我有一个对象可以是任意数量的级别，并且可以具有任何现有属性。 例如：
var obj = {
db: {
mongodb: {
host: 'localhost'
}
}
};
在那我想设置（或覆盖）属性如下：
set('db.mongodb.user', 'root');
// or:
set('foo.bar', 'baz');
属性字符串可以有任何深度，值可以是任何类型/东西 如果属性键已经存在，则不需要合并作为值的对象和数组。
上一个示例将生成以下对象：
var obj = {
db: {
mongodb: {
host: 'localhost',
user: 'root'
}
},
foo: {
bar: baz
}
};
我怎样才能实现这样的功能？
答案 0 :(得分：67)
此函数使用您指定的参数，应添加/更新obj容器中的数据。请注意，您需要跟踪obj模式中的哪些元素是容器，哪些是值（字符串，整数等），否则您将开始抛出异常。
obj = {}; // global object
function set(path, value) {
var schema = obj; // a moving reference to internal objects within obj
var pList = path.split('.');
var len = pList.length;
for(var i = 0; i < len-1; i++) {
var elem = pList[i];
if( !schema[elem] ) schema[elem] = {}
schema = schema[elem];
}
schema[pList[len-1]] = value;
}
set('mongo.db.user', 'root');
答案 1 :(得分：38)
Lodash采用_.set()方法。
for k = 1:5
totalBinary = totalBinary | binaryImage;
subplot(1,2,2); imshow(totalBinary); drawnow
subplot(1,2,1); %imshow(tophatImage) % <-- Remove this
hFH = imfreehand();
binaryImage = createMask(hFH);
end
答案 2 :(得分：9)
有点晚了，但这里有一个非库，更简单的答案：
/**
* Dynamically sets a deeply nested value in an object.
* Optionally "bores" a path to it if its undefined.
* @function
* @param {!object} obj - The object which contains the value you want to change/set.
* @param {!array} path - The array representation of path to the value you want to change/set.
* @param {!mixed} value - The value you want to set it to.
* @param {boolean} setrecursively - If true, will set value of non-existing path as well.
*/
function setDeep(obj, path, value, setrecursively = false) {
let level = 0;
path.reduce((a, b)=>{
level++;
if (setrecursively && typeof a[b] === "undefined" && level !== path.length){
a[b] = {};
return a[b];
}
if (level === path.length){
a[b] = value;
return value;
} else {
return a[b];
}
}, obj);
}
我所做的这个功能可以完全满足您的需求，而且可以做多一点。
假设我们想要更改深度嵌套在此对象中的目标值：
let myObj = {
level1: {
level2: {
target: 1
}
}
}
所以我们会这样调用我们的函数：
setDeep(myObj, ["level1", "level2", "target1"], 3);
将导致：
myObj = { 1级： { level2：{ 目标：3 } } }
将set recursively flag设置为true将设置对象（如果它们不存在）。
setDeep(myObj, ["new", "path", "target"], 3);
将导致：
obj = myObj = {
new: {
path: {
target: 3
}
},
level1: {
level2: {
target: 3
}
}
}
答案 3 :(得分：6)
Lodash有一个名为update的方法，可以完全满足您的需求。
此方法接收以下参数：
在您的示例中，它看起来像这样：
_.update(obj, 'db.mongodb.user', function(originalValue) {
return 'root'
})
答案 4 :(得分：6)
受@ bpmason1的回答启发：
function leaf(obj, path, value) {
const pList = path.split('.');
const key = pList.pop();
const pointer = pList.reduce((accumulator, currentValue) => {
if (accumulator[currentValue] === undefined) accumulator[currentValue] = {};
return accumulator[currentValue];
}, obj);
pointer[key] = value;
return obj;
}
示例：
const obj = {
boats: {
m1: 'lady blue'
}
};
leaf(obj, 'boats.m1', 'lady blue II');
leaf(obj, 'boats.m2', 'lady bird');
console.log(obj); // { boats: { m1: 'lady blue II', m2: 'lady bird' } }
答案 5 :(得分：2)
我们可以使用递归函数：
/**
* Sets a value of nested key string descriptor inside a Object.
* It changes the passed object.
