模式的额外信息 - 例子

您可以在JSON模式中定义额外的信息。

一个常见的用例是添加一个将在文档中显示的example。

有几种方法可以声明额外的 JSON 模式信息。

Pydantic schema_extra

您可以使用 Config 和 schema_extra 为Pydantic模型声明一个示例，如Pydantic 文档：定制 Schema中所述:

Python 3.10+Python 3.8+

from fastapi import FastAPI
from pydantic import BaseModel
app = FastAPI()
class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None
    model_config = {
        "json_schema_extra": {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ]
        }
    }
@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):
    results = {"item_id": item_id, "item": item}
    return results

from typing import Union
from fastapi import FastAPI
from pydantic import BaseModel
app = FastAPI()
class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    model_config = {
        "json_schema_extra": {
            "examples": [
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ]
        }
    }
@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):
    results = {"item_id": item_id, "item": item}
    return results

这些额外的信息将按原样添加到输出的JSON模式中。

Field 的附加参数

在 Field, Path, Query, Body 和其他你之后将会看到的工厂函数，你可以为JSON 模式声明额外信息，你也可以通过给工厂函数传递其他的任意参数来给JSON 模式声明额外信息，比如增加 example:

Python 3.10+Python 3.8+

from fastapi import FastAPI
from pydantic import BaseModel, Field
app = FastAPI()
class Item(BaseModel):
    name: str = Field(examples=["Foo"])
    description: str | None = Field(default=None, examples=["A very nice Item"])
    price: float = Field(examples=[35.4])
    tax: float | None = Field(default=None, examples=[3.2])
@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):
    results = {"item_id": item_id, "item": item}
    return results

from typing import Union
from fastapi import FastAPI
from pydantic import BaseModel, Field
app = FastAPI()
class Item(BaseModel):
    name: str = Field(examples=["Foo"])
    description: Union[str, None] = Field(default=None, examples=["A very nice Item"])
    price: float = Field(examples=[35.4])
    tax: Union[float, None] = Field(default=None, examples=[3.2])
@app.put("/items/{item_id}")
async def update_item(item_id: int, item: Item):
    results = {"item_id": item_id, "item": item}
    return results

Warning

请记住，传递的那些额外参数不会添加任何验证，只会添加注释，用于文档的目的。

Body 额外参数

你可以通过传递额外信息给 Field 同样的方式操作Path, Query, Body等。

比如，你可以将请求体的一个 example 传递给 Body:

Python 3.10+Python 3.9+Python 3.8+Python 3.10+ non-AnnotatedPython 3.8+ non-Annotated

from typing import Annotated
from fastapi import Body, FastAPI
from pydantic import BaseModel
app = FastAPI()
class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None
@app.put("/items/{item_id}")
async def update_item(
    item_id: int,
    item: Annotated[
        Item,
        Body(
            examples=[
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ],
        ),
    ],
):
    results = {"item_id": item_id, "item": item}
    return results

from typing import Annotated, Union
from fastapi import Body, FastAPI
from pydantic import BaseModel
app = FastAPI()
class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
@app.put("/items/{item_id}")
async def update_item(
    item_id: int,
    item: Annotated[
        Item,
        Body(
            examples=[
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ],
        ),
    ],
):
    results = {"item_id": item_id, "item": item}
    return results

from typing import Union
from fastapi import Body, FastAPI
from pydantic import BaseModel
from typing_extensions import Annotated
app = FastAPI()
class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
@app.put("/items/{item_id}")
async def update_item(
    item_id: int,
    item: Annotated[
        Item,
        Body(
            examples=[
                {
                    "name": "Foo",
                    "description": "A very nice Item",
                    "price": 35.4,
                    "tax": 3.2,
                }
            ],
        ),
    ],
):
    results = {"item_id": item_id, "item": item}
    return results

Tip

尽可能选择使用 Annotated 的版本。

from fastapi import Body, FastAPI
from pydantic import BaseModel
app = FastAPI()
class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None
@app.put("/items/{item_id}")
async def update_item(
    item_id: int,
    item: Item = Body(
        examples=[
            {
                "name": "Foo",
                "description": "A very nice Item",
                "price": 35.4,
                "tax": 3.2,
            }
        ],
    ),
):
    results = {"item_id": item_id, "item": item}
    return results

Tip

尽可能选择使用 Annotated 的版本。

from typing import Union
from fastapi import Body, FastAPI
from pydantic import BaseModel
app = FastAPI()
class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
@app.put("/items/{item_id}")
async def update_item(
    item_id: int,
    item: Item = Body(
        examples=[
            {
                "name": "Foo",
                "description": "A very nice Item",
                "price": 35.4,
                "tax": 3.2,
            }
        ],
    ),
):
    results = {"item_id": item_id, "item": item}
    return results

文档 UI 中的例子

使用上面的任何方法，它在 /docs 中看起来都是这样的:

技术细节

关于 example 和 examples…

JSON Schema在最新的一个版本中定义了一个字段 examples ，但是 OpenAPI 基于之前的一个旧版JSON Schema，并没有 examples.

所以 OpenAPI为了相似的目的定义了自己的 example (使用 example, 而不是 examples), 这也是文档 UI 所使用的 (使用 Swagger UI).

所以，虽然 example 不是JSON Schema的一部分，但它是OpenAPI的一部分，这将被文档UI使用。

其他信息

同样的方法，你可以添加你自己的额外信息，这些信息将被添加到每个模型的JSON模式中，例如定制前端用户界面，等等。