我有两个对象:oldObj和newObj。
oldObj中的数据用于填充表单，而newObj是用户更改该表单中的数据并提交的结果。
这两个物体都很深。它们具有对象或对象数组等属性-它们可以有n层深，因此diff算法需要递归。
现在我不仅需要弄清楚从oldObj到newObj更改了什么(如添加/更新/删除)，而且还需要知道如何最好地表示它。
到目前为止，我的想法只是构建一个通用的deepdiffbetweenobjects方法，该方法将返回窗体上的对象{add:{…}，upd:{…}，del:{…但我转念一想:以前一定有人需要它。
所以…有没有人知道一个库或一段代码可以做到这一点，并且可能有更好的方式来表示差异(以一种仍然是JSON可序列化的方式)?
更新:
我想到了一个更好的方法来表示更新的数据，通过使用与newObj相同的对象结构，但将所有属性值转换为窗体上的对象:
{type: '<update|create|delete>', data: <propertyValue>}
如果newObj。prop1 = 'new value'和oldObj。prop1 = 'old value'它将设置returnbj。Prop1 = {type: 'update'， data: 'new value'}
更新2:
当我们处理数组的属性时，它会变得非常麻烦，因为数组[1,2,3]应该被计算为等于[2,3,1]，这对于基于值的类型的数组(如string, int和bool)来说足够简单，但是当涉及到引用类型的数组(如对象和数组)时就很难处理了。
数组的示例应该是相等的:
[1,[{c: 1},2,3],{a:'hey'}] and [{a:'hey'},1,[3,{c: 1},2]]
不仅要检查这种类型的深度值相等相当复杂，而且要找出一种表示可能发生的变化的好方法。
使用下划线，一个简单的差异:
var o1 = {a: 1, b: 2, c: 2},
o2 = {a: 2, b: 1, c: 2};
_.omit(o1, function(v,k) { return o2[k] === v; })
o1中对应但o2值不同的部分的结果:
{a: 1, b: 2}
如果是深差的话就不一样了
function diff(a,b) {
var r = {};
_.each(a, function(v,k) {
if(b[k] === v) return;
// but what if it returns an empty object? still attach?
r[k] = _.isObject(v)
? _.diff(v, b[k])
: v
;
});
return r;
}
正如@Juhana在评论中指出的那样，上面只是一个diff a- >b，并且不可逆(这意味着b中的额外属性将被忽略)。用a——>b——>a代替:
(function(_) {
function deepDiff(a, b, r) {
_.each(a, function(v, k) {
// already checked this or equal...
if (r.hasOwnProperty(k) || b[k] === v) return;
// but what if it returns an empty object? still attach?
r[k] = _.isObject(v) ? _.diff(v, b[k]) : v;
});
}
/* the function */
_.mixin({
diff: function(a, b) {
var r = {};
deepDiff(a, b, r);
deepDiff(b, a, r);
return r;
}
});
})(_.noConflict());
完整的示例+tests+mixins请参见http://jsfiddle.net/drzaus/9g5qoxwj/
我采用@sbgoran上面的答案，并根据我的情况修改了它，以将数组视为集合(即顺序对于diff不重要)
const deepDiffMapper = function () {
return {
VALUE_CREATED: "created",
VALUE_UPDATED: "updated",
VALUE_DELETED: "deleted",
VALUE_UNCHANGED: "unchanged",
map: function(obj1: any, obj2: any) {
if (this.isFunction(obj1) || this.isFunction(obj2)) {
throw "Invalid argument. Function given, object expected.";
}
if (this.isValue(obj1) || this.isValue(obj2)) {
return {
type: this.compareValues(obj1, obj2),
data: obj2 === undefined ? obj1 : obj2
};
}
if (this.isArray(obj1) || this.isArray(obj2)) {
return {
type: this.compareArrays(obj1, obj2),
data: this.getArrayDiffData(obj1, obj2)
};
}
const diff: any = {};
for (const key in obj1) {
if (this.isFunction(obj1[key])) {
continue;
}
let value2 = undefined;
if (obj2[key] !== undefined) {
value2 = obj2[key];
}
diff[key] = this.map(obj1[key], value2);
}
for (const key in obj2) {
if (this.isFunction(obj2[key]) || diff[key] !== undefined) {
continue;
}
diff[key] = this.map(undefined, obj2[key]);
}
return diff;
},
getArrayDiffData: function(arr1: Array<any>, arr2: Array<any>) {
const set1 = new Set(arr1);
const set2 = new Set(arr2);
if (arr1 === undefined || arr2 === undefined) {