* Ex:
* let obj = {a: {b:{c:'initial'}}}
* setNestedKey(obj, ['a', 'b', 'c'], 'changed-value')
* assert(obj === {a: {b:{c:'changed-value'}}})
*
* @param {[Object]} obj Object to set the nested key
* @param {[Array]} path An array to describe the path(Ex: ['a', 'b', 'c'])
* @param {[Object]} value Any value
*/
export const setNestedKey = (obj, path, value) => {
if (path.length === 1) {
obj[path] = value
return
}
return setNestedKey(obj[path[0]], path.slice(1), value)
}
这更简单！
答案 6 :(得分：2)
使用计算属性名称和 Rest参数，ES6也有很酷的方法。
const obj = {
levelOne: {
levelTwo: {
levelThree: "Set this one!"
}
}
}
const updatedObj = {
...obj,
levelOne: {
...obj.levelOne,
levelTwo: {
...obj.levelOne.levelTwo,
levelThree: "I am now updated!"
}
}
}
如果levelThree是动态属性，即设置levelTwo中的任何属性，则可以使用[propertyName]: "I am now updated!" propertyName保存levelTwo中的属性名称1}}。
答案 7 :(得分：2)
我只是使用ES6 +递归编写一个小函数来实现目标。
DESC我在更新状态的反应中使用了很多，它对我来说效果很好。
答案 8 :(得分：1)
如果您只需要更改更深层次的嵌套对象，那么另一种方法可能是引用该对象。由于JS对象由其引用处理，因此您可以创建对具有字符串键访问权限的对象的引用。
示例：
// The object we want to modify:
var obj = {
db: {
mongodb: {
host: 'localhost',
user: 'root'
}
},
foo: {
bar: baz
}
};
var key1 = 'mongodb';
var key2 = 'host';
var myRef = obj.db[key1]; //this creates a reference to obj.db['mongodb']
myRef[key2] = 'my new string';
// The object now looks like:
var obj = {
db: {
mongodb: {
host: 'my new string',
user: 'root'
}
},
foo: {
bar: baz
}
};
答案 9 :(得分：1)
我想出了自己的解决方案，它使用了纯es6和不会改变原始对象的递归。
const setNestedProp = (obj = {}, [first, ...rest] , value) => ({
...obj,
[first]: rest.length
? setNestedProp(obj[first], rest, value)
: value
});
const result = setNestedProp({}, ["first", "second", "a"],
"foo");
const result2 = setNestedProp(result, ["first", "second", "b"], "bar");
console.log(result);
console.log(result2);
答案 10 :(得分：1)
我创建了gist，用于根据正确答案通过字符串设置和获取obj值。您可以下载它或将其作为npm / yarn软件包使用。
// yarn add gist:5ceba1081bbf0162b98860b34a511a92
// npm install gist:5ceba1081bbf0162b98860b34a511a92
export const DeepObject = {
set: setDeep,
get: getDeep
};
// https://stackoverflow.com/a/6491621
function getDeep(obj: Object, path: string) {
path = path.replace(/\[(\w+)\]/g, '.$1'); // convert indexes to properties
path = path.replace(/^\./, ''); // strip a leading dot
const a = path.split('.');
for (let i = 0, l = a.length; i < l; ++i) {
const n = a[i];
if (n in obj) {
obj = obj[n];
} else {
return;
}
}
return obj;
}
// https://stackoverflow.com/a/18937118
function setDeep(obj: Object, path: string, value: any) {
let schema = obj; // a moving reference to internal objects within obj
const pList = path.split('.');
const len = pList.length;
for (let i = 0; i < len - 1; i++) {
const elem = pList[i];
if (!schema[elem]) {
schema[elem] = {};
}
schema = schema[elem];
}
schema[pList[len - 1]] = value;
}
// Usage
// import {DeepObject} from 'somePath'
//
// const obj = {
// a: 4,
// b: {
// c: {
// d: 2
// }
// }
// };
//
// DeepObject.set(obj, 'b.c.d', 10); // sets obj.b.c.d to 10
// console.log(DeepObject.get(obj, 'b.c.d')); // returns 10
答案 11 :(得分：1)
另一种方法是使用递归来挖掘对象：
(function(root){
function NestedSetterAndGetter(){
function setValueByArray(obj, parts, value){
if(!parts){
throw 'No parts array passed in';
}
if(parts.length === 0){
throw 'parts should never have a length of 0';
}
if(parts.length === 1){
obj[parts[0]] = value;
} else {
var next = parts.shift();
if(!obj[next]){
obj[next] = {};
}
setValueByArray(obj[next], parts, value);
}
}
function getValueByArray(obj, parts, value){
if(!parts) {
return null;
}
if(parts.length === 1){
return obj[parts[0]];
} else {
var next = parts.shift();
if(!obj[next]){
return null;
}
return getValueByArray(obj[next], parts, value);
}
}
this.set = function(obj, path, value) {
setValueByArray(obj, path.split('.'), value);
};
this.get = function(obj, path){
return getValueByArray(obj, path.split('.'));
};
}
root.NestedSetterAndGetter = NestedSetterAndGetter;
})(this);
var setter = new this.NestedSetterAndGetter();
var o = {};
setter.set(o, 'a.b.c', 'apple');
console.log(o); //=> { a: { b: { c: 'apple'}}}
var z = { a: { b: { c: { d: 'test' } } } };
setter.set(z, 'a.b.c', {dd: 'zzz'});
console.log(JSON.stringify(z)); //=> {"a":{"b":{"c":{"dd":"zzz"}}}}
console.log(JSON.stringify(setter.get(z, 'a.b.c'))); //=> {"dd":"zzz"}
console.log(JSON.stringify(setter.get(z, 'a.b'))); //=> {"c":{"dd":"zzz"}}
答案 12 :(得分：0)
如果您想要一个需要先验属性存在的函数，则可以使用类似的方法，它还会返回一个标志，说明它是否设法找到并设置了嵌套属性。
function set(obj, path, value) {
var parts = (path || '').split('.');
// using 'every' so we can return a flag stating whether we managed to set the value.
