Re: Help with defining Models for ManyToMany and OneToMany relationships...

As an update to this...  I decided to simplify things a bit.  For my contacts application, 

I decided to start with just one table.  I got that working in a Ubuntu Vbox 

environment, inside a virtualenv. 

I'm not sure if it is ok to use python manage.py makemigrations on the 

production server or if one should just do that locally and then import it.

Thanks for any advice,

This should be part of a larger posting on workflows moving from development to

production.

Thanks,

Bruce

On Saturday, April 23, 2016 at 10:30:45 AM UTC-4, Bruce Whealton wrote:

Hello all,

          So, I setup django in a virtualenv on my Ubuntu environment.  I was reading the docs and thought I had things right 

for creating the 3 models I wanted with this application. I am using Postgresql.  I have the Postgresql driver for Python/Django installed

in the virtualenv.  It is a "Contacts" app.  

First question: Do django model fields default to required unless you use blank=True, null=True?

Many of my fields, I want to have optional.

I have a class called Contact, a class called Organization and a class called Connection.  

I wanted to use the Organization as a foreign key on the Contact model.  I could have more than one contact from

an Organization.  The Connection model is inspired by the Google Plus idea of "Circles" - e.g. friends,

family, following, etc.   So, this would be a many-to-many relationship.  

My problems are (1) I cannot create connections without specifying a contact.  

(2) If I was adding a contact using the admin interface, how do I allow no value for that foreign field

or allow for some kind of ajax type of text completion?  If a person is family or friend, I may not need

to list an Organization for them.

(3) I would like to support multiple connection types - e.g. following, employer, etc.

So, here is my apps models.py file:

>>>>

from django.db import models

class Contact(models.Model):

    name = models.CharField(max_length=40)

    Organization = models.CharField(max_length=50)

    street_line1 = models.CharField("Street Line 1", max_length=50)

    street_line2 = models.CharField("Street Line 2", max_length=50)

    city = models.CharField(max_length=40)

    state = models.CharField(max_length=40)

    zipcode = models.CharField(max_length=20, blank=True, null=True)

    phone1 = models.CharField(max_length=20)

    phone2 = models.CharField(max_length=20)

    email = models.EmailField(max_length=60)

class Organization(models.Model):

    name = models.CharField(max_length=60)

    street_line1 = models.CharField("Street Line 1", max_length=50)

    street_line2 = models.CharField("Street Line 2", max_length=50)

    city = models.CharField(max_length=40)

    state = models.CharField(max_length=40)

    zipcode = models.CharField(max_length=20, blank=True, null=True,)

    phone = models.CharField(max_length=20)

    email = models.EmailField(max_length=60)

    website = models.URLField(max_length=90)

    contact_name = models.ForeignKey(Contact, on_delete=models.CASCADE)

class Connection(models.Model):

    type = models.CharField(max_length=60)

    contact_name = models.ManyToManyField(Contact)   

>>>

Thanks in advance for any suggestions,

Bruce 

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