "secondary" table (its only allowed for
certain edge cases which are not present here). The "Join" class
mapped to the "join_table" is the right approach. In which case, you
*definitely* don't want to be using "secondary" or "secondary_join" in
any case here. Any access from A->(Join)->B where you don't want to
"see" the Join object, you should use the associationproxy at that
point - but get the entire thing to work first without using
associationproxy, as its only a convenience extension.
On Jun 16, 5:11 pm, Matt Haggard <[EMAIL PROTECTED]> wrote:
> 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' :relation(CustomerPart, backref='questionnaires')
>
> })
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