Reactjs I'；我正在寻找一个类型错误的原因，在一个来自reducer的成功请求之后

我不知道为什么我在减速器上出错

减速机代码

        case ADD_COMMENT_SUCCESS: {
            const postIndex = state.mainPosts.findIndex(v => v.id === action.data.postId);
            const post = state.mainPosts[postIndex];
            const Comments = [...post.Comments, action.data.comment];
            const mainPosts = [...state.mainPosts];
            mainPosts[postIndex] = { ...post, Comments };
            return {
                ...state,
                isAddingComment: false,
                mainPosts,
                commentAdded: true,
            };
        }

此文件中出现错误

const Comments = [...post.Comments, action.data.comment];

吉特：

---

感谢您让我知道如何修复它

我想这是因为

findIndex

在

id

s不匹配的情况下返回

undefined

，这会导致类似

undefined.Comments

的内容，从而引发错误

        case ADD_COMMENT_SUCCESS: {
            const postIndex = state.mainPosts.findIndex(v => v.id === action.data.postId);
            if(postIndex){
               const post = state.mainPosts[postIndex];
               const Comments = [...post.Comments, action.data.comment];
               const mainPosts = [...state.mainPosts];
                mainPosts[postIndex] = { ...post, Comments };
                return {
                  ...state,
                  isAddingComment: false,
                  mainPosts,
                  commentAdded: true,
                };
             }
              else{
              // Write Your logic if the index is not found
              return state;

        }

---

请检查

post.Comments

，如果它不是数组，将引发异常。