我有不同的型号。一个模型的Multiselctfield的选择依赖于另一个模型。因此,必须在model.py中查询数据库,同时这样做,这会导致迁移问题。 (表不存在错误)
class Invigilator(models.Model):
---
# this method queries Shift objects and Examroom
def get_invigilator_assignment_list ():
assignment = []
shifts = Shift.objects.all()
for shift in shifts:
rooms= ExamRoom.objects.all()
for room in rooms:
assign = str (shift.shiftName)+ " " +str (room.name)
assignment.append (assign)
return assignment
assignment_choice = []
assign = get_invigilator_assignment_list()
i = 0
for assignm in assign:
datatuple = (i,assignm)
assignment_choice.append(datatuple)
i= i+1
ASSIGNMENT_CHOICE = tuple(assignment_choice)
assignment =MultiSelectField (choices = ASSIGNMENT_CHOICE, blank = True, verbose_name="Assignments")
最佳答案
您无法添加动态选择,因为它们都存储在迁移文件和表信息中。如果 Django 允许你这样做,这意味着每次有人向这两个模型添加一条记录时,都应该创建一个新的迁移并更改数据库。您必须以不同的方式解决这个问题。
据我所知 django-smart-selects 有一个 ChainedManyToMany
字段可以做到这一点。
这是存储库中的示例。
from smart_selects.db_fields import ChainedManyToManyField
class Publication(models.Model):
name = models.CharField(max_length=255)
class Writer(models.Model):
name = models.CharField(max_length=255)
publications = models.ManyToManyField('Publication', blank=True, null=True)
class Book(models.Model):
publication = models.ForeignKey(Publication)
writer = ChainedManyToManyField(
Writer,
chained_field="publication",
chained_model_field="publications")
name = models.CharField(max_length=255)
关于python - 如何在 Django 中从 models.py 查询数据库项?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/54149411/