Question

我的应用中有以下状态：

    const [activeChats, setActiveChats] = useState([
        {
          id: 1,
          name: 'Luciana Gutierrez',
          role: 'HR Manager',
          avatar: avatar2,
          messages: [
            {
              content: 'Hola Luciana! Tuviste alguna novedad?',
              received: false,
              date: '9:45 AM'
            },
            {
              content: 'Hola John! Todavía no...',
              received: true,
              date: '10:19 AM'
            },
            {
              content: 'Si tengo alguna otra novedad te comento. Gracias!',
              received: true,
              date: '10:20 AM'
            }
          ]
        },
        {
          id: 2,
          name: 'Micaela Alvarez',
          role: 'Marketing Manager',
          avatar: avatar1,
          messages: [
            {
              content: 'Hola John! Entre qué horarios podrías hoy tener la meeting?',
              received: true,
              date: '9:45 AM'
            },
            {
              content: 'Hola Micaela! Muy bien. Yo puedo de 10 a 17 hs.',
              received: false,
              date: '10:05 AM'
            },
            {
              content: 'Dale, agendé la meeting para hoy a las 14hs.',
              received: true,
              date: '10:15 AM'
            }
          ]
        },
        {
          id: 3,
          name: 'Manuel Hoffman',
          role: 'Business Manager',
          avatar: avatar3,
          messages: [
            {
              content: 'Gracias por la reunión de ayer, Manu, fue muy productiva!',
              received: false,
              date: '9:35 AM'
            },
            {
              content: 'Gracias a vos!',
              received: true,
              date: '9:37 AM'
            }
          ]
        }
      ])

而且我只想通过在每个对象的消息键中添加更多项来修改它，而保持其余状态不变。

例如，假设我向第一个对象添加了两条新消息。状态应如下所示：

const [activeChats, setActiveChats] = useState([
    {
      id: 1,
      name: 'Luciana Gutierrez',
      role: 'HR Manager',
      avatar: avatar2,
      messages: [
        {
          content: 'Hola Luciana! Tuviste alguna novedad?',
          received: false,
          date: '9:45 AM'
        },
        {
          content: 'Hola John! Todavía no...',
          received: true,
          date: '10:19 AM'
        },
        {
          content: 'Si tengo alguna otra novedad te comento. Gracias!',
          received: true,
          date: '10:20 AM'
        },
        {
          content: 'Example1',
          received: true,
          date: '10:21 AM'
        },
        {
          content: 'Example2',
          received: true,
          date: '10:22 AM'
        }
      ]
    },
    {
      id: 2,
      name: 'Micaela Alvarez',
      role: 'Marketing Manager',
      avatar: avatar1,
      messages: [
        {
          content: 'Hola John! Entre qué horarios podrías hoy tener la meeting?',
          received: true,
          date: '9:45 AM'
        },
        {
          content: 'Hola Micaela! Muy bien. Yo puedo de 10 a 17 hs.',
          received: false,
          date: '10:05 AM'
        },
        {
          content: 'Dale, agendé la meeting para hoy a las 14hs.',
          received: true,
          date: '10:15 AM'
        }
      ]
    },
    {
      id: 3,
      name: 'Manuel Hoffman',
      role: 'Business Manager',
      avatar: avatar3,
      messages: [
        {
          content: 'Gracias por la reunión de ayer, Manu, fue muy productiva!',
          received: false,
          date: '9:35 AM'
        },
        {
          content: 'Gracias a vos!',
          received: true,
          date: '9:37 AM'
        }
      ]
    }
  ])

我该怎么做？我正在考虑扩展运算符，但我不确定如何将它与我拥有的嵌套一起使用。

Answer 1

您需要为 setActiveStates 返回一个新数组，特别注意不要改变您正在更新的嵌套对象。一种长期的方法是对要更新的项目的 findIndex()，然后将此索引用于相关项目之前和之后的数组的 spread slice()，并且还检索和克隆项目本身和任何嵌套的对象属性以返回副本。

const newMessages = [{ content: 'new1', received: true, date: '10:21 AM' }, { content: 'new2', received: true, date: '10:22 AM' }];
const itemId = 1;

setActiveChats(prevState => {
  const index = prevState.findIndex(({ id }) => id = itemId);
  const item = prevState[index];
  return [
    ...prevState.slice(0, index),
    { ...item, messages: [...item.messages, ...newMessages] },
    ...prevState.slice(index + 1)
  ];
});

Answer 2

使用嵌套结构执行此操作有点乏味，但应该可以：

    setActiveChats(
      activeChats.map((activeChat, idx) => {
        // Add to the first entry
        if (idx === 0) {
          return {
            ...activeChat,
            // assumes `newMessages` is an array of new messages
            messages: [...activeChat.messages, ...newMessages]
          };
        }
        return activeChat;
      })
    );

查看完整的工作示例 here。

如何在反应组件状态下修改对象内的数组

2 个答案: