如何使用lodash从对象中删除空值

Question

我有一个具有多个属性的对象,我想使用lodash删除空的对象/嵌套对象.做这个的最好方式是什么？

Let template = {
      node: "test",
      representation: {
        range: { }
      },
      transmit: {
        timeMs: 0
      }
    };

至

template = {
      node: "test",
      transmit: {
        timeMs: 0
      }
    };

我试过这样的事,但我迷路了.

Utils.removeEmptyObjects = function(obj) {
  return _.transform(obj, function(o, v, k) {
    if (typeof v === 'object') {
      o[k] = _.removeEmptyObjects(v);
    } else if (!_.isEmpty(v)) {
      o[k] = v;
    }
  });
};
_.mixin({
  'removeEmptyObjects': Utils.removeEmptyObjects
});

Answer 1

从没有嵌套对象的对象中删除未定义、null 和空字符串

_.omitBy(object, (v) => _.isUndefined(v) || _.isNull(v) || v === '');

对于嵌套对象，您可以创建一个递归函数来执行此操作

它将删除任何级别的空对象、空数组、null、未定义、空字符串......

removeEmpty(obj) {
        let finalObj = {};
        Object.keys(obj).forEach((key) => {
            if (obj[key] && typeof obj[key] === 'object') {
                const nestedObj = removeEmpty(obj[key]);
                if (Object.keys(nestedObj).length) {
                    finalObj[key] = nestedObj;
                }
            } else if (obj[key] !== '' && obj[key] !== undefined && obj[key] !== null) {
                finalObj[key] = obj[key];
            }
        });
        return finalObj;
    }

更新 11-4-2022

根据@RahulSoni 评论，我刚刚修复了数组到对象的转换。现在一切都该处理了。如果您还有其他意见，请告诉我

removeEmpty(obj) {
    const finalObj = {};
    Object.keys(obj).forEach((key) => {
      if (obj[key] && typeof obj[key] === 'object' && !Array.isArray(obj[key])) {
        const nestedObj = this.removeEmpty(obj[key]);
        if (Object.keys(nestedObj).length) {
          finalObj[key] = nestedObj;
        }
      } else if (Array.isArray(obj[key])) {
        if (obj[key].length) {
          obj[key].forEach((x) => {
            const nestedObj = this.removeEmpty(x);
            if (Object.keys(nestedObj).length) {
              finalObj[key] = finalObj[key] ? [...finalObj[key], nestedObj] : [nestedObj];
            }
          });
        }
      } else if (obj[key] !== '' && obj[key] !== undefined && obj[key] !== null) {
        finalObj[key] = obj[key];
      }
    });
    return finalObj;
  }

例子：

   const obj = {
            a: '',
            aa: null,
            aaa: undefined,
            aaaa: 'aaaa',
            aaaaa: 0,
            aaaaaa: 1,
            aaaaaaa: 2,
            aaaaaaaa: true,
            aaaaaaaaa: false,
            emptyObj: {},
            emptyArray: [],
            array: [
                {
                    a: '',
                    aa: null,
                    aaa: undefined,
                    aaaa: 'aaaa',
                    aaaaa: 0,
                    aaaaaa: 1,
                    aaaaaaa: 2,
                    aaaaaaaa: true,
                    aaaaaaaaa: false,
                    emptyObj: {},
                    emptyArray: [],
                    obj: {
                        a: '',
                        aa: null,
                        aaa: undefined,
                        aaaa: 'aaaa',
                        aaaaa: 0,
                        aaaaaa: 1,
                        aaaaaaa: 2,
                        aaaaaaaa: true,
                        aaaaaaaaa: false,
                        emptyObj: {},
                        emptyArray: [],
                    },
                },
                {
                    a: '',
                    aa: null,
                    aaa: undefined,
                    aaaa: 'aaaa',
                    aaaaa: 0,
                    aaaaaa: 1,
                    aaaaaaa: 2,
                    aaaaaaaa: true,
                    aaaaaaaaa: false,
                    emptyObj: {},
                    emptyArray: [],
                    obj: {
                        a: '',
                        aa: null,
                        aaa: undefined,
                        aaaa: 'aaaa',
                        aaaaa: 0,
                        aaaaaa: 1,
                        aaaaaaa: 2,
                        aaaaaaaa: true,
                        aaaaaaaaa: false,
                        emptyObj: {},
                        emptyArray: [],
                    },
                },
            ],
            b: {
                a: '',
                aa: null,
                aaa: undefined,
                aaaa: 'aaaa',
                aaaaa: 0,
                aaaaaa: 1,
                aaaaaaa: 2,
                aaaaaaaa: true,
                aaaaaaaaa: false,
                emptyObj: {},
                emptyArray: [],
                c: {
                    a: '',
                    aa: null,
                    aaa: undefined,
                    aaaa: 'aaaa',
                    aaaaa: 0,
                    aaaaaa: 1,
                    aaaaaaa: 2,
                    aaaaaaaa: true,
                    aaaaaaaaa: false,
                    emptyObj: {},
                    emptyArray: [],
                },
            },
        };

        const finalObj = removeEmpty(obj);
        console.log('finalObj After remove', finalObj);

Answer 2

您可以通过几个步骤实现此目的:

1. 使用pickBy()使用isObject()谓词选择对象键值.

2. 使用mapValues()以递归方式调用removeEmptyObjects(),请注意它只会使用对象调用此函数.

3. mapValues()使用带有isEmpty()谓词的omitBy()删除所有找到的空对象.

4. 使用assign()进行赋值,并omitBy()使用isObject()谓词重新分配对象中的所有原始值.

function removeEmptyObjects(obj) {
  return _(obj)
    .pickBy(_.isObject) // pick objects only
    .mapValues(removeEmptyObjects) // call only for object values
    .omitBy(_.isEmpty) // remove all empty objects
    .assign(_.omitBy(obj, _.isObject)) // assign back primitive values
    .value();
}

function removeEmptyObjects(obj) {
  return _(obj)
    .pickBy(_.isObject)
    .mapValues(removeEmptyObjects)
    .omitBy(_.isEmpty)
    .assign(_.omitBy(obj, _.isObject))
    .value();
}

_.mixin({
  removeEmptyObjects: removeEmptyObjects
});

var template = {
  node: "test",
  representation: {
    range: {}
  },
  transmit: {
    timeMs: 0
  }
};

var result = _.removeEmptyObjects(template);

document.write('<pre>' + JSON.stringify(result, 0, 4) + '</pre>');

<script src="https://cdn.jsdelivr.net/lodash/4.13.1/lodash.min.js"></script>