return parts.every((p, i) => {
if (!obj) return false; // cancel early as we havent found a nested prop.
if (i === parts.length - 1){ // we're at the final part of the path.
obj[parts[i]] = value;
}else{
obj = obj[parts[i]]; // overwrite the functions reference of the object with the nested one.
}
return true;
});
}
答案 13 :(得分：0)
答案 14 :(得分：0)
我需要实现相同的目的，但是在Node.js中... 因此，我找到了一个不错的模块：https://www.npmjs.com/package/nested-property
示例：
var mod = require("nested-property");
var obj = {
a: {
b: {
c: {
d: 5
}
}
}
};
console.log(mod.get(obj, "a.b.c.d"));
mod.set(obj, "a.b.c.d", 6);
console.log(mod.get(obj, "a.b.c.d"));
答案 15 :(得分：0)
受ClojureScript的assoc-in（https://github.com/clojure/clojurescript/blob/master/src/main/cljs/cljs/core.cljs#L5280）启发，使用递归：
/**
* Associate value (v) in object/array (m) at key/index (k).
* If m is falsy, use new object.
* Returns the updated object/array.
*/
function assoc(m, k, v) {
m = (m || {});
m[k] = v;
return m;
}
/**
* Associate value (v) in nested object/array (m) using sequence of keys (ks)
* to identify the path to the nested key/index.
* If one of the values in the nested object/array doesn't exist, it adds
* a new object.
*/
function assoc_in(m={}, [k, ...ks], v) {
return ks.length ? assoc(m, k, assoc_in(m[k], ks, v)) : assoc(m, k, v);
}
/**
* Associate value (v) in nested object/array (m) using key string notation (s)
* (e.g. "k1.k2").
*/
function set(m, s, v) {
ks = s.split(".");
return assoc_in(m, ks, v);
}
注意：
通过提供的实现，
assoc_in({"a": 1}, ["a", "b"], 2)
返回
{"a": 1}
在这种情况下，我希望它抛出一个错误。如果需要，可以在assoc中添加检查以确认m是对象还是数组，否则抛出错误。
答案 16 :(得分：0)
我试图简短地编写此 set方法，它可能会对某人有所帮助！
function set(obj, key, value) {
let keys = key.split('.');
if(keys.length<2){ obj[key] = value; return obj; }
let lastKey = keys.pop();
let fun = `obj.${keys.join('.')} = {${lastKey}: '${value}'};`;
return new Function(fun)();
}
var obj = {
"hello": {
"world": "test"
}
};
set(obj, "hello.world", 'test updated');
console.log(obj);
set(obj, "hello.world.again", 'hello again');
console.log(obj);
set(obj, "hello.world.again.onece_again", 'hello once again');
console.log(obj);
答案 17 :(得分：0)
const set = (o, path, value) => {
const props = path.split('.');
const prop = props.shift()
if (props.length === 0) {
o[prop] = value
} else {
o[prop] = o[prop] ?? {}
set(o[prop], props.join('.'), value)
}
}
答案 18 :(得分：0)
晚会 - 这是一个普通的js函数，它接受一个路径作为参数并返回修改后的对象/json
let orig_json = {
string: "Hi",
number: 0,
boolean: false,
object: {
subString: "Hello",
subNumber: 1,
subBoolean: true,
subObject: {
subSubString: "Hello World"
},
subArray: ["-1", "-2", "-3"]
},
array: ["1", "2", "3"]
}
function changeValue(obj_path, value, json) {
let keys = obj_path.split(".")
