-1

I wrote a small flask server. The purpose is to upload files. The important part, is that this is a server which has only a REST API and doesn't render html and template files.

This is the code:

from flask import Flask, render_template, request, redirect, url_for

app = Flask(__name__)

@app.route('/')
def index():
    return render_template('index.html')

@app.route('/', methods=['POST'])
def upload_file():
    uploaded_file = request.files['file']
    if uploaded_file.filename != '':
        uploaded_file.save(uploaded_file.filename)
    return redirect(url_for('index'))
    
if __name__ == "__main__":
    app.run(debug=True)

I triggered this server using curl:

curl -X POST -d file=/home/user1/Desktop/STEP_files/MyFile.txt 127.0.0.1:5000

However, i got this back:

  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/werkzeug/datastructures.py", line 442, in __getitem__
    raise exceptions.BadRequestKeyError(key)
werkzeug.exceptions.BadRequestKeyError: 400 Bad Request: The browser (or proxy) sent a request that this server could not understand.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 2464, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 2450, in wsgi_app
    response = self.handle_exception(e)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1867, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/user1/Desktop/flaskServer/server.py", line 11, in upload_file
    uploaded_file = request.files['file']
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/debughelpers.py", line 100, in __getitem__
    raise DebugFilesKeyError(request, key)
flask.debughelpers.DebugFilesKeyError: You tried to access the file "file" in the request.files dictionary but it does not exist.  The mimetype for the request is "application/x-www-form-urlencoded" instead of "multipart/form-data" which means that no file contents were transmitted.  To fix this error you should provide enctype="multipart/form-data" in your form.

The browser instead transmitted some file names. This was submitted: "/home/user1/Desktop/STEP_files/MyFile.txt"

The error messages are not very straightforward to me... I programmed the server by the book (keep in mind, this is my first flask server). Not sure what went wrong, or what did i do wrong....

EDIT: It seems like i am able to send the file succesfully with curl, but the file is not saved in the folder that the server exists...

EDIT2: If i do curl -X POST -F 'file=/home/user1/Desktop/STEP_files/MyFile.txt' 127.0.0.1:5000 as Mindslave suugested, i get:

127.0.0.1 - - [02/Feb/2021 16:49:37] "POST / HTTP/1.1" 500 -
Traceback (most recent call last):
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 2464, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 2450, in wsgi_app
    response = self.handle_exception(e)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1867, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/user1/Desktop/flaskServer/server.py", line 11, in upload_file
    uploaded_file = request.files['file']
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/werkzeug/datastructures.py", line 442, in __getitem__
    raise exceptions.BadRequestKeyError(key)
werkzeug.exceptions.BadRequestKeyError: 400 Bad Request: The browser (or proxy) sent a request that this server could not understand.
KeyError: 'file'

And if i do curl -X POST -d "file=@/home/user1/Desktop/STEP_files/MyFile.txt" 127.0.0.1:5000

i get:

127.0.0.1 - - [02/Feb/2021 16:53:11] "POST / HTTP/1.1" 500 -
Traceback (most recent call last):
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/debughelpers.py", line 96, in __getitem__
    return oldcls.__getitem__(self, key)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/werkzeug/datastructures.py", line 442, in __getitem__
    raise exceptions.BadRequestKeyError(key)
werkzeug.exceptions.BadRequestKeyError: 400 Bad Request: The browser (or proxy) sent a request that this server could not understand.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 2464, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 2450, in wsgi_app
    response = self.handle_exception(e)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1867, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 2447, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1952, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1821, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/_compat.py", line 39, in reraise
    raise value
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1950, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/app.py", line 1936, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/user1/Desktop/flaskServer/server.py", line 11, in upload_file
    uploaded_file = request.files['file']
  File "/home/user1/anaconda3/envs/flaskTest/lib/python3.9/site-packages/flask/debughelpers.py", line 100, in __getitem__
    raise DebugFilesKeyError(request, key)
flask.debughelpers.DebugFilesKeyError: You tried to access the file "file" in the request.files dictionary but it does not exist.  The mimetype for the request is "application/x-www-form-urlencoded" instead of "multipart/form-data" which means that no file contents were transmitted.  To fix this error you should provide enctype="multipart/form-data" in your form.

The browser instead transmitted some file names. This was submitted: "@/home/user1/Desktop/STEP_files/Assembly_Test.step"
Improve this question
5
  • try 'curl -X POST -F 'file=/home/user1/Desktop/STEP_files/MyFile.txt' 127.0.0.1:5000' Commented Feb 2, 2021 at 14:28
  • Alternative to that, it should also work to prepend an @ to the filename, that would then be: curl -X POST -d "file=@/home/user1/Desktop/STEP_files/MyFile.txt" 127.0.0.1:5000 Commented Feb 2, 2021 at 14:32
  • @Mindslave Thank you. I tried the things you suggested. But they did not work. I updated my question with your approaches and the errors i got. Commented Feb 2, 2021 at 14:54
  • Hm, -F seems to get us closer, since it does not complain about the mimetype anymore. Can you also try using the @ syntax with -F? That is curl -X POST -F file=@/home/user1/Desktop/STEP_files/MyFile.txt 127.0.0.1:5000 Commented Feb 2, 2021 at 15:00
  • @Mindslave You are a god! It worked! Thank you very much! Please do a normal answer so i can upvote and mark it as the selected answer! Commented Feb 2, 2021 at 15:06

1 Answer 1

Reset to default
1

The Problem here was the Curl command, not the Flask implementation, use -F to send a multipart/form-data request and the @ snytax to acctually send a file and not the filename as a String.

curl -X POST -F file=@/home/user1/Desktop/STEP_files/MyFile.txt 127.0.0.1:5000
Improve this answer
Sign up to request clarification or add additional context in comments.

Comments

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.