如何获取Firestore文档中的字段? [英] How to get fields in a firestore document?

问题描述

我正在使用与Firestore配合使用的某些Cloud函数.我正在尝试获取特定文档的字段列表.例如，我有一个来自even.data.ref的文档参考，但是我不确定该文档是否包含我正在查看的字段.我想获取字段名称的列表，但是我不确定该怎么做. 我试图使用Object.keys()方法来获取数据键的列表，但是我只得到数字列表(0，1 ...)，而不是字段名称.
我尝试使用documentSnapShot.contains()方法，但似乎不起作用.

I am working on some Cloud functions that works with Firestore. I am trying to get a list of fields of a specific document. For example, I have a document reference from the even.data.ref, but I am not sure if the document contains the field I am looking at. I want to get a list of the fields' name, but I am not sure how to do it. I was trying to use Object.keys() method to get a list of keys of the data, but I only get a list of number (0, 1...), instead of name of fields.
I tried to use the documentSnapShot.contains() method, but it seems doesn't work.

exports.tryHasChild=functions.firestore.document('cities/{newCityId}')
.onWrite((event) =>{
  if (event.data.exists) {
    let myRef = event.data.ref;
    myRef.get().then(docSnapShot => {
      if (docSnapShot.contains('population')) {
        console.log("The edited document has a field of population");
      }
    });

推荐答案

作为文档将Cloud Firestore触发器用于Cloud Functions 显示后，您可以使用event.data.data()获取文档的数据.

As the documentation on using Cloud Firestore triggers for Cloud Functions shows, you get the data of the document with event.data.data().

然后，您可以使用JavaScript的Object.keys()方法遍历字段名称，或通过简单的数组检查来测试数据是否包含字段:

Then you can iterate over the field names with JavaScript's Object.keys() method or test if the data has a field with a simple array check:

exports.tryHasChild=functions.firestore.document('cities/{newCityId}')
.onWrite((event) =>{
  if (event.data.exists) {
    let data = event.data.data();
    Object.keys(data).forEach((name) => {
      console.log(name, data[name]);
    });
    if (data["population"]) {
      console.log("The edited document has a field of population");
    }
});

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