Bad request 400 when sending file to flask server by ajax

I am trying to send a file by browser to flask server. But don't know the reason why my flask server return 400 bad request error.

I used ajax to send a file sendform.html

<!DOCTYPE html>
<script src="https://code.jquery.com/jquery-3.4.1.min.js"></script>
<script type=text/javascript src="{{url_for('static', filename='jQuery.js') }}"></script>

<script>
   
   function fn_submit(){
    var form = new FormData();
   form.append("file1",$("#file1")[0].files[0]);
   jQuery.ajax({
    url : "http:127.0.0.1/request",
    type : "POST",
    processData : false,
    contentType : false,
    data : form,
    success:function(response){
        alert("success");
        console.log(response);
    },
    error: function(jqXHR){
        alert(jqXHR.responseText);
    }
   });
   }


</script>


<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div>
        <label for="file1">파일</label> 
        <input type="file" id="file1" name="file1"> 
        <button id="btn_submit" onclick="javascript:fn_submit()">전송</button>    
    </div>
</body>
</html>

flaskServer.py

from flask import Flask, request, jsonify, Blueprint
from flask_wtf.csrf import CSRFProtect
from werkzeug.utils import secure_filename
import os
SECRET_KEY = os.urandom(32)

app = Flask(__name__)
app.config['SECRET_KEY'] = SECRET_KEY

@app.route('/request', methods =['POST'])
def query():
    f = request.files['file']
    print('f ok')
    f.save('C:/Users/Tonykrjhc/Desktop/' + secure_filename('dasd.png'))
    return 'done!'

app.run(host="192.168.35.17",port=8227)

cannot solve this problem. and cannot found out specific reason why it makes 400 error. How to makes it work properly?

Bad request 400 when sending file to flask server by ajax

0 Answers