如何在 FastAPI POST 请求中同时提交 JSON 和文件？

如何在 FastAPI POST 请求中同时添加文件和 JSON 正文？

在 FastAPI 中，您无法同时发送 JSON 数据和文件如果您将正文声明为 JSON，则为单个请求。相反，您需要使用 multipart/form-data 编码。以下是实现此目的的几种方法：

方法 1：使用文件和表单

# Assuming you have a DataConfiguration model for the JSON data
from fastapi import FastAPI, File, UploadFile
from pydantic import BaseModel

app = FastAPI()

class DataConfiguration(BaseModel):
    textColumnNames: list[str]
    idColumn: str

@app.post("/data")
async def data(dataConfiguration: DataConfiguration,
               csvFile: UploadFile = File(...)):
    pass  # read requested id and text columns from csvFile

方法 2：使用 Pydantic 模型和依赖项

from fastapi import FastAPI, Form, File, UploadFile, Depends, Request
from pydantic import BaseModel
from typing import List, Optional, Dict
from fastapi.responses import HTMLResponse
from fastapi.templating import Jinja2Templates

app = FastAPI()
templates = Jinja2Templates(directory="templates")

class Base(BaseModel):
    name: str
    point: Optional[float] = None
    is_accepted: Optional[bool] = False

def validate_json_body(body: str = Form(...)):
    try:
        return Base.model_validate_json(body)
    except ValidationError as e:
        raise HTTPException(
            detail=jsonable_encoder(e.errors()),
            status_code=422,
        )

@app.post("/submit")
async def submit(base: Base = Depends(validate_json_body),
                  files: List[UploadFile] = File(...)):
    return {
        "JSON Payload": base,
        "Filenames": [file.filename for file in files],
    }

@app.get("/", response_class=HTMLResponse)
async def main(request: Request):
    return templates.TemplateResponse("index.html", {"request": request})

方法 3：将 JSON 传递为Body参数中的字符串

from fastapi import FastAPI, Form, UploadFile, File
from pydantic import BaseModel

class Base(BaseModel):
    name: str
    point: float
    is_accepted: bool

app = FastAPI()

@app.post("/submit")
async def submit(data: Base = Form(...), files: List[UploadFile] = File(...)):
    return {
        "JSON Payload": data,
        "Filenames": [file.filename for file in files],
    }

方法四：使用自定义类验证JSON

from fastapi import FastAPI, File, UploadFile, Request
from pydantic import BaseModel, model_validator
from typing import Optional, List
from fastapi.responses import HTMLResponse
from fastapi.templating import Jinja2Templates
import json

app = FastAPI()
templates = Jinja2Templates(directory="templates")

class Base(BaseModel):
    name: str
    point: Optional[float] = None
    is_accepted: Optional[bool] = False

    @model_validator(mode='before')
    @classmethod
    def validate_to_json(cls, value):
        if isinstance(value, str):
            return cls(**json.loads(value))
        return value

@app.post("/submit")
async def submit(data: Base = Body(...), files: List[UploadFile] = File(...)):
    return {
        "JSON Payload": data,
        "Filenames": [file.filename for file in files],
    }

@app.get("/", response_class=HTMLResponse)
async def main(request: Request):
    return templates.TemplateResponse("index.html", context={"request": request})

注意：中方法1，您可以同时使用File 和Form 类，因为Form 是Body 的子类。但是，如果您在方法 1 中使用 Body(...) 而不是 Form(...)，它将不起作用，因为 FastAPI 会期望 JSON 数据位于请求正文中，而不是表单数据。

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