Flask Ajax在上传时返回POST HTTP / 1.1“400错误

Question

大家好我有一个简单的表单，上面有这样的上传按钮。

<form role="form" id="sf" name = "sf" method="post" 
  enctype="multipart/form-data" action="javascript:void();">
<input type="file" id="file" name="file" class="file">
</form>

我的js看起来像这样。

$('#file').bind('change', function() {
        var form_data = new FormData($('#suject-form')[15]);

        var request = $.ajax({
         url: "/upload",
         type: "POST",
         contentType: "application/json",
         cache: false,
         processData: false,
         async: false,
         data: {
      file: new FormData($('#suject-form')[0]), 
      state: 'testing'
    },  
    dataType: "json",
  })
         .done(function(data){
          console.log(data);

        })
return false;
});

- 当我尝试获取文件数据时，它一直给我400错误，

-

@app.route('/upload', methods=['POST'])
def upload():

    if request.method == 'POST':
        state= request.form['state']
        files = request.files['file']
        # if I leave out file it returns but fails when leave in files


    return jsonify(result=[state])

任何人都知道我做错了什么？谢谢！