如何使用 Flatten 将嵌套 JSON 转换为 CSV？

Question

我正在尝试使用 exceljs 库将 JSON 数据导出到 csv/excel。我的数据有嵌套对象，我想将嵌套对象转换为列。

我有这个 JSON 数据

[
  {
    "name": "Raghav",
    "grade": "I",
    "marks": [
      {
        "subject": "Maths",
        "grade": "A1"
      },
      {
        "subject": "Science",
        "marks": "B"
      }
    ]
  },
  {
    "name": "Isha",
    "grade": "II",
    "marks": [
      {
        "subject": "Maths",
        "grade": "B1"
      },
      {
        "subject": "Science",
        "marks": "A"
      }
    ]
  }
]

这是将 JSON 数据导出到 csv 的代码

const ExcelJS = require('exceljs');

// excel export start
let workbook = new ExcelJS.Workbook()
let worksheet = workbook.addWorksheet('marks')
worksheet.columns = [

    { header: 'Name', key: 'name' },
    { header: 'Surname', key: 'surname' },
    { header: 'Marks', key: 'marks' },
]

worksheet.getRow(1).font = { bold: true }

async function exportToExcel() {

    console.log('exportToExcel called');
    let queryExport = query(collectionGroup(db, "2023-24"),
        where('year', '==', '2023-24'),
        where('section', '==', 'SSSV GSEB Primary (EM)'),
        where('grade', '==', '8'),
        where('division', '==', 'B'),
        where('exam', '==', 'FA01'),
        orderBy('roll', "asc"),
        limit(2)
    );

// getting data from Firestore
    getDocs(queryExport)
        .then((snapshot) => {
            snapshot.forEach((doc, index) => {
                const rowIndex = index + 2
                let e = doc.data()
                console.log(e);
                let newEntry = doc.data();
                newEntry.name = e.name;
                newEntry.surname = e.surname;

                worksheet.columns.forEach(column => {
                    worksheet.addRow({
                        ...e,
                    })
                })
            });
            workbook.xlsx.writeBuffer()
                .then(buffer => FileSaver.saveAs(new Blob([buffer]), `pcs_bkp_${Date.now()}.xlsx`))
                .catch(err => console.log('Error writing excel export', err))
        });
}

上面的代码工作正常，我得到的 csv 文件如下所示。

但我想导出我的嵌套数组转换，预期结果应如下所示。

请帮我解决一下。

Answer 1

您的数据对象（不是 JSON 字符串，而是一个对象）包含奇怪格式的标记：对于主题“数学”，它们位于键“等级”下，对于“科学”，它们存储在“标记”下。

下面的代码片段可以处理它，但这只是演示 CSV 转换的初步尝试，因为一旦任何数据字符串中包含逗号，它就会中断。

const data=[{"name":"Raghav","grade":"I","marks":[{"subject":"Maths","grade":"A1"},{"subject":"Science","marks":"B"}]},{"name":"Isha","grade":"II","marks":[{"subject":"Maths","grade":"B1"},{"subject":"Science","marks":"A"}]}];


const csv=["Name","Grade",data[0].marks.map(m=>m.subject)].join(",")+"\n"
 +data.map((d,i)=>[d.name,d.grade,...d.marks.map(m=>m.grade||m.marks)].join(",")
).join("\n");

console.log(csv);