Just change the primary key of your object and run save(). obj = Foo.objects.get(pk=<some_existing_pk>) obj.pk = None obj.save() If you want auto-generated key, set the new key to None. More on UPDATE/INSERT here. Official docs on copying model instances: https://docs.djangoproject.com/en/2.2/topics/db/queries/#copying-model-instances
Any field with the auto_now attribute set will also inherit editable=False and therefore will not show up in the admin panel. There has been talk in the past about making the auto_now and auto_now_add arguments go away, and although they still exist, I feel you’re better off just using a custom save() method. So, to … Read more
Use Sample.objects.filter(date__range=[“2011-01-01”, “2011-01-31″]) Or if you are just trying to filter month wise: Sample.objects.filter(date__year=”2011″, date__month=”01”) Edit As Bernhard Vallant said, if you want a queryset which excludes the specified range ends you should consider his solution, which utilizes gt/lt (greater-than/less-than).
Essentially, you want to override the __init__ method of models.Model so that you keep a copy of the original value. This makes it so that you don’t have to do another DB lookup (which is always a good thing). class Person(models.Model): name = models.CharField() __original_name = None def __init__(self, *args, **kwargs): super().__init__(*args, **kwargs) self.__original_name = … Read more
https://docs.djangoproject.com/en/stable/topics/db/queries/#creating-objects To create and save an object in a single step, use the create() method.
As another option, you can do look ups like: class UserAdmin(admin.ModelAdmin): list_display = (…, ‘get_author’) def get_author(self, obj): return obj.book.author get_author.short_description = ‘Author’ get_author.admin_order_field = ‘book__author’ Since Django 3.2 you can use display() decorator: class UserAdmin(admin.ModelAdmin): list_display = (…, ‘get_author’) @display(ordering=’book__author’, description=’Author’) def get_author(self, obj): return obj.book.author
There are many ways to convert an instance to a dictionary, with varying degrees of corner case handling and closeness to the desired result. 1. instance.__dict__ instance.__dict__ which returns {‘_foreign_key_cache’: <OtherModel: OtherModel object>, ‘_state’: <django.db.models.base.ModelState at 0x7ff0993f6908>, ‘auto_now_add’: datetime.datetime(2018, 12, 20, 21, 34, 29, 494827, tzinfo=<UTC>), ‘foreign_key_id’: 2, ‘id’: 1, ‘normal_value’: 1, ‘readonly_value’: 2} This … Read more
There are a couple of ways: To delete it directly: SomeModel.objects.filter(id=id).delete() To delete it from an instance: instance = SomeModel.objects.get(id=id) instance.delete()
Your understanding is mostly correct. You use select_related when the object that you’re going to be selecting is a single object, so OneToOneField or a ForeignKey. You use prefetch_related when you’re going to get a “set” of things, so ManyToManyFields as you stated or reverse ForeignKeys. Just to clarify what I mean by “reverse ForeignKeys” … Read more
If you mean to do aggregation you can use the aggregation features of the ORM: from django.db.models import Count result = (Members.objects .values(‘designation’) .annotate(dcount=Count(‘designation’)) .order_by() ) This results in a query similar to SELECT designation, COUNT(designation) AS dcount FROM members GROUP BY designation and the output would be of the form [{‘designation’: ‘Salesman’, ‘dcount’: 2}, … Read more