Django talk: Re: New user - struggling with database design

Thursday, August 28, 2014

Re: New user - struggling with database design

their order if I am understanding you right does not effect this, the last part is just a join between the tables, you don't have to create another table

On Thu, Aug 28, 2014 at 8:46 AM, Jason G <jason.grazado@gmail.com> wrote:

Hi all,

I am building an app to track my home brewing.

I have two tables, one for vessels, and another for brews.

I want the Brew table to have a pick-list, relation to Vessels so I can say what vessel the brew is in.

I also want to render a table that shows all Vessels and what Brew is in each. There should be a one-to-one relationship until the Brew is 'Kicked', which could be a vessel or maybe a null value in the Brew table.

My code currently doesn't work, but looks something like this:

class Vessel(models.Model):
Name = models.CharField(max_length=20)
Gallons = models.DecimalField(max_digits=4, decimal_places=2, null=True, blank=True)

Weight = models.DecimalField(max_digits=4, decimal_places=2, null=True, blank=True)
CurrentBrew = models.ForeignKey(Brew, db_column='Vessel') <--------------------------------------this is what I'm trying to add

def __unicode__(self):
return self.Name

class Brew(models.Model):
...
Name = models.CharField(max_length=40, null=True, default='TBD')

InformalName = models.CharField(max_length=40)
Status = models.IntegerField(max_length=1, choices=STATUS_CHOICES, default=1, null=False, blank=False)
Gallons = models.DecimalField(max_digits=4, decimal_places=2, null=True, blank=True)

Vessel = models.ForeignKey(Vessel)
Style = models.ForeignKey(Style)
Event = models.CharField(max_length=40, null=True, blank=True)

In this model, which I'm not sure is the best way to do it, the Vessel class does not yet know about the Brew model that is below it.

I'm starting to grasp this language (and love it, coming from doing asp/sql several years ago) but I'm stuck here. Help!

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