我目前正在构建一个聊天应用程序，我遇到了Firebase规则的问题。我想限制用户查看他们不参与的对话。但是，当我尝试实施规则时，似乎即使在检查对话是否存在时也会拒绝访问。我如何正确配置Firebase规则以允许用户仅查看他们参与的对话，而不是数据库里的所有对话

这是规则集，我试图只为对话实现。

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {
    
    // Allow users to read and write their own participant documents
    match /conversation/{conversationId}/participants/{userId} {
      allow read, write: if request.auth.uid == userId;
    }

    // Allow users to read and write messages in a conversation they are a participant of
    match /conversation/{conversationId}/messages/{messageId} {
      allow read, write: if exists(/databases/$(database)/documents/conversation/$(conversationId)/participants/$(request.auth.uid));
    }

    // Allow users to read and write their own conversation documents
    match /conversation/{conversationId} {
      allow read, write: if exists(/databases/$(database)/documents/conversation/$(conversationId)/participants/$(request.auth.uid));
    }
  }
}

访问已经在“最高级别”被拒绝，这是这里的这一部分：

// Allow users to read and write their own conversation documents
    match /conversation/{conversationId} {
      allow read, write: if exists(/databases/$(database)/documents/conversation/$(conversationId)/participants/$(request.auth.uid));
    }

我假设，这与方式有关，这些嵌套的对话正在工作，但我不知道我必须改变什么.我试着在谷歌firebase文档中阅读有关此，但我找不到任何关于这一点.如果你有任何想法，如何解决这个问题，请让我知道.谢谢！
我已经试过让它在多个“规则集”下工作。它总是在exists（）-函数处失败。
我也试过这个，但似乎也不行：

rules_version = '2';
service cloud.firestore {
  match /databases/{database}/documents {

    function isUserInParticipants(conversationId) {
      return get(/databases/$(database)/documents/conversations/$(conversationId)/participants/$(request.auth.uid)).data != null;
    }

    match /conversations/{conversationId} {
      allow read, write: if request.auth != null && isUserInParticipants(conversationId);

      match /messages/{messageId} {
        allow read, write: if request.auth != null && isUserInParticipants(conversationId);
      }
    }
  }
}

这是我在Vue.js中使用的查询：

init() {
      const storeAuth = useStoreAuth();
      conversationCollectionRef = collection(db, 'conversation')
      conversationCollectionQuery = query(conversationCollectionRef) 
      this.getConversations()
    },
    async getConversations() {
      this.coversationsLoaded = false
      getConversationSnapshot = onSnapshot(conversationCollectionQuery, (snapshot) => {
        console.log('getConversations')
        console.log(snapshot)
        this.conversations = []
        snapshot.forEach((doc) => {
          this.getMessagesOfConversation(doc.id)
          const conversation = {
            id: doc.id,
            ...doc.data(),
          }
          this.conversations.push(conversation)
        })
      })
      this.coversationsLoaded = true
    },