Firestore创建文档(如果不存在安全规则) [英] Firestore create document if it doesn't exist security rule

问题描述

我试图编写一条规则，如果文档ID不存在，则创建一个新文档.我的对象是:

I was trying to write a rule that if the id of the document doesn't exist, then create a new document. My object is:

Message message = new Message(userId, title, messageBody, timestamp);

，并且我正在使用 WriteBatch 创建一个新文档并对其进行更新:

and I'm using WriteBatch to create a new document and updating the same:

mWriteBatch.set(mMessageRef.document(messageId), message);

mWriteBatch.update(mMessageRef.document(mIntentMessageId), // params...);

浏览文档和此网站后，我发现如果使用 create 方法，则仅

After browsing through the docs and this site I've found out that if I use create method, it only allows to write the data if it doesn't exist.

所以我创建了一个安全规则，例如:

So I created a security rule like:

match /messages/{message} {
  allow read; 
  allow create: if isSignedIn();
  allow update, delete: if isSignedIn();
}

isSignedIn()只是一种包含 request.auth！= null 的方法.该规则失败并覆盖数据.现在我尝试了:

isSignedIn() is just a method contianing request.auth != null. This rule fails and overwrites the data. Now I tried:

match /messages/{message} {
  allow read; 
  allow create: if request.resource.id != message;
  allow update, delete: if isSignedIn();
}

这一次它也会覆盖数据，而不显示错误.

This time also it overwrites the data instead of showing an error.

我在这里做错了什么?感谢您的帮助.

What am I doing wrong here? Any help is appreciated.

更新:正如JoséDavid Aroesti在评论中所述，我必须进行更改将其保存为 exists ，并删除 update 和 delete 以使其正常工作，并且从应用程序中反映出它应该执行的操作.但是我该如何更新和删除文档?

Update: As told by José David Aroesti in the comments, I have to change it to exists and remove update and delete to work properly and from the app it's reflecting what it's suppose to do. But then how would I update and delete a document?

例如，当我在Simulator中使用以下规则时，两个规则均按预期执行，但是当我从设备进行测试时，即使存在，我也始终可以创建一个文档:

For example, when I'm using the below rules in Simulator, both are being executed as expected but when I'm testing it from the device, I'm always able to create a document even if it exists:

allow create: if !exists(/databases/$(database)/documents/messages/$(message));

allow update: if get(/databases/$(database)/documents/messages/$(message)).data.timestamp
        < request.resource.data.timestamp;

有可能吗?

推荐答案

您可以使用 exists()和 get()内置函数来验证是否文档已存在或正在访问该文档，以便您可以读取其数据.

You can use the exists() and get() built-in functions to verify if the document exists or to access the document so you can read its data.

在这种情况下，示例为:

In this case, an example would be:

match /messages/{message} {
    allow read; 
    allow create: if !exists(/databases/$(database)/documents/messages/$(request.resource.id));
}

并且可能不建议使用@creativecreatoror，因此，您不应为 update 和 delete 指定 allow 表达式，以免数据被覆盖.

And as @creativecreatorormaybenot suggested, you should not specify allow expressions for update and delete so the data cannot be overwritten.

以下是文档的链接:

https://firebase.google.com/docs/firestore/security/rules-conditions#access_other_documents

https://firebase.google.com/docs/reference/rules/rules.firestore

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