从 Json 数据创建复杂表

Question

我有一个看起来像这样的 JSON

[
{
    "teacher": "teacher1",
    "student": "student1"
    },
{
   "teacher": "teacher1",
    "student": "student1"
    },
{
    "teacher": "teacher1",
    "student": "student1"
    },
{
    "teacher": "teacher2",
    "student": "student1"
    },
{
   "teacher": "teacher2",
    "student": "student2"
    }
]

我想将它转换成这样的方式，它可以向我显示每个老师的计数

[
    {
        "teacherName": "teacher1",
        "teacherCount": "3"
    },
    {
        "teacherName": "teacher2",
        "teacherCount": "2"
    },
]

我正在开发一个节点项目，我需要在表格中打印这些数据。

Answer 1

您可以构建一个 Map（使用 .reduce .reduce() ），它由teacher值索引/键控。 存储在teacher 中的值是在您的对象数组中看到teacher 的次数的计数。 然后，您可以将Array.from()与使用 reduce 构建的Map使用，以从 map 获取每个键值对（其中键是teacherName，值是teacherCount）。 要获取每个键值对，您可以使用 Array.from() 和 map 每个键值 ([key, value]) 到 object 的映射 function ，例如：

 const data = [{ "teacher": "teacher1", "student": "student1" }, { "teacher": "teacher1", "student": "student1" }, { "teacher": "teacher1", "student": "student1" }, { "teacher": "teacher2", "student": "student1" }, { "teacher": "teacher2", "student": "student2" } ]; const res = Array.from(data.reduce((map, {teacher}) => { return map.set(teacher, (map.get(teacher) || 0) + 1); }, new Map), ([teacherName, teacherCount]) => ({teacherName, teacherCount})); console.log(res);

Answer 2

您可以使用reduce将您的计数收集到一个唯一的集合中，如果教师存在则将其递增，否则将其初始化为 1。然后使用map来说明如何格式化的示例。

 let data = getData(); let teachers = data.reduce((acc, val) => { if (val.teacher in acc) acc[val.teacher]++; else acc[val.teacher] = 1; return acc; }, {}); let formatted = Object.entries(teachers).map( ([teacherName, teacherCount]) => ({ teacherName, teacherCount }) ); console.log(formatted); /*****************************************************************/ function getData() { return [{ "teacher": "teacher1", "student": "student1" }, { "teacher": "teacher1", "student": "student1" }, { "teacher": "teacher1", "student": "student1" }, { "teacher": "teacher2", "student": "student1" }, { "teacher": "teacher2", "student": "student2" } ] }