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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