How do I prevent a ManyToManyField('self') from linked an object to itself?

Posted by dyve on Stack Overflow See other posts from Stack Overflow or by dyve
Published on 2011-01-10T07:53:12Z Indexed on 2011/01/10 8:53 UTC
Read the original article Hit count: 341

Filed under:

django

|

django-models

Consider this model (simplified for this question):

class SecretAgentName(models.Model):
    name = models.CharField(max_length=100)
    aliases = ManyToManyField('self')

I have three names, "James Bond", "007" and "Jason Bourne". "James Bond" and "007" are aliases of each other.

This works exactly like I want it to, except for the fact that every instance can also be an alias of itself. This I want to prevent. So, there can be many SecretAgentNames, all can be aliases of each other as long as "James Bond" does not show up as an alias for "James Bond".

Can I prevent this in the model definition? If not, can I prevent it anywhere else, preferably so that the Django Admin understands it?

© Stack Overflow or respective owner

Related posts about django

Overriding the save() method of a model that uses django-mptt

as seen on Stack Overflow - Search for 'Stack Overflow'
I've been using django-mptt in my project for a while now, it's fabulous. Recently, I've found a need to override a model's save() method that uses mptt, and I'm getting an error when I try to save a new instance of that model: Exception Type: ValueError at /admin/scrivener/page/add/ Exception Value:… >>> More
Where is meta.local_fields set in django.db.models.base.py ?

as seen on Stack Overflow - Search for 'Stack Overflow'
I'm getting the error: Exception Value: (1110, "Column 'about' specified twice") As I was reviewing the Django error page, I noticed that the customizations the model User, seem to be appended to the List twice. This seems to be happening here in django/db/model/base.py in base_save(): values… >>> More
Deploying Django on EC2 using Bitnami Djangostack: WSGI script cannot be loadded

as seen on Stack Overflow - Search for 'Stack Overflow'
I've been struggling to deploy Django application on Amazon EC2 using Bitnami Djangostack for the last couple of days. When I go to http://dewey.io I see the default bitnami page (/opt/bitnami/apache2/htdocs/index.html), however, when I open http://dewey.io/portnoy, I get 'Internal Server Error'… >>> More
Internal Server Error with mod_wsgi [django] on windows xp

as seen on Stack Overflow - Search for 'Stack Overflow'
when i run development server it works very well, even an empty project runing in mod_wsgi i have no problem but when i want to put my own project i get an Internal Server Error (500) in my apache conf i put WSGIScriptAlias /codevents C:/django/apache/CODEvents.wsgi <Directory "C:/django/apache"> Order… >>> More
Internal Server Error with mod_wgsi [django] on windows xp

as seen on Stack Overflow - Search for 'Stack Overflow'
when i run development server it works very well, even an empty project runing in mod_wsgi i have no problem but when i want to put my own project i get an Internal Server Error (500) in my apache conf i put WSGIScriptAlias /codevents C:/django/apache/CODEvents.wsgi <Directory "C:/django/apache"> Order… >>> More

Related posts about django-models

how to import csv data into django models

as seen on Stack Overflow - Search for 'Stack Overflow'
i have some csv data and i want to export into django models the example of csv data 1;"02-01-101101";"Worm Gear HRF 50";"Ratio 1 : 10";"input shaft, output shaft, direction A, color dark green"; 2;"02-01-101102";"Worm Gear HRF 50";"Ratio 1 : 20";"input shaft, output shaft, direction A, color dark… >>> More
Subclassed django models with integrated querysets

as seen on Stack Overflow - Search for 'Stack Overflow'
Like in this question, except I want to be able to have querysets that return a mixed body of objects: >>> Product.objects.all() [<SimpleProduct: ...>, <OtherProduct: ...>, <BlueProduct: ...>, ...] I figured out that I can't just set Product.Meta.abstract to true or otherwise… >>> More
List display names from django models

as seen on Stack Overflow - Search for 'Stack Overflow'
I have an object: POP_CULTURE_TYPES = ( ('SG','Song'), ('MV', 'Movie'), ('GM', 'Game'), ('TV', 'TV'), ) class Pop_Culture(models.Model): name = models.CharField(max_length=30, unique=True) type = models.CharField(max_length=2, choices = POP_CULTURE_TYPES, blank=True,… >>> More
Best way to re-use the same django models and admin for multiple apps

as seen on Stack Overflow - Search for 'Stack Overflow'
Given a reference app ( called guide), how can I create additional apps that will reuse the same model/admin/views than guide - the motivation behind is to be able to individually control each subapp. guide guideApp1 exact same models/admin/views than guide guideApp2 exact same models/admin/views… >>> More
Generate unique hashes for django models

as seen on Stack Overflow - Search for 'Stack Overflow'
I want to use unique hashes for each model rather than ids. I implemented the following function to use it across the board easily. import random,hashlib from base64 import urlsafe_b64encode def set_unique_random_value(model_object,field_name='hash_uuid',length=5,use_sha=True,urlencode=False): … >>> More