我试图通过使用这样的嵌套属性来组织我的状态:
this.state = {
someProperty: {
flag:true
}
}
但是像这样更新状态，
this.setState({ someProperty.flag: false });
是行不通的。怎样才能正确地做到这一点呢?
当前回答
这样就足够了，
const isObject = (thing) => {
if(thing &&
typeof thing === 'object' &&
typeof thing !== null
&& !(Array.isArray(thing))
){
return true;
}
return false;
}
/*
Call with an array containing the path to the property you want to access
And the current component/redux state.
For example if we want to update `hello` within the following obj
const obj = {
somePrimitive:false,
someNestedObj:{
hello:1
}
}
we would do :
//clone the object
const cloned = clone(['someNestedObj','hello'],obj)
//Set the new value
cloned.someNestedObj.hello = 5;
*/
const clone = (arr, state) => {
let clonedObj = {...state}
const originalObj = clonedObj;
arr.forEach(property => {
if(!(property in clonedObj)){
throw new Error('State missing property')
}
if(isObject(clonedObj[property])){
clonedObj[property] = {...originalObj[property]};
clonedObj = clonedObj[property];
}
})
return originalObj;
}
const nestedObj = {
someProperty:true,
someNestedObj:{
someOtherProperty:true
}
}
const clonedObj = clone(['someProperty'], nestedObj);
console.log(clonedObj === nestedObj) //returns false
console.log(clonedObj.someProperty === nestedObj.someProperty) //returns true
console.log(clonedObj.someNestedObj === nestedObj.someNestedObj) //returns true
console.log()
const clonedObj2 = clone(['someProperty','someNestedObj','someOtherProperty'], nestedObj);
console.log(clonedObj2 === nestedObj) // returns false
console.log(clonedObj2.someNestedObj === nestedObj.someNestedObj) //returns false
//returns true (doesn't attempt to clone because its primitive type)
console.log(clonedObj2.someNestedObj.someOtherProperty === nestedObj.someNestedObj.someOtherProperty)
其他回答
为了让事情变得通用，我研究了@ShubhamKhatri和@Qwerty的答案。
状态对象
this.state = {
name: '',
grandParent: {
parent1: {
child: ''
},
parent2: {
child: ''
}
}
};
输入控件
<input
value={this.state.name}
onChange={this.updateState}
type="text"
name="name"
/>
<input
value={this.state.grandParent.parent1.child}
onChange={this.updateState}
type="text"
name="grandParent.parent1.child"
/>
<input
value={this.state.grandParent.parent2.child}
onChange={this.updateState}
type="text"
name="grandParent.parent2.child"
/>
updateState方法
setState作为@ShubhamKhatri的答案
updateState(event) {
const path = event.target.name.split('.');
const depth = path.length;
const oldstate = this.state;
const newstate = { ...oldstate };
let newStateLevel = newstate;
let oldStateLevel = oldstate;
for (let i = 0; i < depth; i += 1) {
if (i === depth - 1) {
newStateLevel[path[i]] = event.target.value;
} else {
newStateLevel[path[i]] = { ...oldStateLevel[path[i]] };
oldStateLevel = oldStateLevel[path[i]];
newStateLevel = newStateLevel[path[i]];
}
}
this.setState(newstate);
}
setState作为@Qwerty的答案
updateState(event) {
const path = event.target.name.split('.');
const depth = path.length;
const state = { ...this.state };
let ref = state;
for (let i = 0; i < depth; i += 1) {
if (i === depth - 1) {
ref[path[i]] = event.target.value;
} else {
ref = ref[path[i]];
}
}
this.setState(state);
}
注意:上述方法不适用于数组
我们使用Immer https://github.com/mweststrate/immer来处理这类问题。
只是在我们的一个组件中替换了这段代码
this.setState(prevState => ({
...prevState,
preferences: {
...prevState.preferences,
[key]: newValue
}
}));
用这个
import produce from 'immer';
this.setState(produce(draft => {
draft.preferences[key] = newValue;
}));
使用immer，您可以将您的状态作为“普通对象”处理。 神奇的事情发生在代理对象的幕后。
使用箭头函数代替，这应该做的把戏。
setItems((prevState) => {
prevState.nestedData = newNestedData;
prevState.nestedData1 = newNestedData1;
});
不要忘记使用箭头函数(prevState) =>{更新js赋值语句…}
这样就足够了，
const isObject = (thing) => {
if(thing &&
typeof thing === 'object' &&
typeof thing !== null
&& !(Array.isArray(thing))
){
return true;
}
return false;
}
/*
Call with an array containing the path to the property you want to access
And the current component/redux state.
For example if we want to update `hello` within the following obj
const obj = {
somePrimitive:false,
someNestedObj:{
hello:1
}
}
we would do :
//clone the object
const cloned = clone(['someNestedObj','hello'],obj)
//Set the new value
cloned.someNestedObj.hello = 5;
*/
const clone = (arr, state) => {
let clonedObj = {...state}
const originalObj = clonedObj;
arr.forEach(property => {
if(!(property in clonedObj)){
throw new Error('State missing property')
}
if(isObject(clonedObj[property])){
clonedObj[property] = {...originalObj[property]};
clonedObj = clonedObj[property];
}
})
return originalObj;
}
const nestedObj = {
someProperty:true,
someNestedObj:{
someOtherProperty:true
}
}
const clonedObj = clone(['someProperty'], nestedObj);
console.log(clonedObj === nestedObj) //returns false
console.log(clonedObj.someProperty === nestedObj.someProperty) //returns true
console.log(clonedObj.someNestedObj === nestedObj.someNestedObj) //returns true
console.log()
const clonedObj2 = clone(['someProperty','someNestedObj','someOtherProperty'], nestedObj);
console.log(clonedObj2 === nestedObj) // returns false
console.log(clonedObj2.someNestedObj === nestedObj.someNestedObj) //returns false
//returns true (doesn't attempt to clone because its primitive type)
console.log(clonedObj2.someNestedObj.someOtherProperty === nestedObj.someNestedObj.someOtherProperty)
你可以用对象展开来做这个 代码:
this.setState((state)=>({ someProperty:{...state.someProperty,flag:false}})
这将适用于更多嵌套的属性