return arr1 === undefined ? arr1 : arr2;
}
const deleted = [...arr1].filter(x => !set2.has(x));
const added = [...arr2].filter(x => !set1.has(x));
return {
added, deleted
};
},
compareArrays: function(arr1: Array<any>, arr2: Array<any>) {
const set1 = new Set(arr1);
const set2 = new Set(arr2);
if (_.isEqual(_.sortBy(arr1), _.sortBy(arr2))) {
return this.VALUE_UNCHANGED;
}
if (arr1 === undefined) {
return this.VALUE_CREATED;
}
if (arr2 === undefined) {
return this.VALUE_DELETED;
}
return this.VALUE_UPDATED;
},
compareValues: function (value1: any, value2: any) {
if (value1 === value2) {
return this.VALUE_UNCHANGED;
}
if (this.isDate(value1) && this.isDate(value2) && value1.getTime() === value2.getTime()) {
return this.VALUE_UNCHANGED;
}
if (value1 === undefined) {
return this.VALUE_CREATED;
}
if (value2 === undefined) {
return this.VALUE_DELETED;
}
return this.VALUE_UPDATED;
},
isFunction: function (x: any) {
return Object.prototype.toString.call(x) === "[object Function]";
},
isArray: function (x: any) {
return Object.prototype.toString.call(x) === "[object Array]";
},
isDate: function (x: any) {
return Object.prototype.toString.call(x) === "[object Date]";
},
isObject: function (x: any) {
return Object.prototype.toString.call(x) === "[object Object]";
},
isValue: function (x: any) {
return !this.isObject(x) && !this.isArray(x);
}
};
}();
2022年更新:
我想出了一个非常简单的算法来解决大多数边缘情况:
使物体变平
简单地比较两个扁平对象并创建一个扁平的diff对象
平展diff对象
如果你保存了被压平的物体，你就可以重复使用它，并在你真正需要的时候进行“反压平…”
let oldObject = {var1:'value1', var2:{ var1:'value1', var2:'value2'},var3:'value3'};
let newObject = {var2:{ var1:'value11', var3:'value3'},var3:'value3'};
let flatOldObject = flattenObject(oldObject)
/*
{
'var1':'value1',
'var2.var1':'value1',
'var2.var2':'value2',
'var3':'value3'
}
*/
let flatNewObject = flattenObject(newObject)
/*
{
'var2.var1':'value11',
'var2.var3':'value3',
'var3':'value3'
}
*/
let flatDiff = diffFlatten(flatOldObject, flatNewObject)
let [updated,removed] = flatDiff
/*
updated = {
'var2.var1':'value11',
'var2.var3':'value3'
}
removed = {
'var1':'value1'
}
*/
当然，您可以为这些步骤提供您的实现。但我的想法是:
实现
function flattenObject(obj) {
const object = Object.create(null);
const path = [];
const isObject = (value) => Object(value) === value;
function dig(obj) {
for (let [key, value] of Object.entries(obj)) {
path.push(key);
if (isObject(value)) dig(value);
else object[path.join('.')] = value;
path.pop();
}
}
dig(obj);
return object;
}
function diffFlatten(oldFlat, newFlat) {
const updated = Object.assign({}, oldFlat);
const removed = Object.assign({}, newFlat);
/**delete the unUpdated keys*/
for (let key in newFlat) {
if (newFlat[key] === oldFlat[key]) {
delete updated[key];
delete removed[key];
}
}
return [updated, removed];
}
function unflatenObject(flattenObject) {
const unFlatten = Object.create(null);
for (let [stringKeys, value] of Object.entries(flattenObject)) {
let chain = stringKeys.split('.')
