File upload using FastAPI returns error 422-CodePudding

I am using the example from the official documentation: https://fastapi.tiangolo.com/tutorial/request-files/#import-file

Server code:

@app.post("/uploadfile")
async def create_upload_file(data: UploadFile = File(...)):
    print("> uploaded file:",data.filename)
    return {"filename": data.filename}

Client code:

files = {'upload_file': open('config.txt', 'rb')}
resp = requests.post(
        url = URL,
        files = files)
print(resp.json())

The problem is that the server always responds with error 422:

{'detail': [{'loc': ['body', 'data'], 'msg': 'field required', 'type': 'value_error.missing'}]}

I am using Python 3 on both server and client and the python-multipart package is already installed.

Can someone please tell me what I am doing wrong, what am I missing, how should I fix the code?

Any hints are much appreciated.

CodePudding user response：

Well, I just realized my error (which is not immediately obvious for newbies like me :))

The parameter you pass on client side ('upload_file')

files = {'upload_file': open('config.txt', 'rb')}

must match the parameter on the server side ('data'):

async def create_upload_file(data: UploadFile = File(...)):

So in order to work I had to rename on client side 'upload_file' to 'data':

files = {'data': open('config.txt', 'rb')} # renamed 'upload_file' to 'data'

That's it. Hopefully this helps some others as well.

CodePudding user response：

On client side you should use the key you gave on server side. In your case, that is data. Thus, you should replace upload_file with data, as shown below:

files = {'data': open('config.txt', 'rb')}