如何在 ReactJS 中使用 Map 访问嵌套对象

Question

I'm quite new to react JS, I need to access the selected nested object using the map method in reactJS. I need the output as below screenshot.please someone help me on this.

DishdetailComponent.js | File

import {
    Card,
    CardImg,
    CardImgOverlay,
    CardText,
    CardBody,
    CardTitle
} from 'reactstrap';

class DishDetail  extends Component{
constructor(props){
        super(props);

        this.state = {
            selectedDish: null
        }
    };

    onDishSelect(dish){
        this.setState({selectedDish: dish})
    }

    renderDish(dish) {
        if (dish != null)
            return(
                <Card>
                    <CardImg top src={dish.image} alt={dish.name} />
                    <CardBody>
                      <CardTitle>{dish.name}</CardTitle>
                      <CardText>{dish.description}</CardText>
                    </CardBody>
                </Card>
            );
        else
            return(
                <div></div>
            );
    }

    renderComments(dish){
        if (dish != null)
            return(
                <Card key={dish.comments.id}
                  onClick={() => this.onDishSelect(dish)}>
                    <CardBody>
                      <CardTitle>Comments</CardTitle>
                      <CardText key={dish.comments.id}>{dish.comments.map((sup)=> sup.comment)}</CardText>
                      <CardText>{dish.comments.map((sup)=> sup.author)}</CardText>
                    </CardBody>
                </Card>
            );
        else
            return(
                <div></div>
            );
    }

    render() {
        const menu = this.props.dishes.map((dish) => {
            return (
                <div  className="col-12 col-md-5 m-1">
                <Card key={dish.id}
                  onClick={() => this.onDishSelect(dish)}>
                  <CardImg width="100%" src={dish.image} alt={dish.name} />
                  <CardImgOverlay>
                      <CardTitle>{dish.name}</CardTitle>
                  </CardImgOverlay>
                </Card>
              </div>
            );
        });

        return (
            <div className="container">
            <div className="row">
                {menu}
            </div>
            <div className="row">
              <div  className="col-12 col-md-5 m-1">
                {this.renderDish(this.state.selectedDish)}
              </div>
              <div  className="col-12 col-md-5 m-1">
                {this.renderComments(this.state.selectedDish)}
              </div>
            </div>
        </div>
        );
    }
}

export default  DishDetail;

