django-orm

I have made a model change from standard = models.ManyToManyField(Standard) to standard = models.ManyToManyField(Standard, blank=True, null=True) South schemamigration for this app doesn't recognize the change? Similar to this question, which is unanswered: South migrations and changes to many-to-may fields That behavior is correct: null doesn't mean anything at the database level when used with a ManyToManyField . The declaration of a ManyToManyField causes the creation of an intermediate table to hold the relationship, and although Django will create a standard attribute on your model

I am new to Django and didn't find any reference regarding this issue. I am getting this error when i use many to many field in django model(models.py). i guess the issue is assining m2m filed in view(views.py) from form(forms.py). How to assign m2m field in view. Django version 2.O python 3.5 models.py class User(AbstractUser): username=models.CharField(max_length=20) email = models.EmailField(_('email address'), unique=True) class Setupuser(models.Model): organization=models.CharField(max_length=200,blank=False,null=True) emails_for_help = models.ManyToManyField(User) views.py class Set_user

Does select_related work for GenericRelation relations, or is there a reasonable alternative? At the moment Django's doing individual sql calls for each item in my queryset, and I'd like to avoid that using something like select_related. class Claim(models.Model): proof = generic.GenericRelation(Proof) class Proof(models.Model): content_type = models.ForeignKey(ContentType) object_id = models.PositiveIntegerField() content_object = generic.GenericForeignKey('content_type', 'object_id') I'm selecting a bunch of Claims, and I'd like the related Proofs to be pulled in instead of queried

My Models: class End_User(models.Model): location = models.ForeignKey(Location) first_name = models.CharField(max_length=70, blank=True, null=True) email_address = models.CharField(max_length=70, blank=True, null=True) class Phone_Client(models.Model): end_user = models.ManyToManyField(End_User) ... extensions = models.CharField(max_length=20) class Line(models.Model): phone_client = models.ManyToManyField(Phone_Client, through='Phone_Line' ) .... voicemail = models.BooleanField(default=False) class Phone_Line(models.Model): phone_client = models.ForeignKey(Phone_Client) line = models

In my model, I want a field that has a list of triplets. e.g. [[1, 3, 4], [4, 2, 6], [8, 12, 3], [3, 3, 9]] . Is there a field that can store this data in the database? You can convert it into string by using JSON and store it as string. For example, In [3]: json.dumps([[1, 3, 4], [4, 2, 6], [8, 12, 3], [3, 3, 9]]) Out[3]: '[[1, 3, 4], [4, 2, 6], [8, 12, 3], [3, 3, 9]]' You can add a method into your class to convert it automatically for you. import json class Foobar(models.Model): foo = models.CharField(max_length=200) def set_foo(self, x): self.foo = json.dumps(x) def get_foo(self): return

I know Django does not support foreign keys across multiple databases (originally Django 1.3 docs) But I'm looking for a workaround. What doesn't work I have two models each on a separate database. routers.py: class NewsRouter(object): def db_for_read(self, model, **hints): if model._meta.app_label == 'news_app': return 'news_db' return None def db_for_write(self, model, **hints): if model._meta.app_label == 'news_app': return 'news_db' return None def allow_relation(self, obj1, obj2, **hints): if obj1._meta.app_label == 'news_app' or obj2._meta.app_label == 'news_app': return True return None

With the following models: class OrderOperation(models.Model): ordered_articles = models.ManyToManyField(Article, through='orders.OrderedArticle') class OrderedArticle(models.Model): order_operation = models.ForeignKey(OrderOperation) article = models.ForeignKey(Article) articles = ... # some queryset containing multiple articles If I want to find order operations containing at least one article, this works as expected: OrderOperation.objects.filter(ordered_articles__in=articles) However, if I want to find order operations with all the articles in the order, what is the correct way to do it?