python - 如何在Django模型中定义关系？

Question

我正在编写一个 Django 应用程序，用户可以在其中创建有关可用房间出租的帖子，并附有描述和图片。

我很难弄清楚如何定义模型中的关系。我认为用户类和地主类之间的关系将是多对一的关系。我的问题是，如何定义用户、房东和其他类(如rentalProperty、契约(Contract)和媒体)之间的关系。

谢谢。

from django.db import models
from django.contrib.auth.models import User

# Create your models here.


class Landlord(models.Model):
    user = models.ForeignKey("User", on_delete=models.PROTECT)
    address = models.CharField(max_length=255)
    social_security_number = models.CharField(max_length=255)
    email_address = models.CharField(max_length=255)


class rentalProperty(models.Model):
    landlord = models.ForeignKey("Landlord", on_delete=models.PROTECT)
    PROPERTY_LISTING_CHOICES = [
        (APARTMENT, 'Apartment'),
        (HOLIDAY_HOME, 'Holiday home'),
        (SINGLE_FAMILY_HOME, 'Single family home'),
        (COMMERCIAL, 'Commercial'),
    ]
    type_of_property_listing = models.CharField(
        max_length = 50,
        choices = PROPERTY_LISTING_CHOICES,
        default = APARTMENT
    )
    BUILDING_LISTING_CHOICES = [
        (CONDOMINIUM, 'Condominium'),
        (ROW_HOUSE, 'Row house'),
        (SINGLE_FAMILY_HOUSE, 'Single family house'),
        (HOLIDAY_HOME, 'Holiday_home'),
        (DUPLEX, 'Duplex'),
        (SINGLE_FAMILY_HOME_COOP, 'Single family home(CO-OP)'),
        (CONDOMINIUM_EXTERNAL_ENTRANCE, 'Condominium external entrance'),
        (WOODEN_COMDOMINIUM_HOUSE, 'Wooden condominium house')
    ]
    type_of_building_choices = models.CharField(
        max_length = 50,
        choices = BUILDING_LISTING_CHOICES,
        default = CONDOMINIUM
    )
    created_by = models.ForeignKey(User, related_name='rentalProperties')

class Location(models.Model):
    rental_property = models.ForeignKey("rentalProperty", on_delete=models.PROTECT)
    street = models.CharField(max_length=255)
    borough = models.CharField(max_length=255)
    postal_code = models.CharField(max_length=20)
    city = models.CharField(max_length=50)
    province = models.CharField(max_length=50)
    country = models.CharField(max_length=50)

class ApartmentBasicInfo(models.Model):
    location = models.ForeignKey("Location", on_delete=models.PROTECT)
    title = models.TextField()
    living_area = models.IntegerField()
    number_of_rooms = models.IntegerField()
    floors = models.IntegerField()
    furnished = models.BooleanField(initial=True)
    KITCHEN_TYPE_CHOICES = [
        (UNKNOWN, 'Unknown'),
        (NO_KITCHEN, 'No kitchen'),
        (KITCHEN, 'Kitchen'),
        (MINI_KITCHEN, 'Mini kitchen'),
        (OPEN_KITCHEN, 'Open kitchen')
    ]
    type_of_kitchen_choices = models.CharField(
        max_length = 50,
        choices = KITCHEN_TYPE_CHOICES,
        default = UNKNOWN
    ) 
    sauna = models.BooleanField(initial=True)
    balcony = models.BooleanField(initial=True)
    apartment_layout_type = models.IntegerField()
    APARTMENT_CONDITIONS_CHOICES = [
        (EXCELLENT, 'excellent'),
        (GOOD, 'good'),
        (FAIR, 'fair'),
        (POOR, 'poor'),
        (VERY_BAD, 'very bad')
    ]
    apartment_condition = models.CharField(
        max_length = 50,
        choices = APARTMENT_CONDITIONS_CHOICES,
        default = EXCELLENT
    )
    apartment_conditions_freetext = models.TextField()




