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javascript - 如何在 React Native 中对一组组件进行排序？

问题描述

我有一个嵌套映射来遍历我的数据，然后为我的数据中的每个对象返回一个反应组件。检查下面的代码：

return props.dataArray.map((classObj) => {
                    return classObj.timetable.map((timetableObj) => {
                        if (timetableObj.weekday === props.day) {
                            return ttCard({
                                lecturer: classObj.lecturer,
                                module: classObj.module,
                                room: classObj.room,
                                class_id: classObj.id,
                                timetable_id: timetableObj.id,
                                startTime: timetableObj.start_time,
                                endTime: timetableObj.end_time,
                                weekday: timetableObj.weekday
                            });
                        }
                        return null;
                    });
                });

我的问题是我的组件没有排序，它们必须排序，因为它是学生的时间表。查看下图，注意 10:30 AM 是我标签视图中的最新卡片：

在此处输入图像描述

到目前为止我尝试过的事情：

1-创建一个新数组，然后在if statement块之后对其进行排序-不工作 2-将排序后的数组返回到函数并将该数组映射以返回组件-不工作 3-循环并将对象作为组件参数中的函数返回：

ttCard( sortedArr.forEach((ttObject) => {
return ttObject
}))

也不工作

我已经用谷歌搜索并尝试进行研究，但到目前为止没有希望。我知道最初我的嵌套地图很糟糕，但这就是我的对象的样子：

[
    {
        "class_code": "English-5-G-2-L-1911-test-teacher",
        "id": 23,
        "lecturer": "test teacher",
        "module": "English-5",
        "room": "L",
        "timetable": [
            {
                "end_time": "9:00",
                "id": 37,
                "start_time": "8:00",
                "weekday": "Sunday"
            },
            {
                "end_time": "10:00",
                "id": 38,
                "start_time": "9:00",
                "weekday": "Sunday"
            },
            {
                "end_time": "10:00",
                "id": 47,
                "start_time": "9:00",
                "weekday": "Monday"
            },
            {
                "end_time": "10:00",
                "id": 48,
                "start_time": "9:00",
                "weekday": "Tuesday"
            },
            {
                "end_time": "11:30",
                "id": 52,
                "start_time": "10:30",
                "weekday": "Tuesday"
            },
            {
                "end_time": "11:30",
                "id": 54,
                "start_time": "10:30",
                "weekday": "Thursday"
            },
            {
                "end_time": "12:30",
                "id": 58,
                "start_time": "11:30",
                "weekday": "Thursday"
            },
            {
                "end_time": "14:00",
                "id": 61,
                "start_time": "13:00",
                "weekday": "Wednesday"
            }
        ]
    }
]

标签： javascriptarraysreactjsreact-native

解决方案

您可以sort在输出中使用 startTime 来排列数组

.sort((a, b) => {
    // These lines are so we can directly compare the times
    // I would recommend to send timestamps down with your data (if possible)
    var aTime = a.startTime.replace(':', '');
    var bTime = b.startTime.replace(':', '');

    // Sort by smallest first
    return aTime - bTime;
  });

我还建议过滤掉数组中的空值

使用您的示例- 

var classesArr = props.dataArray.map((classObj) => {
  return classObj.timetable.map((timetableObj) => {
    if (timetableObj.weekday === props.day) {
      return {
        lecturer: classObj.lecturer,
        module: classObj.module,
        room: classObj.room,
        class_id: classObj.id,
        timetable_id: timetableObj.id,
        startTime: timetableObj.start_time,
        endTime: timetableObj.end_time,
        weekday: timetableObj.weekday
      }
    }
    return null;
  }).filter(x => x); // Filter out any null values
}).filter(x => x); // Filter out any null values.

// Flatten array so it is sortable/mapable
return [].concat.apply([], classesArr).sort((a, b) => {
  // These lines are so we can directly compare the times
  // I would recommend to send timestamps down with your data (if possible)
  var aTime = a.startTime.replace(':', '');
  var bTime = b.startTime.replace(':', '');
  // Sort by smallest time first
  return aTime - bTime;
}).map((x) => {
  return ttCard(x);
})

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