javascript - 如何为整个 MobX 可观察数组设置新值

Question

在 MobX 中，如何在不重新设置每个值的情况下为整个可观察数组设置新值？

首先想到的是:

let arr = observable([]);
autorun(() => {
  console.log('my array changed!');
});
arr = ['foo', 'bar'];

但这不会触发 autorun，我只是删除了我的 observable array 并用新值/数组替换它。

那么，正确的做法是什么？

我的解决方案是使用另一个带有 setter 的变量，并在 setter 函数中 将可观察数组 index 更改为 index，替换、添加和删除索引。像这样:

( jsFiddle here )

const {observable, computed, extendObservable} = mobx;
const {observer} = mobxReact;
const {Component} = React;
const {render} = ReactDOM
const {autorun} = mobx

class Store {
    @observable entries = [1,2,3,4,5];
    set rows(arr) {
        // add new values
        for (let i = 0, l = arr.length; i < l; i++) {
            this.entries[i] = arr[i];
        }
        // remove rest of entries
        let diff = this.entries.length - arr.length;
        if (diff > 0) {
            while (diff > 0) {
                this.entries.pop();
                diff--;
            }
        }
    }
}
const store = new Store();

@observer
class App extends Component {
    updateRows(){
        return this.props.entries.map(
            (row, i) => <p key={i}>{row}</p>
        );
    }
    render() {
        const rows = this.updateRows();
        return <div>{rows}</div>;
    }
}

setTimeout(() => {
    store.rows = ['foo', 'bar'];
    document.body.innerHTML += 'Timeout fired...';
}, 1000);


render(
    <App entries={store.entries} />,
    document.getElementById('mount')
);

这是正确的方法吗？
或者有没有办法只使用同一个变量为整个数组重新赋值？

Answer 1

TLDR; 使用 store.entries.replace(['foo', 'bar']);

我找到了一个方法 .replace() ，它将替换整个数组的内容并触发渲染。我找到了after a suggestion关于 clear() 方法，并从那里更仔细地研究 the docs

.replace(newItems);

Replaces all existing entries in the array with new ones.

代码看起来像这样:

( jsFiddle )

const {observable, autorun} = mobx;

class Store {
     @observable arr = [1,2,3,4,5];
}
const store = new Store();
autorun(() => {
  console.log('my array changed!', store.arr.slice());
});
setTimeout(() => {
   store.arr.replace(['foo', 'bar']);
}, 1000);

整个代码是:

( jsFiddle )

const {observable, computed, extendObservable} = mobx;
const {observer} = mobxReact;
const {Component} = React;
const {render} = ReactDOM
const {autorun} = mobx

class Store {
     @observable entries = [1,2,3,4,5];
}
const store = new Store();

@observer
class App extends Component {
    updateRows(){
        return this.props.entries.map(
            (row, i) => <p key={i}>{row}</p>
        );
    }
  render() {
  const rows = this.updateRows();
    return <div>{rows}</div>;
  }
}

setTimeout(() => {
    store.entries.replace(['foo', 'bar']);
}, 1000);


render(
  <App entries={store.entries} />,
  document.getElementById('mount')
);