用unstated.js解构

Question

我有一个未声明的容器：

import { Container } from 'unstated';
import axios from 'axios';

export default class CurrenciesContainer extends Container {
  state = { currencies: null };
  async fetch() {
    const { data: currencies } = await axios.get('http://localhost:8080/get-currencies');
    this.setState({ currencies });
  }
}

利用它的这个功能：

static renderCurrencies() {
  return (
    <Subscribe to={[CurrenciesContainer]}>
      {(currencies) => {
        if (!currencies.state.currencies) {
          currencies.fetch();
        }
        return <small>Currencies: {currencies.state.currencies}</small>;
      }}
    </Subscribe>
  );
}

我想尝试对进入<Subscribe>的params进行如下的重构：

static renderCurrencies() {
  return (
    <Subscribe to={[CurrenciesContainer]}>
      {({ state, fetch }) => {
        if (!state.currencies) {
          fetch();
        }
        return <small>Currencies: {state.currencies}</small>;
      }}
    </Subscribe>
  );
}

但这与Uncaught (in promise) TypeError: this.setState is not a function不同

显然，它没有正确地绑定，但是我不知道为什么函数的破坏会改变它的绑定。有人能给出这样的解释/方法吗？谢谢!

Answer 1

将async fetch() {}替换为fetch = async () => {}，以实现正确的绑定。

在未声明的容器中尝试以下操作：

import { Container } from 'unstated';
import axios from 'axios';

export default class CurrenciesContainer extends Container {
  state = { currencies: null };
  fetch = async () => {
    const { data: currencies } = await axios.get('http://localhost:8080/get-currencies');
    this.setState({ currencies });
 }
}