在Django中,foreign_key是一种关系字段,用于在模型之间建立关联关系。 在模板上访问通过foreign_key建立的关联数据时,可以通过以下步骤进行操作: 确保在模型中正确地定义了foreign_key字段。例如,如果一个模型A有一个foreign_key字段指向另一个模型B,那么在模型A中应该有类似于foreign_key = models.ForeignKey(...
django app目录下的models.py 创建表: class UserInfo(models.Mode): username=models.CharField(max_length=32) password=models.CharField(max_length=32) gender_list=( (1,'男'), (2,'女'), ) gender=models.IntegerField(choices=gender_list) class U2U(models.Model): 利用一张表创建出 男生对应约会...
from django.db import models """A model pair to map car and its manufacturer"""classManufacturer(models.Model): brand= models.CharField(max_length=100) location= models.CharField(max_length=100)def__unicode__(self):returnself.brandclassMeta: ordering= ["brand"]classCar(models.Model): owner...
It works fine with just one of the two foreign key fields declared. Is it possible to have two foreign key fields to the same model in an abstract class, and if so, how do I set it up? python django django-models Share Improve this question Follow edited Jun 20, 2020 at 9:12 Co...
I'm trying to filter by a value that is contained in a foreign key. I've seen this done in the django documentation (the blog example). Here are my models: class Students(models.Model): ssn = models.CharField(unique=True, maxlength=11) name = models.CharField(blank=True, maxlength=50...
django.db.utils.IntegrityError: FOREIGN KEY constraint failed STATUS MODEL EDDIT Maybe problem is here. The problem is appeared after i added some code which you can see in comments. "This last error suggests that the Status with pk=1 already exists, but your previous error suggests the contr...
models import Bar, Foo class BarFilter(django_filters.FilterSet): foo = django_filters.ModelMultipleChoiceFilter( queryset=Foo.objects.all(), widget=CheckboxSelectMultiple(), label="Foo", label_suffix="", ) class Meta: model = bar fields = ['foo'] This works totally fine in the view....
组件:Database layer (models, ORM)→Migrations It seems likethis should be addressable by defining aForeignKey.db_collationproperty that proxiesself.target_field.db_column 表式标准django/db/models/fields/related.py diff --git a/django/db/models/fields/related.py b/django/db/models/fields/rel...
django.db.utils.IntegrityError: foreign key constraint failed 是一个常见的数据库错误,表明在尝试插入或更新数据库记录时违反了外键约束。这通常意味着你尝试将一条记录的外键字段设置为一个不存在的关联记录的主键。 常见原因 关联对象不存在:当你尝试插入或更新一个外键字段时,如果指定的关联对象在数据库中不存在...
如果在 rule 中查询 rule.allowed,Django 会自动锁定外键对应的表为 robots_rule_allowed 通过查询这个表得到对应的 url_id(多个),然后去 robots_url 表中提取相应记录。 2、ForeignKey class ThreadedComment(models.Model): ... # Generic Foreign Key Fields content...