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?
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
对于在2022年读书的人来说:
constructor(props) {
super(props);
this.state = {
someProperty: {
flag: true
}
otherValues: '',
errors: {}
};
this.handleInputChange = this.handleInputChange.bind(this);
}
handleInputChange(event) {
const target = event.target;
const value = target.type === 'checkbox' ? target.checked : target.value;
const name = target.name;
const someProperty = { ...this.state.someProperty };
someProperty[name] = value;
this.setState({
someProperty: someProperty
});
}
.......
其他回答
下面是一个完整的例子,使用嵌套状态(一层)和这个答案中的解决方案,对于一个实现为类的组件:
class CaveEditModal extends React.Component {
// ...
constructor(props, context) {
super(props);
this.state = {
tabValue: '1',
isModalOpen: this.props.isModalOpen,
// ...
caveData: {
latitude: 1,
longitude: 2
}
};
// ...
const updateNestedFieldEvent = fullKey => ev => {
var [parentProperty, _key] = fullKey.split(".", 2);
this.setState({[parentProperty]: { ...this.state[parentProperty], [_key]: ev.target.value} });
};
// ...
this.handleLatitudeChange = updateNestedFieldEvent('caveData.latitude');
this.handleLongitudeChange = updateNestedFieldEvent('caveData.longitude');
}
render () {
return (
<div>
<TextField id="latitude" label="Latitude" type="number" value={this.state.caveData.latitude} onChange={this.handleLatitudeChange} />
<TextField id="longitude" label="Longitude" type="number" value={this.state.caveData.longitude} onChange={this.handleLongitudeChange} />
<span>lat={this.state.caveData.latitude} long={this.state.caveData.longitude}</span>
</div>
);
};
}
注意,状态更新器函数updateNestedFieldEvent只适用于一层嵌套对象,比如a.b,而不是a.b.c。
把它写在一行里
this.setState({ someProperty: { ...this.state.someProperty, flag: false} });
const newState = Object.assign({}, this.state);
newState.property.nestedProperty = "new value";
this.setState(newState);
如果你在你的项目中使用formik,它有一些简单的方法来处理这些东西。下面是使用formik最简单的方法。
首先在formik initivalues属性或react中设置初始值。状态
这里,初始值是在react状态下定义的
state = {
data: {
fy: {
active: "N"
}
}
}
在formik initiValues属性中定义以上的initialValues字段
<Formik
initialValues={this.state.data}
onSubmit={(values, actions)=> {...your actions goes here}}
>
{({ isSubmitting }) => (
<Form>
<Field type="checkbox" name="fy.active" onChange={(e) => {
const value = e.target.checked;
if(value) setFieldValue('fy.active', 'Y')
else setFieldValue('fy.active', 'N')
}}/>
</Form>
)}
</Formik>
制作一个控制台来检查状态更新为字符串而不是布尔值formik setFieldValue函数来设置状态或使用react调试器工具来查看formik状态值的变化。
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)