Hello guys,
I'm building a web service to provide data to our SDK and I'm facing a
wired problem. I have created 4 different models for my needs, a base class
that is called *Unit*, two derivatives from the base class *VideoUnit*,
*QuestionUnit*, and the last class is a derivative of both *VideoUnit* and
*QuestionUnit*, that is called, with lot of fantasy, *VideoQuestionUnit*.
Everything was working fine till the point I was trying to serialize this
data to be transmitted with JSON.
I successfully gather JSON from *VideoUnit* and *QuestionUnit *(thanks to
plaes<http://stackoverflow.com/questions/7102754/jsonify-a-sqlalchemy-result-set-in-flask>)
but now I can't figure out why when I try to make the same thing with
*VideoQuestioUnit
*the program crash telling me: "*KeyError: 'questions'*"
I can imagine that there is something wrong when *VideoQuestionUnit* try to
access the "*questions"* data declared in *QuestionUnit*(also my dog get
that I know), but I don't understand what's wrong with that.
Did someone have an idea of what I'm doing wrong?
*CODE:*
class Unit(db.Model):
id = db.Column(db.Integer, unique = True, primary_key = True)
name = db.Column(db.String(128), index = True, unique = False)
type = db.Column(db.SmallInteger)
brand_id = db.Column(db.Integer, db.ForeignKey('brand.id'))
@property
def serialize(self):
print "Serialize on superclass"
pass
class VideoUnit(Unit):
uri = db.Column(db.String(256), index = False, unique = False)
@property
def serialize(self):
return {
'ID' : self.id,
'Name' : self.name,
'Link' : self.uri
}
class QuestionUnit(Unit):
questions = db.relationship('Question', backref = 'QuestionUnit', lazy
= 'dynamic')
@property
def serialize(self):
return {
'ID' : self.id,
'Name' : self.name,
'Questions' : self.serialize_questions
}
@property
def serialize_questions(self):
return [item.serialize for item in self.questions]
class VideoQuestionUnit(VideoUnit, QuestionUnit):
@property
def serialize(self):
return {
'ID' : self.id,
'Name' : self.name,
'Link' : self.uri,
'Questions' : self.serialize_questions
}
@property
def serialize_questions(self):
return [item.serialize for item in self.questions]
Thanks in advance,
Enrico
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