等待时如何遍历Firestore快照文档 [英] How to iterate through a Firestore snapshot documents while awaiting

问题描述

我一直在尝试从Firestore获取一系列文档，阅读它们并根据一系列字段采取相应的行动.关键部分是我要在处理每个文档时等待特定的过程.官方文档介绍了此解决方案:

I have been trying to obtain a series of documents from firestore, reading them and acting accordingly depending on a series of fields. The key part is I want to wait for a certain process while working on each document. The official documentation presents this solution:

const docs = await firestore.collection(...).where(...).where(...).get()
    docs.forEach(await (doc) => {
      //something
    })

当您在forEach中有一个承诺时，此解决方案的问题就解决了，它不会在继续之前等待它，而我需要它.我已经尝试过使用for循环:

The problem with this solution is taht when you have a promise inside the forEach it won't await it before continuing, which I need it to. I have tried using a for loop:

const docs = await firestore.collection(...).where(...).where(...).get()
            for(var doc of docs.docs()) {
      //something
            }

使用此代码时，Firebase会警告"docs.docs(...)不是函数，或者其返回值不可迭代".关于如何解决此问题的任何想法?

When using this code Firebase alerts that 'docs.docs(...) is not a function or its return value is not iterable'. Any ideas on how to work around this?

推荐答案

请注意，您的 docs 变量是 docs 的数组属性，您可以对其进行迭代像普通数组一样.如果这样重命名变量，将会更容易理解:

Note that your docs variable is a QuerySnapshot type object. It has an array property called docs that you can iterate like a normal array. It will be easier to understand if you rename the variable like this:

const querySnapshot = await firestore.collection(...).where(...).where(...).get()
for (const documentSnapshot of querySnapshot.docs) {
    const data = documentSnapshot.data()
    // ... work with fields of data here
    // also use await here since you are still in scope of an async function
}

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