Question

我正在制作一个小的食谱清单，用于React的学习目的（因为我是新手）。

我能够从列表中弄清楚如何添加和删除食谱。但是我很难从列表中编辑配方（App的状态）。

关注Redux的文档：

因为我们想要更新数组中的特定项目采用突变，我们必须创建一个相同的新阵列除了索引处的项目之外的项目。

我很难在修改自己选择的数组时选择数组中的特定项目。

这是我的动作文件：

的src /操作

export const RECIPE_ADD = 'RECIPE_ADD';
export const RECIPE_EDIT = 'RECIPE_EDIT';
export const RECIPE_DELETE = 'RECIPE_DELETE';
export function addRecipe(recipe) {
  return {
    type: RECIPE_ADD,
    payload: recipe
  }
}
export function editRecipe(recipe) {
  return {
    type: RECIPE_EDIT,
    payload: recipe
  }
}
export function deleteRecipe(recipe) {
  return {
    type: RECIPE_DELETE,
    payload: recipe
  }
}

的src /减速器/ reducer_recipe

import { RECIPE_ADD } from '../actions/index';
import { RECIPE_DELETE } from '../actions/index';
import { RECIPE_EDIT } from '../actions/index'

const defaultList = [
  { recipe: 'Pizza', ingredients: ['tomato-sauce','cheese','peperoni'] },
  { recipe: 'Pie', ingredients: ['dough','cherry'] },
  { recipe: 'Curry', ingredients: ['rice','sauce','carrots'] },
];

export default function(state = defaultList, action){
  switch (action.type) {
    case RECIPE_ADD:
      return [
        { recipe: action.payload[0], ingredients: action.payload[1] },
        ...state
      ];
    case RECIPE_DELETE:
    let index = state.map(x => x.recipe).indexOf(action.payload.recipe)
      return (
        state.slice(0,index).concat(state.slice(index + 1))
      )
    case RECIPE_EDIT:
    console.log(action.payload)
    // action.payload is the updated selected recipe
      return (
        state
      )
  }
  return state;
}

我怀疑我需要在动作中添加一个id来区分它与数组列表？

Answer 1

您应该在defaultList中添加一个id：

const defaultList = [
  { id: 1, recipe: 'Pizza', ingredients: ['tomato-sauce','cheese','peperoni'] },
  { id: 2, recipe: 'Pie', ingredients: ['dough','cherry'] },
  { id: 3, recipe: 'Curry', ingredients: ['rice','sauce','carrots'] },
];

然后更新您的食谱：

    case RECIPE_EDIT:
      return state.map((recipe)=> {
        if( recipe.id == action.payload.id ) {
          return action.payload
        } else {
          return recipe;
        }
      });

只有当您确定===和==都是整数时，才应使用recipe.id而不是action.payload.id。

Answer 2

也许这样的事情可以发挥作用：

import { RECIPE_ADD } from '../actions/index';
import { RECIPE_DELETE } from '../actions/index';
import { RECIPE_EDIT } from '../actions/index'

const defaultList = [
  { recipe: 'Pizza', ingredients: ['tomato-sauce','cheese','peperoni'] },
  { recipe: 'Pie', ingredients: ['dough','cherry'] },
  { recipe: 'Curry', ingredients: ['rice','sauce','carrots'] },
];

export default function(state = defaultList, action){
  switch (action.type) {
    case RECIPE_ADD:
      return [
        { recipe: action.payload[0], ingredients: action.payload[1] },
        ...state
      ];
    case RECIPE_DELETE:
      let index = state.map(x => x.recipe).indexOf(action.payload.recipe)
        return (
          state.slice(0,index).concat(state.slice(index + 1))
        )
    case RECIPE_EDIT:
      return state.map((recipe)=> {
        if( recipe.name === action.payload.name ) {
          return action.payload
        } else {
          return recipe;
        }
        return recipe;
      });
  }
  return state;
}

通过Redux的Reducer更新列表

2 个答案: