Python Flask，上传文件-引发BuildError（端点，值，方法）

Question

I followed this tutorial for uploading files to a webserver via Flask, with the notable exception of the return part.

My intention is to upload pictures.

Here's my code:

from flask import Flask, request, jsonify, json, Blueprint, redirect, url_for, send_from_directory
from werkzeug import secure_filename

app = Flask(__name__)

allowed_extensions = set(['png', 'jpg', 'jpeg', 'gif', 'bmp'])
folder_upload = '/Users/myusername/Documents/Project_Upload/'

@CustomersAPI.route('/customers/addpicture', methods=['POST'])
def add_picture():
    file = request.files['value']
    print file.filename
    if file and allowed_file(file.filename):
        filename = secure_filename(file.filename)
        file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))
        #return redirect(url_for('uploaded_file', filename=filename))
        return str(url_for('uploaded_file', filename=filename))

    return "Unable to upload."

def allowed_file(filename):
    return '.' in filename and filename.rsplit('.', 1)[1] in allowed_extensions

if __name__ == '__main__':
    app.config['UPLOAD FOLDER'] = folder_upload
    app.run(host = '0.0.0.0', debug=True)

As I do not have the HTML files yet (hence the commented out return redirect ), I use CocoaRestClient for testing, and here are the parameters I used:

Everything okay so far, until I hit the Submit button. Then, the following error appears:

Traceback (most recent call last):
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1836, in __call__
    return self.wsgi_app(environ, start_response)
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1820, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1403, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1817, in wsgi_app
    response = self.full_dispatch_request()
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1477, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1381, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1475, in full_dispatch_request
    rv = self.dispatch_request()
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1461, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/Users/myusername/Documents/Project_Omnimoda/API/main.py", line 192, in add_picture
    return redirect(url_for('uploaded_file', filename=filename))
  File "/Library/Python/2.7/site-packages/flask/helpers.py", line 312, in url_for
    return appctx.app.handle_url_build_error(error, endpoint, values)
  File "/Library/Python/2.7/site-packages/flask/app.py", line 1641, in handle_url_build_error
    reraise(exc_type, exc_value, tb)
  File "/Library/Python/2.7/site-packages/flask/helpers.py", line 305, in url_for
    force_external=external)
  File "/Library/Python/2.7/site-packages/werkzeug/routing.py", line 1649, in build
    raise BuildError(endpoint, values, method)
BuildError: ('uploaded_file', MultiDict([('filename', '3611571-dc_holiday.jpg')]), None)

Funny thing is, the image '3611571-dc_holiday.jpg' actually did get copied from my Downloads folder to the Project_Upload folder, so it worked, there's just an error that I'm not sure how to solve.

Any ideas? Thanks.

Answer 1

You haven't defined the uploaded_file endpoint. You need to do that.

@CustomersAPI.route('/customers/SOMETHINGOGESTHERE')
def uploaded_file(filename):
    # Do something here with the file, like return it.
    return send_from_directory(
        folder_upload, filename, as_attachment=True)