class Contract(models.Model):
    rentalproperty = models.ForeignKey("rentalProperty", on_delete=models.PROTECT)
    RENTAL_TERMS_CHOICES = [
        (PERMANENT, 'permanent'),
        (FiXED, 'fixed'),
    ]
    type_of_rental_terms = models.CharField(
        max_length = 20,
        choices = RENTAL_TERMS_CHOICES,
        default = PERMANENT
    ) 
    rent_availability = models.DateField()
    rent_availability_info = models.TextField()
    rent_per_month = models.IntegerField()
    deposit_for_rent = models.IntegerField()
    deposit_for_rent_info = models.TextField()
    rental_increment = models.IntegerField()
    index_value = models.IntegerField()
    index_date = models.DateField()
    RENT_ELECTRICITY_CHOICES = [
        (UNDEFINED, 'undefined'),
        (INCLUDED_IN_THE_RENT, 'included in the rent'),
        (RESPONSIBILITY_OF_TENANT, 'responsibility of tenant'),
        (FIXED_FEE, 'fixed fee'),
        (OTHER, 'other')
    ]
    rent_electricity = models.CharField(
        max_length = 50,
        choices = RENTAL_TERMS_CHOICES,
        default = UNDEFINED
    )
    electricity_fixed_fee = models.IntegerField()
    WATER_FEE_CHOICES = [
        (UNDEFINED, 'undefined'),
        (INCLUDED_IN_THE_RENT, 'included in the rent'),
        (RESPONSIBILITY_OF_TENANT, 'responsibility of tenant'),
        (FIXED_FEE_PER_PERSON, 'fixed fee per person'),
        (OTHER, 'other')
    ]
    water_fee = models.CharField(
        max_length = 50,
        choices = WATER_FEE_CHOICES,
        default = UNDEFINED
    )
    water_fee_per_person = models.IntegerField()
    HEATING_FEE_CHOICES = [
         (UNDEFINED, 'undefined'),
        (INCLUDED_IN_THE_RENT, 'included in the rent'),
        (RESPONSIBILITY_OF_TENANT, 'responsibility of tenant'),
        (FIXED_FEE, 'fixed fee'),
        (OTHER, 'other')
    ]
    heating_fee = models.CharField(
        max_length = 50,
        choices = HEATING_FEE_CHOICES,
        default = UNDEFINED
    )
    heating_fixed_fee = models.IntegerField()
    Other_cost = models.TextField()
    pets_allowed = models.BooleanField(initial=True)
    smoking_allowed = models.BooleanField(initial=True)
    insurance_required = models.BooleanField(initial=True)
    other_terms = models.TextField()

class Media(models.Nodel):
    apartment_pictures = models.ImageField()
    videos = models.CharField(max_length=512)
    virtual_tours = models.CharField(max_length=512)

Answer 1

您的示例中有很多..很多错误。我认为这只是一个草稿。

我想展示一些修复和建议。

1. 在模型中，您应该使用 default而不是initial -initial正在使用 Forms .
2. 对于choices我想展示我如何解决choices以更简单的方式 - 只需使用 enum类
3. 使用OneToOne时关系，就像我的例子 Location ， RentalProperty.location 返回的对象是 Location 的一个实例类而不是 QuerySet - 在代码中更容易处理

from django.contrib.auth import get_user_model
from django.db import models
import enum


UserModel = get_user_model()


class ToChoicesEnum(enum.Enum):
    @classmethod
    def to_choices(cls):
        return tuple((tag.name, str(tag.value)) for tag in cls)


class Landlord(models.Model):
    user = models.ForeignKey(UserModel, on_delete=models.PROTECT)
    address = models.CharField(max_length=255)
    social_security_number = models.CharField(max_length=255)
    email_address = models.EmailField()


class RentalProperty(models.Model):
    landlord = models.ForeignKey("Landlord", on_delete=models.PROTECT)
    created_by = models.ForeignKey(UserModel, related_name='rentalProperties')

    class PropertyListingChoices(ToChoicesEnum):
        APARTMENT = 'Apartment'
        HOLIDAY_HOME = 'Holiday home'
        SINGLE_FAMILY_HOME = 'Single family home'
        COMMERCIAL = 'Commercial'

    type_of_property_listing = models.CharField(
        max_length=50,
        choices=PropertyListingChoices.to_choices(),
        default=PropertyListingChoices.APARTMENT
    )
    ...


class Location(models.Model):
    rental_property = models.OneToOneField("RentalProperty", related='location', on_delete=models.PROTECT)
    ...


class ApartmentBasicInfo(models.Model):
    rental_property = models.OneToOneField("RentalProperty", related='basic_info', on_delete=models.PROTECT)
    ...


class RentalImages(models.Model):
    rental_property = models.ForeignKey("RentalProperty", related='images', on_delete=models.PROTECT)
    apartment_picture = models.ImageField()


class RentalMedia(models.Model):
    class AssetTypeChoices(ToChoicesEnum):
        VIDEO = 'video'
        TOUR = 'tour'
    rental_property = models.ForeignKey("RentalProperty", related='rental_media', on_delete=models.PROTECT)
    asset_url = models.URLField()
    asset_type = models.CharField(max_length=10, choices=AssetTypeChoices.to_choices())


class Contract(models.Model):
    rental_property = models.ForeignKey("RentalProperty", related='contracts', on_delete=models.PROTECT)
    user = models.ForeignKey(UserModel, related='contracts', on_delete=models.PROTECT)
    smoking_allowed = models.BooleanField(default=True)  # in models you should use default instead initial
    ...