Django models with a many to many relationship causing conflicting ordering requirements in models.py

Question

I have issues with the two following models. The first model (QueryJob) is referenced by the second model(PropertyQuery) by a many to many field( queryID = models.ForeignKey(QueryJob,blank=True,null=True)) which necessitates that QueryJob precedes PropertyQuery.

How PropertyQuery objects are created by calling QueryJob.createqueries() which requires that PropertyQuery preceeds QueryJob.

Code is below. Is there a better way to approach this problem?

class QueryJob(models.Model):
  queryUID = models.AutoField(primary_key=True)
  client = models.ManyToManyField(Client,blank=True)
  Json = JSONField()
  street_column =models.TextField()
  state_column =models.TextField(blank=True) 
  suburb_column =models.TextField(blank=True) 
  postcode_column =models.TextField(blank=True) 
  def createqueries(self):
    #json_data = json.loads(self.Json)
    print self.Json
    for each in self.Json:
      try:
        Street = each[self.street_column]
        State = each[self.state_column]
        Suburb = each[self.suburb_column]
        Postcode = each[self.postcode_column]
        q = PropertyQuery(street_address = Street, state=State ,suburb = Suburb,postcode=Postcode,queryID=self.queryUID )
        q.save()
      except:
        pass



  def save(self, *args, **kwargs):
    self.createqueries()
    super(QueryJob, self).save(*args, **kwargs)

Second model

class PropertyQuery(models.Model):
  queryID = models.ForeignKey(QueryJob,blank=True,null=True)
  linkedproperty = models.ForeignKey(Property,blank=True,null=True)
  street_address = models.CharField(max_length=255, db_index=True,null=True)
  suburb = models.CharField(max_length=120, db_index=True,blank=True,null=True)
  state = models.CharField(max_length=3, db_index=True,blank=True,null=True)
  postcode = models.IntegerField(max_length=4, db_index=True, blank=True,null=True)
  matcheduncertainty = models.PositiveSmallIntegerField(blank=True,null=True)
  def search_for_a_match(self):
    if self.postcode:
      print self.postcode

      print Property.objects.filter(postcode=self.postcode)
      try:
        property_list = Property.objects.filter(postcode=self.postcode)

        print property_list 
      except:
        print "no properties in that postcode"
        return
    elif self.suburb:
      try:
        property_list = Property.objects.filter(suburb=self.suburb)
        print property_list 
      except:
        print "no properties in that suburb"
    elif self.state:
      try:
        property_list = Property.objects.filter(state=self.state)
        print property_list 
      except:
        print "no properties in that state"
        return
    else:
      print "no properties found"
      return
    for possible in property_list:
      if possible.street_address == self.street_address:
        self.linkedproperty = possible
        self.matcheduncertainty = 100
        return
    else:
      print "we will need to try something else"

Answer 1

Switch the order of these statements, so that your QueryJob is created first, then your PropertyQuery models are created:

def save(self, *args, **kwargs):
    super(QueryJob, self).save(*args, **kwargs)
    self.createqueries()

In your createqueries() method, you can refer to self when you need to create a link. Do not create a link to the primary key directly as this won't work - you don't realize its not working because you have a blank except clause that is catching the exceptions raised:

def createqueries(self):
    #json_data = json.loads(self.Json)
    print self.Json
    for each in self.Json:
        Street = each.get(self.street_column)
        State = each.get(self.state_column)
        Suburb = each.get(self.suburb_column)
        Postcode = each.get(self.postcode_column)
        q = PropertyQuery(street_address = Street,
                          state=State,
                          suburb = Suburb,
                          postcode=Postcode,
                          queryID=self)
        q.save()