let object = unFlatten
for (let [i, key] of chain.slice(0, -1).entries()) {
if (!object[key]) {
let needArray = Number.isInteger(Number(chain[+i + 1]))
object[key] = needArray ? [] : Object.create(null)
}
object = object[key];
}
let lastkey = chain.pop();
object[lastkey] = value;
}
return unFlatten;
}
下面是一个JavaScript库，可以用来查找两个JavaScript对象之间的差异:
Github URL:
https://github.com/cosmicanant/recursive-diff
npm捷的url:北京方位www.npmjs.犯下/ recursiff
递归-diff库可以在浏览器中使用，也可以在基于Node.js的服务器端应用程序中使用。对于浏览器，它可以使用如下:
<script type="text" src="https://unpkg.com/recursive-diff@latest/dist/recursive-diff.min.js"/>
<script type="text/javascript">
const ob1 = {a:1, b: [2,3]};
const ob2 = {a:2, b: [3,3,1]};
const delta = recursiveDiff.getDiff(ob1,ob2);
/* console.log(delta) will dump following data
[
{path: ['a'], op: 'update', val: 2}
{path: ['b', '0'], op: 'update',val: 3},
{path: ['b',2], op: 'add', val: 1 },
]
*/
const ob3 = recursiveDiff.applyDiff(ob1, delta); //expect ob3 is deep equal to ob2
</script>
而在一个基于node.js的应用程序中，它可以这样使用:
const diff = require('recursive-diff');
const ob1 = {a: 1}, ob2: {b:2};
const diff = diff.getDiff(ob1, ob2);
我修改了@sbgoran的答案，这样得到的diff对象只包括改变的值，省略了相同的值。此外，它同时显示原始值和更新后的值。
var deepDiffMapper = function () {
return {
VALUE_CREATED: 'created',
VALUE_UPDATED: 'updated',
VALUE_DELETED: 'deleted',
VALUE_UNCHANGED: '---',
map: function (obj1, obj2) {
if (this.isFunction(obj1) || this.isFunction(obj2)) {
throw 'Invalid argument. Function given, object expected.';
}
if (this.isValue(obj1) || this.isValue(obj2)) {
let returnObj = {
type: this.compareValues(obj1, obj2),
original: obj1,
updated: obj2,
};
if (returnObj.type != this.VALUE_UNCHANGED) {
return returnObj;
}
return undefined;
}
var diff = {};
let foundKeys = {};
for (var key in obj1) {
if (this.isFunction(obj1[key])) {
continue;
}
var value2 = undefined;
if (obj2[key] !== undefined) {
value2 = obj2[key];
}
let mapValue = this.map(obj1[key], value2);
foundKeys[key] = true;
if (mapValue) {
diff[key] = mapValue;
}
}
for (var key in obj2) {
if (this.isFunction(obj2[key]) || foundKeys[key] !== undefined) {
continue;
}
let mapValue = this.map(undefined, obj2[key]);
if (mapValue) {
diff[key] = mapValue;
}
}
//2020-06-13: object length code copied from https://stackoverflow.com/a/13190981/2336212
if (Object.keys(diff).length > 0) {
return diff;
}
return undefined;
},
compareValues: function (value1, value2) {
if (value1 === value2) {
return this.VALUE_UNCHANGED;
}
if (this.isDate(value1) && this.isDate(value2) && value1.getTime() === value2.getTime()) {
return this.VALUE_UNCHANGED;
}
if (value1 === undefined) {
return this.VALUE_CREATED;
}
if (value2 === undefined) {
return this.VALUE_DELETED;
}
return this.VALUE_UPDATED;
},
isFunction: function (x) {
return Object.prototype.toString.call(x) === '[object Function]';
},
isArray: function (x) {
return Object.prototype.toString.call(x) === '[object Array]';
},
isDate: function (x) {
return Object.prototype.toString.call(x) === '[object Date]';
},
isObject: function (x) {
return Object.prototype.toString.call(x) === '[object Object]';
},
isValue: function (x) {
return !this.isObject(x) && !this.isArray(x);
}
}
}();
