Question

我有一个包含属性addon_categories的对象数组id和另一个数组addons。当用户切换复选框时，状态应相应更新：包括在所选类别下添加或删除“插件”数组。

this.state = { addon_categories: [] };

// example of filled state
this.state = { addon_categories: [
     { id: 3, addons: [ 1 ] },
     { id: 2, addons: [ 1, 4, 11 ] },
     { id: 4, addons: [ 3, 4] }
 ] };

除了必须最终将数据更新为组件状态之外，这更多是JavaScript超过React的问题。作为JavaScript的初学者，我无法使用包含某些属性和数组的对象数组更新状态对象。在下面的代码中，为特定类别更新addons数组（对于删除和推送）的正确逻辑是什么？

这是逻辑：

如果类别ID不存在，只需添加一个类别为id的新对象和一个带有单个插件ID的插件数组。 [✓]
如果存在类别ID，则 - ＆GT;检查此类别中是否存在addon_id。
- ＆GT;如果此类别中存在addon_id，请从此对象[？]中删除此addons数组中的插件ID - ＆GT;如果addon_id不存在，请将此插件ID添加到此对象中的此插件数组中[？]

这是我的代码。

import React from 'react';
import { connect } from 'react-redux';
import store from '../../../../reducers/store';
import fetchFood from '../../../../actions/restaurant/food_get';

class AddonsModal extends React.Component
{
    constructor(props)
    {
        super(props);
        this.state = { addon_categories: [] };

        this.onAddonChange = this.onAddonChange.bind(this);
    }

    /*
     * Handle click, toggle addon change
     */
    onAddonChange(e)
    {
        const c = +e.target.name; // category_id from input
        const a = +e.target.id;   // addon_id from input

        // create new instance of this.state.addon_categories
        let addon_categories = this.state.addon_categories.slice();

        if (!this.addonCategoryExists(c))
        {
            // CATEGORY DOESNT EXIST, SO NEW CATEGORY AND ADDON ADDED!
            addon_categories.push({ id: c, addons: [a] });
            this.setState({ addon_categories }, () => console.log('NEW STATE', this.state.addon_categories));
        }
        else
        {
            // CATEGORY EXISTS
            if (this.addonExistsInCategory(c, a))
            {
                // ？？ ADDON EXISTS IN THIS CATEGORY, SO NEED TO REMOVE IT
            }
            else
            {
                // ？？ ADDON DOESNT EXIST IN CATEGORY SO NEED TO ADD IT TO JUST THIS CATEGORY
            }
        }

    }

    addonCategoryExists(c)
    {
        return !! this.state.addon_categories.filter(category => category.id === c).length;
    }

    addonExistsInCategory(c, a)
    {
        let verified = false;
        let categories = this.state.addon_categories.filter(category => category.id === c);
        categories.forEach(category =>
        {
            if (category.addons.includes(a)) { verified = true; }
        });
        return verified;
    }

    componentDidMount()
    {
        store.dispatch(fetchFood(this.props.Restaurant.id, this.props.food.id));
    }

    render()
    {
        let food = this.props.food;
        let foodData = this.props.foodDetails.food.data;
        let addon_categories = foodData ? foodData.data.addon_category : null;

        return (


                            <div className="row">

                                {addon_categories && addon_categories.map(category => { return (

                                    <div className="col-xs-12" key={category.id}>
                                        <div className="pop-up-dish-specials">
                                            <h2>{category.name}</h2>

                                            {category.addons && category.addons.map(addon => { return (

                                                <div  key={addon.id}>
                                                    {/* for simplicity, i've sent the category_id in name and addon_id in id property */}
                                                    <input type="checkbox" name={category.id} id={addon.id} onChange={this.onAddonChange}/>
                                                    <label htmlFor={addon.id}>{addon.name}</label>
                                                </div>

                                            )})}

                                        </div>
                                    </div>

                                )})}

                            </div>


        )
    }
}

function mapStateToProps(state)
{
    return { foodDetails: state.foodDetails }
}

export default connect(mapStateToProps)(AddonsModal);

Answer 1

    if (this.addonExistsInCategory(c, a)) {
      // ADDON EXISTS IN THIS CATEGORY, SO NEED TO REMOVE IT
      addon_categories.find(function(obj) {
        if (obj.id == c) {
          obj.addons.splice(obj.addons.indexOf(a), 1);
        }
      });
    } else {
      // ADDON DOESNT EXIST IN CATEGORY SO NEED TO ADD IT TO JUST THIS CATEGORY
      addon_categories.find(function(obj) {
        if (obj.id == c) {
          obj.addons.push(a);
        }
      });
    }
this.setState({ addon_categories }, () => console.log('NEW STATE', this.state.addon_categories));

Answer 2

如果存在addon，我会使用简单的.map和.filter，因此要删除：

const newCategories = this.state.addon_categories.map(category => {
    if (category.id === c) {
        const newAddons = category.addons.filter(addon => addon !== a);
        return { id: category.id, addons: newAddons };
    } else {
        return category;
    }        
});
this.setState({ addon_categories: newCategories });

添加它将是这样的：

const newCategories = this.state.addon_categories.map(category => {
    if (category.id === c) {
        const newAddons = category.addons.concat([a])
        return { id: category.id, addons: newAddons };
    } else {
        return category;
    }        
});
this.setState({ addon_categories: newCategories });

但这个问题可能有更好的解决办法。

如何通过从对象数组更新特定对象中的数组来更新状态？

2 个答案: