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

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})
    })
  }
}

解决方案

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

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.

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.

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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