英文:

Firebase - addDoc() returns success even when no document was added

问题

新手使用Firebase。我有一个基本的React表单，接收用户的电子邮件并使用addDoc()将其发送到Firestore。

```js
import { initializeApp } from "firebase/app";
import { getFirestore } from "@firebase/firestore";

const firebaseConfig = {
  ...
};
// 初始化Firebase
export const app = initializeApp(firebaseConfig);

export const db = getFirestore(app)

const emailsCollectionRef = collection(db, "emails");

const addEmail = async (data: { email: string; }) => {
        console.log("发送数据到Firebase");
    try {    
        const result =  await addDoc(emailsCollectionRef, {email: data!.email});
        console.log("已写入文档，ID为：", result.id);

    } catch (e) {
        console.error("添加文档时出错：", e);
      }
        
    }

当我使用addDoc()传递用户的输入时，在try catch中，控制台会显示：

发送数据到Firebase
已写入文档，ID为： YFPaCvSjeBssvUAtdqSh

这很好，但如果我故意试图让它失败，比如更改emailsCollectionRef中集合的名称，例如：

const emailsCollectionRef = collection(db, "NoSuchCollection");

然后再次运行函数，我会得到相同的成功消息。

在Firebase文档中，它说addDoc()

> 返回：
>
> Promise<DocumentReference<T>>
>
> 一个Promise，解析为指向已在后端写入的新创建文档的DocumentReference（请注意，在离线时不会解析）。

在DocumentReference下面说

> DocumentReference是指向Firestore数据库中文档位置的引用，可用于写入、读取或监听该位置。引用位置的文档可能存在，也可能不存在。

如果我想要检查写入是否成功，我必须忽略DocumentReference，并在使用addDoc()后立即执行一个单独的查询，以查看该ID是否实际存在。

我的问题是，是否有一种更好的方法来检查写入是否真的成功，因为显然无法信任DocumentReference？

<details>
<summary>英文:</summary>

New to Firebase. I have a basic React form that takes a user&#39;s email and sends it to Firestore using addDoc().

import { initializeApp } from "firebase/app";
import { getFirestore } from "@firebase/firestore"

const firebaseConfig = {
...
};
// Initialize Firebase
export const app = initializeApp(firebaseConfig);

export const db = getFirestore(app)

const emailsCollectionRef = collection(db, "emails");

const addEmail = async (data: { email: string; }) => {
console.log("Sending data to firebase");
try {
const result = await addDoc(emailsCollectionRef, {email: data!.email});
console.log("Document written with ID: ", result.id);

} catch (e) {
    console.error("Error adding document: ", e);
  }
    
}

When I pass the user's input using addDoc() in a try catch I get this in the console

Sending data to firebase
Document written with ID: YFPaCvSjeBssvUAtdqSh

Which is fine, but if I purposefully try to make it fail like for example changing the name of the collection in *emailsCollectionRef* e.g.

const emailsCollectionRef = collection(db, "NoSuchCollection");

and run the function again I get the same success message.

In the Firebase docs it says that addDoc()

> Returns:
>
> Promise\<DocumentReference\<T\>\>
>
> A Promise resolved with a DocumentReference pointing to the newly created document after it has been written to the backend (Note that it won't resolve while you're offline).

and under DocumentReference it says

> A DocumentReference refers to a document location in a Firestore database and can be used to write, read, or listen to the location. **The document at the referenced location may or may not exist**.

If I want to check if the write was succesful I have to ignore DocumentReference and immediately after using addDoc() do a separate query to see if that ID actually exists.

My question is, is there a better way to check if the write was actually succesful since DocumentReference obviously cannot be trusted?

</details>


# 答案1
**得分**: 1

集合在您首次编写文档时会自动创建，因此很可能您对不存在的集合进行的`addDoc`调用实际上*创建*了该集合。

如果您想要防止这种情况发生，您可以只允许对数据库中特定已知的集合进行写入，这是通过服务器强制执行的[安全规则](https://firebase.google.com/docs/firestore/security/get-started)来实现的。在这一点上，`addDoc`返回的承诺也将被拒绝/失败。

<details>
<summary>英文:</summary>

Collections are created automatically when you write the first document to is, so quite likely your `addDoc` call with the non-existing collection actually *creates* that collection.

If you want to prevent that, you can only allow writes to specific, known collections in your database&#39;s [security rules](https://firebase.google.com/docs/firestore/security/get-started), which are enforced on the server. At that point, the promise returns by `addDoc` will also reject/fail.

</details>