如何仅转换嵌套对象中的2个属性，其余属性保持不变？

你可以通过以下两种方式简化代码，无需手动枚举所有不需要转换的字段：

方法一：修改原对象的指定属性（推荐） #

直接基于原数据结构修改需要处理的字段，利用json2csv的路径解析能力自动提取其余字段：

const { Parser: Json2csvParser } = require('json2csv');

const json2csvFields = [
  { value: 'root.filename', label: 'File Name' },
  { value: 'issue.root.priority', label: 'Priority' },
  { value: 'issue.root.url', label: 'URL' },
  { value: 'issue.root.startline', label: 'Start Line' },
  { value: 'issue.root.stopline', label: 'Stop Line' },
  { value: 'issue.root.startcolumn', label: 'Start Column' },
  { value: 'issue.root.stopcolumn', label: 'Stop Column' },
  { value: 'issue.root.issuename', label: 'Issue Name' },
  { value: 'issue.root.issuecategory', label: 'Issue Category' },
  { value: 'issue._', label: 'Issue Description' },
];

const sampleData = [
  {
    root: {
      filename: '/home/users/john-doe/workspace/foo-project/src/main/classes/foo.cls',
    },
    issue: {
      root: {
        priority: 1,
        url: 'www.example.com',
        startline: 100,
        stopline: 105,
        startcolumn: 20,
        stopcolumn: 25,
        issuename: 'blah',
        issuecategory: 'Category A',
      },
      _: '     Fox     ',
    },
  },
];

// 深拷贝原数据，避免修改原始输入
const deepClone = (obj) => JSON.parse(JSON.stringify(obj));

const json2csvOptions = {
  fields: json2csvFields,
  quote: '',
  header: true,
  transforms: [
    (item) => {
      const newItem = deepClone(item);
      // 处理文件名截断
      newItem.root.filename = newItem.root.filename.replace(
        '/home/users/john-doe/workspace/foo-project/src/main/classes/',
        ''
      );
      // 处理描述字段的修剪和引号包裹
      newItem.issue._ = `"${newItem.issue._.trim()}"`;
      return newItem;
    },
  ],
};

const json2csvParser = new Json2csvParser(json2csvOptions);
const csv = json2csvParser.parse(sampleData);
console.log(csv);

说明： #

1. 用deepClone深拷贝原数据，避免污染原始输入
2. 仅对需要转换的两个字段做针对性修改，其余字段保持原结构
3. 依靠json2csv的路径解析能力（fields中的value为点路径），自动提取其余字段的值，无需手动枚举

方法二：基于字段列表动态生成转换结果 #

遍历字段列表，只对目标字段做转换，其余字段通过路径提取：

const { Parser: Json2csvParser } = require('json2csv');

const json2csvFields = [
  { value: 'root.filename', label: 'File Name' },
  { value: 'issue.root.priority', label: 'Priority' },
  { value: 'issue.root.url', label: 'URL' },
  { value: 'issue.root.startline', label: 'Start Line' },
  { value: 'issue.root.stopline', label: 'Stop Line' },
  { value: 'issue.root.startcolumn', label: 'Start Column' },
  { value: 'issue.root.stopcolumn', label: 'Stop Column' },
  { value: 'issue.root.issuename', label: 'Issue Name' },
  { value: 'issue.root.issuecategory', label: 'Issue Category' },
  { value: 'issue._', label: 'Issue Description' },
];

const sampleData = [
  {
    root: {
      filename: '/home/users/john-doe/workspace/foo-project/src/main/classes/foo.cls',
    },
    issue: {
      root: {
        priority: 1,
        url: 'www.example.com',
        startline: 100,
        stopline: 105,
        startcolumn: 20,
        stopcolumn: 25,
        issuename: 'blah',
        issuecategory: 'Category A',
      },
      _: '     Fox     ',
    },
  },
];

// 根据点路径获取嵌套对象的值
const getNestedValue = (obj, path) => {
  return path.split('.').reduce((current, key) => current?.[key], obj);
};

const json2csvOptions = {
  fields: json2csvFields,
  quote: '',
  header: true,
  transforms: [
    (item) => {
      const transformed = {};
      json2csvFields.forEach(({ value: fieldPath }) => {
        if (fieldPath === 'root.filename') {
          transformed[fieldPath] = item.root.filename.replace(
            '/home/users/john-doe/workspace/foo-project/src/main/classes/',
            ''
          );
        } else if (fieldPath === 'issue._') {
          transformed[fieldPath] = `"${item.issue._.trim()}"`;
        } else {
          transformed[fieldPath] = getNestedValue(item, fieldPath);
        }
      });
      return transformed;
    },
  ],
};

const json2csvParser = new Json2csvParser(json2csvOptions);
const csv = json2csvParser.parse(sampleData);
console.log(csv);

说明： #

1. 自定义getNestedValue函数，实现从嵌套对象中按点路径提取值
2. 遍历字段列表，仅对需要转换的字段做特殊处理，其余字段自动提取
3. 适合字段数量较多或需要动态调整字段的场景

两种方法都能输出与原代码完全一致的结果，且彻底消除了冗余的字段枚举。

内容的提问来源于stack exchange，提问作者javanoob