Django 模型设计：避免保留字与正确处理关联模型的多对多子属性

from django.db import models

class SubAssetType(models.Model):
    name = models.CharField(max_length=50)
    slug = models.SlugField()
    descripcion = models.TextField(null=True, blank=True)

    def __str__(self):
        return self.name

class AssetType(models.Model):
    name = models.CharField(max_length=50)
    slug = models.SlugField()
    descripcion = models.TextField(null=True, blank=True)
    subtipos = models.ManyToManyField(SubAssetType, blank=True)

    def __str__(self):
        return self.name

class Asset(models.Model):
    # Atributos nominales
    name = models.CharField(max_length=50)
    slug = models.SlugField()
    descripcion = models.TextField(null=True, blank=True)
    # Atributos de valor
    # 将 'type' 重命名为 'tipo' 或 'asset_type'
    tipo = models.ForeignKey(AssetType, on_delete=models.CASCADE, related_name='assets_by_type')
    # subtipo 的正确定义将在下一节讨论
    # subtipo = models.ForeignKey(SubAssetType, on_delete=models.CASCADE, related_name='assets_by_subtype')

    def __str__(self):
        return self.name

from django.db import models
from django.core.exceptions import ValidationError

# ... (SubAssetType and AssetType models as defined previously)

class Asset(models.Model):
    # Atributos nominales
    name = models.CharField(max_length=50)
    slug = models.SlugField()
    descripcion = models.TextField(null=True, blank=True)
    # Atributos de valor
    tipo = models.ForeignKey(AssetType, on_delete=models.CASCADE, related_name='assets_by_type')
    # subtipo 直接指向 SubAssetType 模型
    subtipo = models.ForeignKey(SubAssetType, on_delete=models.CASCADE, related_name='assets_by_subtype')

    def __str__(self):
        return self.name

    # 强制业务逻辑约束的方法将在 clean() 方法中实现
    def clean(self):
        super().clean()
        # 只有当 tipo 和 subtipo 都已选择时才进行验证
        if self.tipo and self.subtipo:
            # 检查所选的 subtipo 是否在当前 tipo 的 subtipos 列表中
            if not self.tipo.subtipos.filter(pk=self.subtipo.pk).exists():
                raise ValidationError(
                    {'subtipo': '所选的子类型不属于当前资产类型。请选择与资产类型匹配的子类型。'}
                )

from django.db import models
from django.core.exceptions import ValidationError

# ... (SubAssetType and AssetType models)

class Asset(models.Model):
    # ... (fields as defined above)
    tipo = models.ForeignKey(AssetType, on_delete=models.CASCADE, related_name='assets_by_type')
    subtipo = models.ForeignKey(SubAssetType, on_delete=models.CASCADE, related_name='assets_by_subtype')

    def __str__(self):
        return self.name

    def clean(self):
        """
        自定义验证方法，确保 subtipo 属于 tipo 的 subtipos 列表。
        """
        super().clean() # 调用父类的 clean 方法

        # 只有当 tipo 和 subtipo 都已设置时才进行验证
        if self.tipo and self.subtipo:
            # 使用 .filter().exists() 是查询关联对象最高效的方式
            if not self.tipo.subtipos.filter(pk=self.subtipo.pk).exists():
                raise ValidationError(
                    {'subtipo': '所选的子类型不属于当前资产类型。请选择与资产类型匹配的子类型。'}
                )

from django import forms
from .models import Asset, AssetType, SubAssetType

class AssetForm(forms.ModelForm):
    class Meta:
        model = Asset
        fields = '__all__' # 或者指定需要包含的字段

    def clean(self):
        """
        自定义表单验证方法，确保 subtipo 属于 tipo 的 subtipos 列表。
        """
        cleaned_data = super().clean()
        tipo = cleaned_data.get('tipo')
        subtipo = cleaned_data.get('subtipo')

        # 只有当 tipo 和 subtipo 都存在于表单数据中时才进行验证
        if tipo and subtipo:
            if not tipo.subtipos.filter(pk=subtipo.pk).exists():
                self.add_error('subtipo', '所选的子类型不属于当前资产类型。') # 将错误添加到特定字段

        return cleaned_data