pydantic

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from pydantic import BaseModel
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class User(BaseModel):
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    name: str
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    age: int
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user = User(name="John", age=42)
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print(user)

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from typing import Any, Dict, List, Optional, Union
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from pydantic import BaseModel, Field
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class DataModel(BaseModel):
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    list: Optional[List[Dict[str, Any]]] = Field(default=None, description="数据列表")
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    page: int = Field(default=1, description="当前页码")
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    page_size: int = Field(default=30, description="每页数量")
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    total: int = Field(default=0, description="总数据量")
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class ResponseModel(BaseModel):
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    id: Union[str, int] = Field(description="请求ID")
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    success: bool = Field(default=True, description="是否成功")
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    data: DataModel
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    message: Optional[str] = Field(default=None, description="错误信息")
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data = {
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    "id": 42,
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    "data": {
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        "list": [],
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        "page": 1,
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        "page_size": 30,
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        "total": 100,
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    },
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}
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response = ResponseModel(**data)

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# 返回字典
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response.model_dump()
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# {'id': 42, 'success': True, 'data': {'list': [], 'page': 1, 'page_size': 30, 'total': 100}, 'message': None}
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# 仅返回指定字段
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response.model_dump(include={"id", "data"})
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#{'id': 42, 'data': {'list': [], 'page': 1, 'page_size': 30, 'total': 100}}
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# 排除指定字段
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response.model_dump(exclude={"message"})
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#{'id': 42, 'success': True, 'data': {'list': [], 'page': 1, 'page_size': 30, 'total': 100}}
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# 使用别名
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response.model_dump(by_alias=True)
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# {'id': 42, 'success': True, 'data': {'list': [], 'page': 1, 'size': 30, 'total': 100}, 'message': None}
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# 排除默认值
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response.model_dump(exclude_defaults=True)
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# {'id': 42, 'data': {'list': [], 'total': 100}}
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# 排除 None
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response.message = None
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>>> response.model_dump(exclude_none=True)
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# {'id': 42, 'success': True, 'data': {'list': [], 'page': 1, 'page_size': 30, 'total': 100}}

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# 把模型转换为 JSON
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response.model_dump_json()
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'{"id":42,"success":true,"data":{"list":[],"page":1,"page_size":30,"total":100},"message":null}'

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from pydantic import ValidationError
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def format_validation_error(e: ValidationError) -> str:
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    """格式化验证错误，提取具体的字段错误信息"""
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    if not isinstance(e, ValidationError):
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        return ""
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    error_msgs = []
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    for error in e.errors():
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        field = ".".join(str(loc) for loc in error["loc"])
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        msg = f"{field}: {error['msg']}"
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        error_msgs.append(msg)
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    return "; ".join(error_msgs)