添加新帖子时动态路由不起作用

Question

在向我的博客添加帖子并为该帖子执行动态路由以显示详细信息时，我无法做到这一点。 动态路由仅适用于我之前保存在 state 上的数据。 不适用于新添加的数据。 this.props 仅显示我保存在 state 中的数据。 给我一些建议。 在添加显示加载的新车辆动态路线时。 它没有从 state 获取新数据。

应用程序.js：

import React, { Component } from 'react'
import './App.css';
import Addview from './components/Addview'
import {BrowserRouter,Route, Switch} from 'react-router-dom'
import Add from './components/Add'
import Vechile from './components/Vechile';
import View from './components/View'


class App extends Component {
  render() {
    return (
      <BrowserRouter>
      <div className='App container'>
        <h2 className='text-primary text-decoration-underline'>Vehicle Information</h2>
        {/* <Addview /> */}
          <Route exact Path='/' component ={Addview} />
        <Switch>
          <Route path = '/add' component={Add} />
          <Route path = '/view' component={View} />
          <Route path = '/:id' component ={Vechile} />
        </Switch>
      </div>
      </BrowserRouter>
    )
  }
}

export default App

rootReducer.js：

const initState={
    vechileInfo:[
        {id:'1' , model_name:'AUDI' , vehchile_type: 'SUV', mileage:"5km/lt", top_speed:'250km/hr', cost:'30lakh', sales_units: 4},
        {id:'2' , model_name:'BMW' , vehchile_type: 'Hatchback', mileage:"7km/lt",top_speed:'320km/hr', cost:'40lakh', sales_units: 2},
        {id:'3' , model_name:'Mercidez' , vehchile_type: 'SUV', mileage:"6km/lt", top_speed:'220km/hr', cost:'25lakh', sales_units: 6}
    ]
   
}
const rootReducer = (state = initState,action) =>{
    console.log(action) 
    switch(action.type){
    case "DELETE_VECHILE":
        let newVechileInfo= state.vechileInfo.filter(vechile=>{
            return action.id!==vechile.id
        })
        return{
            ...state,
            vechileInfo : newVechileInfo
        }
        case "ADD_VECHILE":
            action.vechile.id=Math.random();
            let vechileInfoAdd=[...state.vechileInfo,action.vechile]
            console.log(action,vechileInfoAdd)
        return{
            ...state,
            vechileInfo: vechileInfoAdd
        }
        case "SORT_SALES":
            let sortvechileInfo = action.vechile.sort((a,b)=>{
                // console.log(action)
                return (a.sales_units - b.sales_units)
            })
            return{
                ...state,
                vechileInfo : sortvechileInfo
            }
    }
    
    return state
}

export default rootReducer

添加视图.js：

import React from 'react'
import {Link,NavLink} from 'react-router-dom'

const Addview = () => {
    return (
        <div className='my-5'>
            <button type="button" class="btn btn-warning btn-lg"><Link to="/" className="text-decoration-none text-dark fw-bold">Go to Home</Link></button>
            <button type="button" class="btn btn-success btn-lg"><Link to="/add" className="text-decoration-none text-dark fw-bold">Add a vechile</Link></button>
            <button type="button" class="btn btn-danger btn-lg"><Link to="/view" className="text-decoration-none text-dark fw-bold">View Vechiles</Link> </button>
        </div>
    )
}

export default Addview

视图.js：

import React, { Component } from 'react'
import { connect } from "react-redux"
import {Link} from 'react-router-dom'

class View extends Component {

    handleClick=(id)=>{
         this.props.deleteVechile(id)
        // console.log(id)
    }

    handleClickSort=()=>{
        this.props.sortSales(this.props.vechileInfo)
    }
    

    render() {
        // console.log(this.props)
        const { vechileInfo } = this.props;
        const vechileList = vechileInfo.length ? (
            vechileInfo.map(vechile => {
                return(      
                    <tbody key={vechile.id}>    
                        <tr> 
                            <td><Link to ={'/' + vechile.id} className='text-decoration-none'>{vechile.model_name}</Link> </td>  
                            <td>{vechile.vehchile_type}</td>
                            <td>{vechile.mileage}</td>
                            <td>{vechile.top_speed}</td>
                            <td>{vechile.cost}</td>
                            <td>{vechile.sales_units}</td>
                            <td onClick={()=>{this.handleClick(vechile.id)}} ><a className='text-danger' href='#'>X</a></td>    
                        </tr>
                    </tbody>
                       
                )
            })
        ) : (
            
            <div className="text-dark">No vechile to display. Please add a vechile</div>
        )
        return (
            <div className='container'>
                <table className="table table-dark table-hover ">
                    <thead>
                        <tr>
                            <th scope="col">Model Name</th>
                            <th scope="col">Vechile Type</th>
                            <th scope="col">Top Speed</th>
                            <th scope="col">Mileage</th>
                            <th scope="col">Cost</th>
                            <th onClick={this.handleClickSort} scope="col">Sales Units</th>
                            <th scope="col"></th>
                        </tr>
                    </thead>
                {vechileList}
                </table>
            </div>
        )
    }
}

const mapStateToProps = (state,ownProps) => {
    console.log(ownProps)
    return {
        vechileInfo: state.vechileInfo
    }
}

const mapDispatchToProps = (dispatch) =>{   
    return{   
        deleteVechile: (id) =>{ dispatch({type: 'DELETE_VECHILE', id:id})},
        sortSales: (vechile) =>{dispatch({type:'SORT_SALES', vechile})}
    }
}

export default connect(mapStateToProps, mapDispatchToProps)(View)

