Django-已从另一个模型中选择的模型选择

Question

So I have one model AdminChoices that has a ManytoMany field which selects choices from another model choices . I want another model that has a ManytoMany field who's choices are only the selected choices of AdminChoices . Here is the current code for the models.

class choices(models.Model):
    choices = models.CharField(max_length=300)

    def __str__(self):
        return self.choices

class AdminChoices(models.Model):
    choice1 = models.ManytoManyFields(choices, related_name="adminchoices_choice1_related")
    choice2 = models.ManytoManyFields(choices, related_name="adminchoices_choice2_related")
    etc

class UserChoices(models.Model):
    choice1 = "choice that can only be chosen from selected AdminChoices choice1"
    choice2 = "AdminChoices choice2"
    etc

I'm making an application where users can create a hardware configuration. A field in this model represents a slot and only one choice can be selected for the slot. These choices would have to be approved by an admin first to ensure that the slot can accept that choice. This is where the AdminChoices model comes in, where an admin would have access to a global admin configuration that approves choices for a slot, which would then allow a user to select one of the approved choices in their personal configuration.

I'm not sure if I'm taking the right approach, how would I go about making this model?

Answer 1

Note that this is not an as easy task as one might think. The simplest way to achieve this would be to re-structure your database like this:

class Choice(models.Model):
    choice = models.CharField(max_length=300)

    def __str__(self):
        return self.choice

class User(models.Model):
    username=models.CharField(max_length=300)

class SlotChoice(models.Model):
    slotname=models.CharField(max_length=300)
    choice = models.ForeignKey(Choice, related_name="adminchoices_related")
    def __str__(self):
        return self.slotname + " " +self.choice.choice

class UserChoice(models.Model):
    user = models.ForeignKey(User)
    choice = models.ForeignKey(SlotChoice)

This is simple but slightly different from what you asked. You can make this more usable by tweaking the " str " method of the SlotChoice model as shown above.

However, if you want to really make this work more along the lines of your original question it is slightly more difficult. To really make something like this work smoothly you will need to use JavaScript: your form does not know what slot you have selected when loading so you need to change the choice dropdown when changing the slot dropdown. One neat way to do this is the module django-smart-selects . This is easy to use - also for beginners - it adds the JS magically. Then your models would look something like this:

 from smart_selects.db_fields import ChainedForeignKey
    class Choice(models.Model):
        choice = models.CharField(max_length=300)

        def __str__(self):
            return self.choice

class User(models.Model):
    username=models.CharField(max_length=300)

class Slot(models.Model):
    slotname=models.CharField(max_length=300)


class SlotChoice(models.Model):
    slot=models.ForeignKey(Slot)
    choices = models.ManytoManyFields(Choice, related_name="adminchoices_related")

class UserChoice(models.Model):
    user = models.ForeignKey(User)
    slot = models.ForeignKey(Slot)

    choice = = ChainedForeignKey(
    SlotChoice,
    chained_field="slot",
    chained_model_field="slot",
    show_all=False,
    auto_choose=True,
    sort=True)