觸發雲函數時“類型錯誤：無法讀取未定義的屬性‘子’”

Question

我有一個雲函數，每當有新消息寫入與該用戶關聯的數據庫時，它都會向接收器發送通知。 我似乎不斷收到錯誤。

我是雲功能的新手，似乎無法解決這個問題。

看下面的雲功能

exports.sendNotification = functions.database.ref('/messages/{userId}/{messageId}')
.onWrite((snapshot,context) => {
    
    //get the userId of the person receiving the notification because we need to get their token
    const receiverId = context.params.userId;
    console.log("receiverId: ", receiverId);
    
    //get the user id of the person who sent the message
    //const senderId = context.data.child('senderUid').val();
    const senderId = snapshot.data.child('senderUid').val();
    console.log("senderId: ", senderId);
    
    //get the message
    const message = snapshot.data.child('messageBody').val();
    console.log("message: ", message);
    
    //get the message id. We'll be sending this in the payload
    const messageId = context.params.messageId;
    //const messageId = event.params.messageId;
    console.log("messageId: ", messageId);
    
    //query the users node and get the name of the user who sent the message
    return admin.database().ref("/Renters/" + senderId).once('value').then(snap => {
        const senderName = snap.child("houseName").val();
        console.log("senderName: ", senderName);
        
        //get the token of the user receiving the message
        return admin.database().ref("/users/" + receiverId).once('value').then(snap => {
      //const token = snap.child("messaging_token").val();
      const token = event.data.child('receiverToken').val();
            console.log("token: ", token);
            
            //we have everything we need
            //Build the message payload and send the message
            console.log("Construction the notification message.");
            const payload = {
                data: {
                    data_type: "direct_message",
                    title: "New Message from " + senderName,
                    message: message,
                    message_id: messageId,
                }
            };
            
            return admin.messaging().sendToDevice(token, payload)
                        .then(function(response) {
              console.log("Successfully sent message:", response);
              //using this return statement to avoid error
              return response.successCount;
                          })
                          .catch(function(error) {
                            console.log("Error sending message:", error);
                          });
        });
    });
});

Answer 1

我已經做了一些測試，並且文檔中DataSnapshot對象中沒有屬性data 。 由於這個調用，它將給出undefined值。 因此，如果您對此進行任何調用，則會導致此類錯誤。

如果您將...snapshot.data.child('senderUid').val()...更改為：

...snapshot.child('senderUid').val()...

不確定您為什么在此處添加此data ，但是即使您在引用的路徑中有名為“data”的子項，它也不起作用。