添加.js：

import React, { Component } from 'react'
import { connect } from "react-redux"

class Add extends Component {
    state={   
        model_name:'',
        vehchile_type:'',
        mileage:'',
        top_speed:'',
        cost:'',
        sales_units:''
    }
    handleChange=(e)=>{
        this.setState({
            [e.target.id]: e.target.value
        })
    }
    handleSubmit=(e)=>{
        e.preventDefault();
        // console.log(this.state)
        this.props.addVechile(this.state)
        this.props.history.push('/View')
    }
    render() {
        return (
            <div>
                <form className="row g-3" onSubmit={this.handleSubmit}>
                    <div className="col-md-6">
                        <label for="model_name" className="form-label">Model Name</label>
                        <input type="text" className="form-control" id="model_name" required onChange={this.handleChange}/>
                    </div>
                    <div className="col-md-6">
                        <label for="vehchile_type" className="form-label">Vechile Type</label>
                        <input type="text" className="form-control" id="vehchile_type" required onChange={this.handleChange}/>
                    </div>
                    <div className="col-md-6">
                        <label for="mileage" className="form-label">Mileage</label>
                        <input type="text" className="form-control" id="mileage" required onChange={this.handleChange}/>
                    </div>
                    <div className="col-md-6">
                        <label for="top_speed" className="form-label">Top Speed</label>
                        <input type="text" className="form-control" id="top_speed" required onChange={this.handleChange}/>
                    </div>
                    <div className="col-md-6">
                        <label for="cost" className="form-label">Cost</label>
                        <input type="text" className="form-control" id="cost" required onChange={this.handleChange}/>
                    </div>
                    <div className="col-md-6">
                        <label for="sales_units" className="form-label">Sales unit in FY20-21</label>
                        <input type="text" className="form-control" id="sales_units" required onChange={this.handleChange}/>
                    </div>   
                    <button type="submit" className="btn btn-info col-md-4 offset-md-4 justify-content-center">Login</button>
                </form>
            </div>
        )
    }
}

const mapDispatchToProps = (dispatch) =>{   
    return{   
        addVechile: (vechile) =>{ dispatch({type: 'ADD_VECHILE', vechile})}
    }
}

 export default connect(null,mapDispatchToProps)(Add)

Vechile.js：

import React, { Component } from 'react'
import {connect} from 'react-redux'

class Vechile extends Component {

    render() {
        console.log(this.props.vechile)
        const vechile =this.props.vechile ? (
            <div>
                <h4>Model Name: {this.props.vechile.model_name}</h4>
                <h4>Vechile Type: {this.props.vechile.vehchile_type}</h4>
                <h4>Mileage: {this.props.vechile.mileage}</h4>
                <h4>Top Speed: {this.props.vechile.top_speed}</h4>
                <h4>Cost: {this.props.vechile.cost}</h4>
                <h4>Sales in unit for FY20-21: {this.props.vechile.sales_units}</h4>
            </div>
        ):(
            <div>Loading Data....</div>
        )
        return (
            <div>
                <span>{vechile}</span>
            </div>
        )
    }
}

const mapStateToProps=(state,ownProps)=>{
    console.log(state,ownProps)
    let id= ownProps.match.params.id;
    console.log(id)
    return{
        vechile: state.vechileInfo.find(vechile=>{
            return vechile.id===id
        })
    }
}
export default connect(mapStateToProps)(Vechile)

Answer 1

问题

添加新车辆时，您导航到"/View" ，而不是包含车辆 ID 的路径，例如"/1234" 。 我怀疑这里发生的是您的路由器只有一个"/view"路径，而不是"/View" ，因此在交换机匹配并呈现您的动态"/:id"并且为id分配值"View" ，它可能与任何已保存的车辆id属性都不匹配。

在Vechile组件中，注入的vechile只是未定义，因此呈现"Loading Data...." 。

const mapStateToProps=(state,ownProps)=>{
    let id= ownProps.match.params.id;
    return{
        vechile: state.vechileInfo.find(vechile=>{
            return vechile.id === id // <-- vechile.id === "View" is false
        })
    }
}

解决方案

如果您想导航到车辆详细信息页面，请在Add组件中修复导航。 您首先需要添加或生成一个id属性，然后导航到正确的路径。

import React, { Component } from 'react';
import { connect } from "react-redux";
import { v4 as uuidV4 } from 'uuid';

class Add extends Component {
  state={   
    model_name:'',
    vehchile_type:'',
    mileage:'',
    top_speed:'',
    cost:'',
    sales_units:''
  }

  handleChange = (e) => {
    this.setState({
      [e.target.id]: e.target.value
    })
  }

  handleSubmit=(e)=>{
    e.preventDefault();
    const newId = uuidV4(); // <-- generate new id
    this.props.addVechile({
      ...this.state,
      id: newId, // <-- add id to new vehicle object
    });
    this.props.history.push(`/${newId}`); // <-- navigate to generic path with id
  }

如果您想导航到“/view”路径，那么您仍然需要创建一个具有id属性的新车辆 object，但只需指向正确的路径。

...

handleSubmit=(e)=>{
  e.preventDefault();
  const newId = uuidV4();
  this.props.addVechile({
    ...this.state,
    id: newId,
  });
  this.props.history.push(`/view`); // <-- navigate to "/view" instead of "/View"
}