dishes.js | File

    [
        {
        id: 0,
        name:'Uthappizza',
        image: 'assets/images/uthappizza.png',
        category: 'mains',
        label:'Hot',
        price:'4.99',
        description:'A unique combination of Indian Uthappam (pancake) and Italian pizza, topped with Cerignola olives, ripe vine cherry tomatoes, Vidalia onion, Guntur chillies and Buffalo Paneer.',
        comments: [
            {
            id: 0,
            rating: 5,
            comment: "Imagine all the eatables, living in conFusion!",
            author: "John Lemon",
            date: "2012-10-16T17:57:28.556094Z"
            },
            {
            id: 1,
            rating: 4,
            comment: "Sends anyone to heaven, I wish I could get my mother-in-law to eat it!",
            author: "Paul McVites",
            date: "2014-09-05T17:57:28.556094Z"
            },
            {
            id: 2,
            rating: 3,
            comment: "Eat it, just eat it!",
            author: "Michael Jaikishan",
            date: "2015-02-13T17:57:28.556094Z"
            },
            {
            id: 3,
            rating: 4,
            comment: "Ultimate, Reaching for the stars!",
            author: "Ringo Starry",
            date: "2013-12-02T17:57:28.556094Z"
            },
            {
            id: 4,
            rating: 2,
            comment: "It's your birthday, we're gonna party!",
            author: "25 Cent",
            date: "2011-12-02T17:57:28.556094Z"
            }
        ]                        },
        {
        id: 1,
        name:'Zucchipakoda',
        image: 'assets/images/zucchipakoda.png',
        category: 'appetizer',
        label:'',
        price:'1.99',
        description:'Deep fried Zucchini coated with mildly spiced Chickpea flour batter accompanied with a sweet-tangy tamarind sauce',
        comments: [
            {
            id: 0,
            rating: 5,
            comment: "Imagine all the eatables, living in conFusion!",
            author: "John Lemon",
            date: "2012-10-16T17:57:28.556094Z"
            },
            {
            id: 1,
            rating: 4,
            comment: "Sends anyone to heaven, I wish I could get my mother-in-law to eat it!",
            author: "Paul McVites",
            date: "2014-09-05T17:57:28.556094Z"
            },
            {
            id: 2,
            rating: 3,
            comment: "Eat it, just eat it!",
            author: "Michael Jaikishan",
            date: "2015-02-13T17:57:28.556094Z"
            },
            {
            id: 3,
            rating: 4,
            comment: "Ultimate, Reaching for the stars!",
            author: "Ringo Starry",
            date: "2013-12-02T17:57:28.556094Z"
            },
            {
            id: 4,
            rating: 2,
            comment: "It's your birthday, we're gonna party!",
            author: "25 Cent",
            date: "2011-12-02T17:57:28.556094Z"
            }
        ]
        },
        {
        id: 2,
        name:'Vadonut',
        image: 'assets/images/vadonut.png',
        category: 'appetizer',
        label:'New',
        price:'1.99',
        description:'A quintessential ConFusion experience, is it a vada or is it a donut?',
        comments: [
            {
            id: 0,
            rating: 5,
            comment: "Imagine all the eatables, living in conFusion!",
            author: "John Lemon",
            date: "2012-10-16T17:57:28.556094Z"
            },
            {
            id: 1,
            rating: 4,
            comment: "Sends anyone to heaven, I wish I could get my mother-in-law to eat it!",
            author: "Paul McVites",
            date: "2014-09-05T17:57:28.556094Z"
            },
            {
            id: 2,
            rating: 3,
            comment: "Eat it, just eat it!",
            author: "Michael Jaikishan",
            date: "2015-02-13T17:57:28.556094Z"
            },
            {
            id: 3,
            rating: 4,
            comment: "Ultimate, Reaching for the stars!",
            author: "Ringo Starry",
            date: "2013-12-02T17:57:28.556094Z"
            },
            {
            id: 4,
            rating: 2,
            comment: "It's your birthday, we're gonna party!",
            author: "25 Cent",
            date: "2011-12-02T17:57:28.556094Z"
            }
        ]
        },
        {
        id: 3,
        name:'ElaiCheese Cake',
        image: 'assets/images/elaicheesecake.png',
        category: 'dessert',
        label:'',
        price:'2.99',
        description:'A delectable, semi-sweet New York Style Cheese Cake, with Graham cracker crust and spiced with Indian cardamoms',
        comments: [
            {
            id: 0,
            rating: 5,
            comment: "Imagine all the eatables, living in conFusion!",
            author: "John Lemon",
            date: "2012-10-16T17:57:28.556094Z"
            },
            {
            id: 1,
            rating: 4,
            comment: "Sends anyone to heaven, I wish I could get my mother-in-law to eat it!",
            author: "Paul McVites",
            date: "2014-09-05T17:57:28.556094Z"
            },
            {
            id: 2,
            rating: 3,
            comment: "Eat it, just eat it!",
            author: "Michael Jaikishan",
            date: "2015-02-13T17:57:28.556094Z"
            },
            {
            id: 3,
            rating: 4,
            comment: "Ultimate, Reaching for the stars!",
            author: "Ringo Starry",
            date: "2013-12-02T17:57:28.556094Z"
            },
            {
            id: 4,
            rating: 2,
            comment: "It's your birthday, we're gonna party!",
            author: "25 Cent",
            date: "2011-12-02T17:57:28.556094Z"
            }
        ]
        }
    ];

App.js | File

import React, { Component } from 'react';
import './App.css';
import { Navbar, NavbarBrand } from 'reactstrap';

import Menu from './components/MenuComponent';
import DishDetail from './components/DishdetailComponent';

import { DISHES } from './shared/dishes';

class App extends Component {

  constructor(props){
    super(props);

    this.state = {
      dishes: DISHES
    };
  }

  render(){
    return(
      <div>
        <Navbar dark color="primary">
            <div className="container">
              <NavbarBrand href="/">Ristorante Con Fusion</NavbarBrand>
            </div>
        </Navbar>
        <DishDetail dishes={this.state.dishes}/>
        {/* <Menu dishes={this.state.dishes} /> */}
      </div>
    );
  }
}

export default App;

to have better understand please refer below link
https://noorzee.github.io/confusion/

Answer 1

If i understand the question correctly, you want to show all comments for each product.

CodeSandbox

Explanation

Given the fact that comments is an array, you assumed correctly that you need to use map .

map invokes on an array and return the result of a callback on each item.

We know that each comment looks like this

 {
        id: 0,
        rating: 5,
        comment: "Imagine all the eatables, living in conFusion!",
        author: "John Lemon",
        date: "2012-10-16T17:57:28.556094Z"
 }

Meaning we need to return something similar to

 <div className="comment">
      <div>{comment.comment}</div>
      <div>{comment.author}</div>
      <div>{comment.date}</div>
 </div>

Now let's do it with map :

comments.map(function(comment) {
   return (
      <div className="comment">
        <div>{comment.comment}</div>
        <div>{comment.author}</div>
        <div>{comment.date}</div>
      </div>
  )}
)

This will produce the array:

[
 <div className="comment">
      <div>{comment1.comment}</div>
      <div>{comment1.author}</div>
      <div>{comment1.date}</div>
 </div>,
 <div className="comment">
      <div>{comment2.comment}</div>
      <div>{comment2.author}</div>
      <div>{comment2.date}</div>
 </div>,
 <div className="comment">
      <div>{comment3.comment}</div>
      <div>{comment3.author}</div>
      <div>{comment3.date}</div>
 </div>
...
]