有什么方法可以从Firestore中的数组更新特定索引 [英] Is there any way to update a specific index from the array in Firestore

问题描述

有什么方法可以从Firebase/firestore中的数组更新特定索引吗?

Is there any way to update a specific index from the array in Firebase/firestore?

 export const editComment = (comment) => {
 return (dispatch, getState, { getFirebase, getFirestore }) => {
    const firestore = getFirestore();

    firestore.collection('topics').doc(comment.topicId).update({

     comments:  <--- this is array of objects


    }).then(() => {
      dispatch({ type: 'EDIT_COMMENT' })
    }).catch((error) => {
      dispatch({ type: 'EDIT_COMMENT_ERROR', error})
    })
  }
}

推荐答案

有什么方法可以从Firestore中的数组更新特定索引吗?

Is there any way to update a specific index from the array in Firestore?

不，没有！这是不可能的，因为如果要执行更新，则需要知道该特定元素的索引.在谈论Cloud Firestore阵列时，您可能会想到的事情有所不同.

No, there is not! This is not possible because if you want to perform an update, you need to know the index of that particular element. When talking about Cloud Firestore arrays, the things are different that you might think.

由于我们正在创建可在多用户环境中使用的应用程序，因此请尝试考虑如果用户想要编辑索引0处的值，而其他用户想要删除索引0处的值会发生什么情况?同时，其他用户可能希望在索引0处添加另一个项目.可以肯定的是，您最终将获得截然不同的结果，为什么不这样做，甚至会使数组超出范围异常.因此，带有数组的Firestore操作略有不同.因此，您无法执行诸如在特定索引处插入，更新或删除操作.

Because we are creating apps that can be used in a multi user environment, try to think what might happen if a user wants to edit a value at index 0, some other user wants to delete the value at index 0 and in the same time some other user might want to add another item at index 0. For sure, you'll end up having very different results and why not, get even array out of bounds exception. So Firestore actions with arrays are a little bit different. So you cannot perform actions like, insert, update or delete at a specific index.

如果这两种方法不能为您提供足够的帮助，则应获取整个文档，获取数组，对其进行修改并将其添加回数据库中.

If those two methods do not help you enough, you should get the entire document, get the array, modify it and add it back to the database.

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