动态 django 选择字段

Question

I have 4 models: Products (the list of products: freezers, microwaves, tvs and pcs), ProductType (entertainment and home appliances), Credit (a credit is registered on each purchase) and PurchaseReason (the reason why the customer has bought the product).

The PurchaseReason depend on the productType , so the purchaseReason has a foreignKey field productType .

In addition, each credit has a product as foreignKey and a purchaseReason as foreignKey.

Also, I have the ProductReason field as a choice field in the credit model, and I want the options to be set dynamically based on the product field of the credit model.

I'm creating an API so I think this cant be handle with modelForms, but i'm not sure. The hard work would be with the serializers (DRF) and with the django-admin (specially this one because in my product the django admin plays an important role)

What would be the best approach to manage my models in Django?

Here are my models. In credit I'm not sure how to implemente the purchase reason:

class Credit(models.Model):
    client = models.ForeignKey('clients.Client', on_delete=models.SET_NULL)
    name = models.CharField(max_length=30, null=False, blank=True)
    product = models.ForeignKey('product',on_delete=models.SET_NULL)
    reason_purchase = models.ChoiceField(????)

class PurchaseReason(models.Model):
    product_type = models.ForeignKey(product_type, on_delete=models.CASCADE)
    reason = models.CharField(max_length=30, null=False, blank=True)

class ProductType(models.Model):
    name = models.CharField(max_length=30, null=False, blank=False)

class Product(models.Model):
    model = models.CharField(max_length=30, default=None, null=True)
    product_type = models.ForeignKey(product_type, on_delete=models.CASCADE)

Answer 1

When we use the foreign key, we need to mention the model name of that particular model so that we can integrate that particular model in that model as a reference entity. Have a look at this example.

from django.db import models

class Reporter(models.Model):
    first_name = models.CharField(max_length=30)
    last_name = models.CharField(max_length=30)
    email = models.EmailField()

    def __str__(self):
        return "%s %s" % (self.first_name, self.last_name)

class Article(models.Model):
    headline = models.CharField(max_length=100)
    pub_date = models.DateField()
    reporter = models.ForeignKey(Reporter, on_delete=models.CASCADE)

    def __str__(self):
        return self.headline

    class Meta:
        ordering = ['headline']

you've not mentioned the model name properly. it should be Product in place of 'product' in the Credit class, product field.

use this reference https://docs.djangoproject.com/en/3.2/topics/db/examples/many_to_one/

i think you should be able to use the Foreignkey field properly after this. Although, if you can't, you can share the actual objective. i will help you to write the correct model. Best wishes:)