小编Par*_*ism的帖子

我只是制作一个简单的应用程序来学习与redux的异步.我已经完成了所有工作,现在我只想在网页上显示实际状态.现在,我如何在render方法中实际访问商店的状态？

这是我的代码(一切都在一页,因为我只是在学习):

const initialState = {
        fetching: false,
        fetched: false,
        items: [],
        error: null
    }

const reducer = (state=initialState, action) => {
    switch (action.type) {
        case "REQUEST_PENDING": {
            return {...state, fetching: true};
        }
        case "REQUEST_FULFILLED": {
            return {
                ...state,
                fetching: false,
                fetched: true,
                items: action.payload
            }
        }
        case "REQUEST_REJECTED": {
            return {...state, fetching: false, error: action.payload}   
        }
        default: 
            return state;
    }
};

const middleware = applyMiddleware(promise(), thunk, logger());
const store = createStore(reducer, middleware);

store.dispatch({
    type: "REQUEST",
    payload: fetch('http://localhost:8000/list').then((res)=>res.json())
});

store.dispatch({ …

我收到此错误,我在修复此问题时遇到了很多麻烦.

我在这里尝试做的是有3个不同的屏幕,并有一个导航到每个屏幕的tabbar.

这是我的索引:

import React, { Component } from 'react';
import { AppRegistry, Navigator, StyleSheet, View, Text } from 'react-native';

import Nav from './app/components/Nav';
import Screen from './app/Screen';

import Tabs from 'react-native-tabs'

import SwitchView from './SwitchView';

class Proj extends Component {

constructor(props){
    super(props);
}

render(){
    var x = "FeedView";
    return(

          <View style={styles.container}>
            <Tabs selected={x} style={{backgroundColor:'white'}}
                  selectedStyle={{color:'red'}} onSelect={el=> {x = el.props.name}}>
                <Text name="FeedView">First</Text>
                <Text name="WikiView" selectedIconStyle={{borderTopWidth:2,borderTopColor:'red'}}>Second</Text>
                <Text name="BoardView">Third</Text>
            </Tabs>

            <SwitchView id={x}/>

          </View>
    );
}
}

const styles = StyleSheet.create({
container: { …

如何通过JSON文件解析检索其所有数据并在我的代码中使用它？

我已经尝试导入该文件并尝试使用控制台记录它,但它只是打印对象{}:

import jsonData from "./file.json";
console.log(jsonData);

这是我的file.json看起来像:

[
    {
      "id": 1,
      "gender": "Female",
      "first_name": "Helen",
      "last_name": "Nguyen",
      "email": "hnguyen0@bloomberg.com",
      "ip_address": "227.211.25.18"
    }, {
      "id": 2,
      "gender": "Male",
      "first_name": "Carlos",
      "last_name": "Fowler",
      "email": "cfowler1@gnu.org",
      "ip_address": "214.248.201.11"
    }
]

我希望能够访问每个组件的名字和姓氏,并在网站上打印.

我试图跟踪每篇文章中的分数并显示它.但是,当它缺少对象中的向上或向下项目时,我会遇到问题.

这是我所有投票的数据:

const votes = {
  "1": {
    "up": [
      "12345",
      "12346"
    ],
    "down": [
      "22456"
    ],
  },
  "2": {
    "up": [
      "12345",
      "12346"
    ],
    "down": [
      "22456",
      "25214",
      "23612"
    ]
  }
}

export default votes;

这是我如何处理它的权利,但这种要求必须有两个"up"和"down"的对象.

<div style={vote}>
    {votes[id] ? votes[id].up.length - votes[id].down.length : 0 }
</div>

因此,在此情况下,你必须只在up元素,我希望得到的结果是唯一的了长度.同样的情况下来:

"3": {
   "up": [
      "12345",
      "22341"
   ]
} //this would output a score of 2

任何帮助将不胜感激,谢谢!

我想在反应中修改一个 JSON 文件。有什么办法吗？

我有这个代码，当我点击一个 html 元素时它会运行。最后它调用 VoteTracking，这是我实际修改我的 json 文件的函数。

    handleChange(val){
            const { voted, score, imgup, imgdown, deviceKey } = this.state;
            const { id } = this.props;
            var x = this.state.score, vote = val;

            var clr;
            if (val) clr="#d98832"; else clr = "#3d3dff";

            if(!voted) {
                x += val;
                this.setState({voted: val, score: x, color: clr });
            }
            else if(Math.abs(voted)){
                if (voted == val){
                    vote = 0;
                    x -= val;
                    this.setState({voted: 0, score: x, color: "#6e6e6e"});
                }
                else {
                    x += (2* val); …