Problem sending post request from Angular frontend to Flask backend

I am sending a file from front end to backend, i have also installed cors extension for the browser but got badly engaged with the error: I have tried a lot i performed debugging. I also added the cors in the flask, i added some code in the function of component.html to perform manual debugging. Previously i was receiving the error of cors disabled the response but it got resolved by adding cors in the browser:

App.py:

import csv
from flask import make_response, url_for
from flask import Flask, jsonify,render_template
from flask_cors import CORS, cross_origin
from werkzeug.utils import secure_filename
# from flask_restful import Resource, Api;
from flask import Flask, render_template, request, redirect
import matplotlib.pyplot as plt
from test import test
app = Flask(__name__)
#cors = CORS(app, resources={r"/api/http://localhost:4200": {"origins": "http://localhost:4200"}})# api = Api(app)
CORS(app, supports_credentials=True)
app.register_blueprint(test,url_prefix="/admin")

@app.route('/uploader', methods = ['POST','GET'])
#@cross_origin(["http://localhost:4200"])
@cross_origin(allow_headers=['http://localhost:4200'])
def upload_file():
    print(request.files)
    # check if the post request has the file part
    if 'file' not in request.files:
        print('no file in request')
        return"no file in request"
    file = request.files['file']
    if file.filename == '':
        print('no selected file')
        return"no selected file"
    if file and allowed_file(file.filename):
        print("hello")
        filename = secure_filename(file.filename)
        #file.save(os.path.join(app.config['UPLOAD_FOLDER'], filename))
        return "Successful"
    print("end")
    return"Bye"
@app.route('/')
def index():
    return  ('This is the main page of Python and calling the index function')

weather =  {
    "data":[ {
        "day":"1/6/2019",
        "temperature":"23",
        "windspeed":"16",
        "event":"Sunny"
    },  {
        "day":"5/6/2019",
        "temperature":"17",
        "windspeed":"18",
        "event":"Rainy"
    },  {
        "day":"6/6/2019",
        "temperature":"19",
        "windspeed":"21",
        "event":"Rainy"
    },  {
        "day":"7/6/2019",
        "temperature":"28",
        "windspeed":"14",
        "event":"Sunny"
    }
    ]
}

@app.route("/weatherReport/", methods = ['GET'])

def WeatherReport():
    global weather
    return jsonify([weather])
if __name__ == '__main__':
    app.run(debug = True)

component.ts:

  @ViewChild('fileInput') fileInput;
  ngOnInit() {
    this.todaydate = this.myservice.showTodayDate();
  }
  handleFileInput(files: FileList) {
    console.log('Inside handleFileInput');
    this.receivedFile = files.item(0);
    const isFileupload = true;
    console.log(` Received File: ${this.receivedFile}`);

  }

  uploadFile() {
    console.log('Inside  uploadFile');
    const files: FileList = this.fileInput.nativeElement.files;
    console.log('Inside  uploadFile line 02');
    if (files.length === 0) {
      console.log('Inside  uploadFile 03');
      console.log('no file content here');
      console.log('Inside  uploadFile 04');
      return;
    };
    console.log('Inside  uploadFile 05');

    this.restservice.parseTable(files).subscribe((data: any) => {
      console.log('Inside  uploadFile 06');
      console.log('Data that i am sending: ' + data);
    },  

//at here the error block is executing; (error) => { console.log(‘Inside uploadFile 07’); console.log(‘No Data Found’ + error); }); } } service.ts:

  parseTable(files) {
    const formData: FormData = new FormData();
    formData.append('file', files[0], files[0].name);
    return this.http.post(this.backendAddress, formData);
  }

component.html:

          <input #fileInput name="file" type="file"  (change)="handleFileInput($event.target.files)" >
<button mat-raised-button class="standard-button" (click)="uploadFile()">Upload file</button>

Error

*POST http://localhost:5000/uploader 500 (INTERNAL SERVER ERROR)*

Request:

*Please help me out friends*

[eric-wieser]

This is the bug tracker for numpy, not for general python help. Your code does not appear to use numpy at all. Perhaps your question would be more suited to StackOverflow.

Edit: It looks like @babaralishah already asked this on stackoverflow here: https://stackoverflow.com/questions/61479576/102441

[WarrenWeckesser]

It means, as far as we can tell, this is not the right place to ask your question. @eric-wieser noted that you also asked your question on StackOverlow. That is probably a good place to get help with your problem.