克隆一个Django模型实例对象，并将其保存到另一个具有相同字段的模型中

from django.db.models import Model
from django.db.models.fields.related import ForeignKey, OneToOneField, ManyToManyField
from django.db.models.fields.reverse_related import ManyToOneRel, OneToOneRel
from django.db.models.fields import FieldDoesNotExist

def clone_model_instance(instance):
    # 获取模型类
    ModelClass = instance.__class__

    # 创建一个新的模型实例对象
    new_instance = ModelClass()

    # 遍历模型的所有字段
    for field in ModelClass._meta.get_fields():
        # 排除自增主键字段
        if field.auto_created:
            continue

        # 获取字段的名称
        field_name = field.name

        try:
            # 获取字段的值
            field_value = getattr(instance, field_name)
        except FieldDoesNotExist:
            continue

        # 处理外键字段
        if isinstance(field, (ForeignKey, OneToOneField)):
            # 如果外键字段为空，则跳过
            if field_value is None:
                continue

            # 获取关联模型类
            RelatedModelClass = field.related_model

            # 获取关联模型实例对象
            related_instance = getattr(instance, field_name)

            # 递归调用克隆函数，克隆关联模型实例对象
            cloned_related_instance = clone_model_instance(related_instance)

            # 设置新模型实例对象的外键字段值
            setattr(new_instance, field_name, cloned_related_instance)

        # 处理多对多字段
        elif isinstance(field, ManyToManyField):
            # 获取多对多关联模型类
            RelatedModelClass = field.related_model

            # 获取多对多关联模型实例对象列表
            related_instances = getattr(instance, field_name).all()

            # 创建一个新的多对多关联模型实例对象列表
            cloned_related_instances = []

            # 遍历多对多关联模型实例对象列表，递归调用克隆函数，克隆关联模型实例对象
            for related_instance in related_instances:
                cloned_related_instance = clone_model_instance(related_instance)
                cloned_related_instances.append(cloned_related_instance)

            # 设置新模型实例对象的多对多字段值
            setattr(new_instance, field_name, cloned_related_instances)

        # 处理其他字段
        else:
            # 设置新模型实例对象的字段值
            setattr(new_instance, field_name, field_value)

    # 保存新模型实例对象到数据库
    new_instance.save()

    # 返回新模型实例对象
    return new_instance

# 假设有两个模型类：ModelA和ModelB，它们具有相同的字段
# 克隆ModelA的实例对象到ModelB中
model_a_instance = ModelA.objects.get(pk=1)
cloned_model_b_instance = clone_model_instance(model_a_instance)