使用React导航的React本机组件中未定义的未声明容器

Question

我的问题是，我想访问一个组件中的容器，但它似乎是未定义的。

undefined alert image

我使用的是Unstated，正如您所看到的，这是我在容器文件(login-tainer.js)中的代码：

import { Container } from 'unstated'
class LoginContainer extends Container {
    constructor(props){
        super(props)
        this.state = {
            stepNumber: 0,
        }
    }
}
export default new LoginContainer()

这是app.js：

import React, { Component } from 'react'
import {  createStackNavigator, createSwitchNavigator } from 'react-navigation'
import { Provider } from 'unstated'
import LoginContainer from './containers/login-container'
import Home from './screens/home'
import Splash from './screens/splash'
import Login from './screens/login'
import Intro from './screens/intro'

export default class App extends Component {
  render() {
    return (
      <Provider inject={[LoginContainer]}>          
          <AuthStack/>                            
      </Provider>
    )
  }
}

const SplashStack = createStackNavigator(...)

const AppStack = createStackNavigator(...)

const AuthStack = createStackNavigator(
  {
    Intro: { screen: Intro},
    Login: { screen: Login}
  },
  {
    headerMode: "none",
    initialRouteName: "Intro"
  }
)

const SwitchNavigator = createSwitchNavigator(...)

这就是login.js：

import React, { Component } from 'react'
import { Text, View } from 'react-native'

export default class Login extends Component {
  constructor(props){
    super(props)
  }

  render() {
    // const { state: {stepNumber} } = this.props.loginContainer
    alert(this.props.LoginContainer)
    return (
      <View>
        <Text>  someText  </Text>
      </View>
    )
  }
}

我之前尝试使用Subscribe组件将容器注入到我的应用程序中，但我得到了与这里相同的结果。

使用

• react-native 0.58.6
• react-navigation 2.13.0 (由于v3中的一些错误)
• unstated 2.1.1

Answer 1

未声明的真正伟大之处在于它的实现非常简单。只要把你的渲染组件包装在Unstated的<Subscribe to></Subscribe>标签里就可以了，无论什么时候你在容器里setState()，所有Components到它的Subscribe都会用Container更新后的state属性值重新渲染。

    import React, { Component } from 'react';
    import { Text, View } from 'react-native';
    import { Subscribe } from 'unstated';

    import LoginContainer from './containers/login-container';

    export default class Login extends Component {
      constructor(props){
        super(props)
      }

      render() {
        return (
          <Subscribe to={[LoginContainer, AnotherContainer]}>
            {(container, another) => (
              <View>
                <Text>{container.state.stepNumber}</Text>
              </View>
            })
          </Subscribe>
        );
      }
    }

更新:或者用这种特别的方式来做。创建此文件后：

WithUnstated.js

import React, { PureComponent } from "react";
import { Subscribe } from "unstated";

import DefaultStore from "../store/DefaultStore";

const withUnstated = (
  WrappedComponent,
  Stores = [DefaultStore],
  navigationOptions
) =>
  class extends PureComponent {
    static navigationOptions = navigationOptions;

    render() {
      return (
        <Subscribe to={Stores}>
          {(...stores) => {
            const allStores = stores.reduce(
              (acc, v) => ({ ...acc, [v.displayName]: { ...v } }),
              {}
            );
            return <WrappedComponent {...allStores} {...this.props} />;
          }}
        </Subscribe>
      );
    }
  };

export default withUnstated;

然后像这样包装你的组件：

import React, { Component } from 'react';
import { Text, View } from 'react-native';
import { Subscribe } from 'unstated';

import LoginContainer from './containers/login-container';
import AnotherContainer from './containers/another-container';

class Login extends Component {
  constructor(props){
    super(props)
  }

  render() {
    const {LoginContainer: container} = this.props;
    return (
      <View>
        <Text>{container.state.stepNumber}</Text>
      </View>
    );
  }
}

export default withUnstated(Login, [LoginContainer, AnotherContainer])