node.js - Angular HTTP 无法获得完整响应

Question

我尝试使用 Angular 8 中的 http post 请求获取完整请求。但是我无法从前端获得完整响应。是这样的，

{"classname": "2A"}

但我尝试使用 postman 检查后端。它给了我正确的响应，如下所示，

{
    "stuPosition": 2,
    "stuAverage": "80.0000",
    "classname": "2A"
}

这是我的 .ts 代码

async classStudentData() {
    const Studata = {
      term: this.DataForm1.value.term,
      classname: this.DataForm1.value.className,
      year: this.DataForm1.value.year,
      userid: this.userid
    };

    const url = 'http://localhost:3000/student_marks/studentAverage'

    this.http.post<any>(url, Studata).subscribe(res => {
      console.log(res)
    })
}

server.js 文件 当我从前端发送请求时，后端有 colsole.log() StuAverage，它是未定义。但 postman 请求并不是未定义的。

router.post("/studentAverage", function (req, res) {
    const year = req.body.year
    const term = req.body.term
    const userid = req.body.userid
    const classname = req.body.classname
    console.log(typeof(term))
    console.log(year + " " + term + " " + userid + " " + classname);

    var stuPosition;
    var stuAverage;
    var arr1 = new Array();
    mark.aggregate([
        {
            $match: { "year": year, "term": term, "classname": classname }
        },
        {
            $unwind: "$marks"
        },
        {
            $group: {
                _id: "$marks.userid",
                avg: { $avg: { $toInt: "$marks.mark" } },
            }
        }
    ])
        .sort({ _id: 1 })
        .exec()
        .then(function (resp) {
            var i = 0;
            for (i = 0; i < resp.length; i++) {
                arr1.push(resp[i])
            }

            var j = 0
            for (j = 0; j < arr1.length; j++) {
                if (arr1[j]._id == userid) {
                    stuPosition = j + 1
                    stuAverage = Math.floor(arr1[j].avg).toFixed(4)
                }
            }
            const avg = stuAverage
            console.log(avg)
            res.send({ 
                stuPosition: stuPosition,
                stuAverage: avg,
                classname: classname
            })
        });
})

Answer 1

这里我检查了后端请求值的数据类型，它们是数字和字符串，再次检查了postman请求，它们都是String类型。因此，我将代码中的所有值转换为字符串，如下所示。

    const year = req.body.year.toString()
    const term = req.body.term.toString()
    const userid = req.body.userid.toString()
    const classname = req.body.classname.toString()

现在代码可以正常工作了。感谢所有支持我的人。