# pydantic_core._pydantic_core.ValidationError: 1 validation error for Order
customer_id
  字段必填 [type=missing, input_value={}, input_type=dict]

- **ID:** `python/pydantic-missing-field-required`
- **领域:** python
- **类别:** config_error
- **验证级别:** ai_generated
- **修复率:** 80%

## 根因

模型定义了无默认值的 customer_id 字段，但输入字典中未提供该值，Pydantic v2 抛出 missing 错误而非使用 None。

## 版本兼容性

| 版本 | 状态 | 引入 | 弃用 |
|------|------|------|------|
| 2.x | active | — | — |

## 解决方案

1. **** (98% 成功率)
   ```
   from typing import Optional
class Order(BaseModel):
    customer_id: Optional[int] = None
   ```
2. **** (97% 成功率)
   ```
   from pydantic import Field
class Order(BaseModel):
    items: list = Field(default_factory=list)
   ```

## 无效尝试

- **** — Type checker and Pydantic v2 will complain that None is not int; runtime validation still fails if None is passed explicitly. (70% 失败率)
- **** — extra controls unknown fields, not missing required fields. (90% 失败率)