通过ajax获取后台数据，更新datatable，报错“DataTables warning: table id=datatable - Invalid JSON response. ”

Question

问题遇到的现象和发生背景

通过ajax获取后台数据，更新datatable，报错“DataTables warning: table id=datatable - Invalid JSON response. ”

问题相关代码，请勿粘贴截图

flask代码：

@app.route('/result', methods = ['POST', 'GET'])
def route1():

    # 获取表单
    form = request.form

    # 设置数据库
    connStr = r'Driver={Microsoft Access Driver (*.mdb)};DBQ=C:\Users\hp\Desktop\colloge choosing\colloge_info.accdb'
    conn = pypyodbc.win_connect_mdb(connStr)
    cur = conn.cursor()
    # 设置sql
    loc = ' 所在省 = \'' + form['loc'] + '\''



    sql_order = 'select * from 普通文理 where' + loc + ';'
    cur.execute(sql_order)
    sql_result = cur.fetchall()
    num = len(sql_result)
    length = len(sql_result[0])
    # print(sql_result[0])
    # print(num, length)
    # result_json = []
    # keys = ['序号', '首选科目', '院校代号', '院校名称', '办学性质', '所在省', '门类', '专业类', '专业代号', '专业名称', '专业备注', '院校备注', '21计划', '21剩余', '22计划', '学制', '学费', '再选科目', '投档最低分', '分段人数', '最低位次', '语数成绩', '语数最高成绩', '外语成绩', '首选科目成绩', '再选科目最高成绩', '再选科目次高成绩', '志愿号']
    # for item in sql_result:
    #     result_json.append(dict(zip(keys, item)))


    return jsonify({"result" : sql_result, "num": num, "length" : length})

js部分

    <script type="text/javascript">
      $("#TabChange").click(function(){
        $.ajax({
          type: 'POST',
          url:  'result',
          data: new FormData(document.getElementById("uploadForm")),
          dataType: "json",
          async: false,  
          cache: false,  
          contentType: false,  
          processData: false,
          success: function(data){
            $("#lintresult").html("1231321321");
            $("#datatable").dataTable({
              processing: true,
              serverSide: true, //开启后端模式
              destroy:true,
              ajax:data,
              columns: [
                {"result":"序号"},
                {"result":"首选科目"},
                {"result":"院校代号"},
                {"result":"院校名称"},
                {"result":"办学性质"},
                {"result":"所在省"},
                {"result":"门类"},
                {"result":"专业类"},
                {"result":"专业代号"},
                {"result":"专业名称"},
                {"result":"专业备注"},
                {"result":"院校备注"},
                {"result":"21计划"},
                {"result":"21剩余"},
                {"result":"22计划"},
                {"result":"学制"},
                {"result":"学费"},
                {"result":"再选科目"},
                {"result":"投档最低分"},
                {"result":"分段人数"},
                {"result":"最低位次"},
                {"result":"语数成绩"},
                {"result":"语数最高成绩"},
                {"result":"外语成绩"},
                {"result":"首选科目成绩"},
                {"result":"再选科目最高成绩"},
                {"result":"再选科目次高成绩"},
                {"result":"志愿号"}
                ],

              paging: true,//开启分页
              ordering: true,//开启排序
              searching: true,//开启搜索
              iDisplayLength : 50,//默认长度
              });
          }
        })
      })
    </script>

后台获取的数据

{
  "length": 28, 
  "num": 4707, 
  "result": [
    [
      117.0, 
      "物理本科", 
      "0169", 
      "鞍山师范学院", 
      "公办", 
      "辽宁省", 
      "文学", 
      "外国语言文学类", 
      "38", 
      "日语", 
      "(外语语种：英语或日语)", 
      null, 
      2.0, 
      null, 
      null, 
      "四年", 
      "4800", 
      "不限", 
      486.0, 
      396.0, 
      49378.0, 
      192.0, 
      99.0, 
      116.0, 
      36.0, 
      72.0, 
      70.0, 
      38.0
    ], 
    [
      118.0, 
      "物理本科", 
      "0169", 
      "鞍山师范学院", 
      "公办", 
      "辽宁省", 
      "文学", 
      "外国语言文学类", 
      "39", 
      "西班牙语", 
      null, 
      null, 
      2.0, 
      null, 
      null, 
      "四年", 
      "4800", 
      "不限", 
      480.0, 
      376.0, 
      51763.0, 
      189.0, 
      113.0, 
      133.0, 
      28.0, 
      67.0, 
      63.0, 
      28.0
    ], 
    [
      119.0, 
      "物理本科", 
      "0169", 
      "鞍山师范学院", 
      "公办", 
      "辽宁省", 
      "管理学", 
      "工商管理类", 
      "40", 
      "会计学", 
      null, 
      null, 
      5.0, 
      null, 
      null, 
      "四年", 
      "5200", 
      "不限", 
      501.0, 
      400.0, 
      43440.0, 
      196.0, 
      99.0, 
      117.0, 
      56.0, 
      70.0, 
      62.0, 
      8.0
    ]
]
}

Answer 1

你这个应该是请求的url有问题，导致没有查询到结果，系统直接返回的是报错码不是json,所以就出现这种情况。
可以尝试下面的修改思路。
1- 把请求的url换成绝对路径

url:  '/result',

2- 如果换成绝对路径不行，你再单独请求一下这个/result这个路径，测试一下返回的结果是否正常。

另外,建议把error函数也添加上，出现error时可以进行异常提醒。