let obj = { ...json },
tmpobj = {},
prevobj = {}
for (let x = keys.length - 1; x >= 0; x--) {
if (x == 0) {
obj[keys[0]] = tmpobj
} else {
let toeval = 'json.' + keys.slice(0, x).join('.');
prevobj = { ...tmpobj
}
tmpobj = eval(toeval);
if (x == keys.length - 1) tmpobj[keys[x]] = value
else {
tmpobj[keys[x]] = prevobj
}
}
}
return obj
}
let newjson = changeValue("object.subObject.subSubString", "Goodbye world", orig_json);
console.log(newjson)答案 19 :(得分：0)
另一种添加或覆盖属性的解决方案：
function propertySetter(property, value) {
const sampleObject = {
string: "Hi",
number: 0,
boolean: false,
object: {
subString: "Hello",
subNumber: 1,
subBoolean: true,
subObject: {
subSubString: "Hello World",
},
subArray: ["-1", "-2", "-3"],
},
array: ["1", "2", "3"],
};
const keys = property.split(".");
const propertyName = keys.pop();
let propertyParent = sampleObject;
while (keys.length > 0) {
const key = keys.shift();
if (!(key in propertyParent)) {
propertyParent[key] = {};
}
propertyParent = propertyParent[key];
}
propertyParent[propertyName] = value;
return sampleObject;
}
console.log(propertySetter("object.subObject.anotherSubString", "Hello you"));
console.log(propertySetter("object.subObject.subSubString", "Hello Earth"));
console.log(propertySetter("object.subObject.nextSubString.subSubSubString", "Helloooo"));答案 20 :(得分：0)
扩展 @bpmason1 提供的已接受答案，以支持字符串路径中的数组，例如字符串路径可以是 'db.mongodb.users[0].name' 和 'db.mongodb.users[1].name'。
它会设置属性值，如果不存在，将被创建。
var obj = {};
function set(path, value) {
var schema = obj;
var keysList = path.split('.');
var len = keysList.length;
for (var i = 0; i < len - 1; i++) {
var key = keysList[i];
// checking if key represents an array element e.g. users[0]
if (key.includes('[')) {
//getting propertyName 'users' form key 'users[0]'
var propertyName = key.substr(0, key.length - key.substr(key.indexOf("["), key.length - key.indexOf("[")).length);
if (!schema[propertyName]) {
schema[propertyName] = [];
}
// schema['users'][getting index 0 from 'users[0]']
if (!schema[propertyName][parseInt(key.substr(key.indexOf("[") + 1, key.indexOf("]") - key.indexOf("[") - 1))]) {
// if it doesn't exist create and initialise it
schema = schema[propertyName][parseInt(key.substr(key.indexOf("[") + 1, key.indexOf("]") - key.indexOf("[") - 1))] = {};
} else {
schema = schema[propertyName][parseInt(key.substr(key.indexOf("[") + 1, key.indexOf("]") - key.indexOf("[") - 1))];
}
continue;
}
if (!schema[key]) {
schema[key] = {};
}
schema = schema[key];
} //loop ends
// if last key is array element
if (keysList[len - 1].includes('[')) {
//getting propertyName 'users' form key 'users[0]'
var propertyName = keysList[len - 1].substr(0, keysList[len - 1].length - keysList[len - 1].substr(keysList[len - 1].indexOf("["), keysList[len - 1].length - keysList[len - 1].indexOf("[")).length);
if (!schema[propertyName]) {
schema[propertyName] = [];
}
// schema[users][0] = value;
schema[propertyName][parseInt(keysList[len - 1].substr(keysList[len - 1].indexOf("[") + 1, keysList[len - 1].indexOf("]") - keysList[len - 1].indexOf("[") - 1))] = value;
} else {
schema[keysList[len - 1]] = value;
}
}
// will create if not exist
set("mongo.db.users[0].name.firstname", "hii0");
set("mongo.db.users[1].name.firstname", "hii1");
set("mongo.db.users[2].name", {
"firstname": "hii2"
});
set("mongo.db.other", "xx");
console.log(obj);
// will set if exist
set("mongo.db.other", "yy");
console.log(obj);