The least painful and indeed Django-recommended way of doing this is through a OneToOneField(User) property. Extending the existing User model … If you wish to store information related to User, you can use a one-to-one relationship to a model containing the fields for additional information. This one-to-one model is often called a profile model, as … Read more
There is a simple solution for you called unique_together which does exactly what you want. For example: class MyModel(models.Model): field1 = models.CharField(max_length=50) field2 = models.CharField(max_length=50) class Meta: unique_together = (‘field1’, ‘field2′,) And in your case: class Volume(models.Model): id = models.AutoField(primary_key=True) journal_id = models.ForeignKey(Journals, db_column=’jid’, null=True, verbose_name = “Journal”) volume_number = models.CharField(‘Volume Number’, max_length=100) comments = … Read more
Differences between OneToOneField(SomeModel) and ForeignKey(SomeModel, unique=True) as stated in The Definitive Guide to Django: OneToOneField A one-to-one relationship. Conceptually, this is similar to a ForeignKey with unique=True, but the “reverse” side of the relation will directly return a single object. In contrast to the OneToOneField “reverse” relation, a ForeignKey “reverse” relation returns a QuerySet. Example … Read more
You could do this: Name.objects.exclude(alias__isnull=True) If you need to exclude null values and empty strings, the preferred way to do so is to chain together the conditions like so: Name.objects.exclude(alias__isnull=True).exclude(alias__exact=””) Chaining these methods together basically checks each condition independently: in the above example, we exclude rows where alias is either null or an empty string, … Read more
This is the behaviour to adopt when the referenced object is deleted. It is not specific to Django; this is an SQL standard. Although Django has its own implementation on top of SQL. (1) There are seven possible actions to take when such event occurs: CASCADE: When the referenced object is deleted, also delete the … Read more
A “slug” is a way of generating a valid URL, generally using data already obtained. For instance, a slug uses the title of an article to generate a URL. I advise to generate the slug by means of a function, given the title (or another piece of data), rather than setting it manually. An example: … Read more
Try DISABLE KEYS or SET FOREIGN_KEY_CHECKS=0; Make sure to SET FOREIGN_KEY_CHECKS=1; after.
You can use Q objects for this. They can be negated with the ~ operator and combined much like normal Python expressions: from myapp.models import Entry from django.db.models import Q Entry.objects.filter(~Q(id=3)) will return all entries except the one(s) with 3 as their ID: [<Entry: Entry object>, <Entry: Entry object>, <Entry: Entry object>, …]
null=True sets NULL (versus NOT NULL) on the column in your DB. Blank values for Django field types such as DateTimeField or ForeignKey will be stored as NULL in the DB. blank determines whether the field will be required in forms. This includes the admin and your custom forms. If blank=True then the field will … Read more