使用 firebase 功能向特定设备发送消息

Question

我尝试使用 node js 和 firebase 函数向客户端设备发送特定消息。但是当我尝试执行该函数时，它返回了一条错误消息：

错误。提供给 sendToDevice() 的注册令牌必须是非空字符串或非空数组。

图片如下所示。

我猜它来自我的 JS 代码。所以我也发布了。我实际上要做的是从特定节点检索数据，以便在写入完全不同的节点时使用。所以我会在数据库截图之前发布JS代码。

exports.sendNotification8 = functions.database.ref('/Users/{user_id}/Notifications/')
    .onWrite(( change,context) =>{

    var user_id = context.params.user_id;

    // Grab the current value of what was written to the Realtime Database.
    var eventSnapshot = change.after.val();

    var device_token = admin.database().ref('/Users/{user_id}/device_token').once('value');

    return device_token.then(result => {

    var token_id = result.val();

    var str = eventSnapshot.from + " : " + eventSnapshot.message;
    console.log(eventSnapshot.from);

    var payload = {
        data: {
            name: str,
            title: eventSnapshot.from,
            click_action: "Chats"

        }
    };

    // Send a message to devices subscribed to the provided topic.
    return admin.messaging().sendToDevice(token_id, payload).then(function (response) {
            // See the MessagingTopicResponse reference documentation for the
            // contents of response.
            console.log("Successfully sent message:", response);
            return;
        })
        .catch(function (error) {
            console.log("Error sending message:", error);
        });

    });

    });

下面是我的数据库截图...

这就是我检索 device_token 节点的方式。来自将最新数据写入其通知节点的用户。请帮忙。我做错了什么？

Answer 1

哇。这是一种折磨。但它终于奏效了。我得到了类似的东西。

exports.sendNotification8 = functions.database.ref('/Users/{user_id}/Notifications/{notifications_id}')
    .onWrite((change,context) =>{

    var user_id = context.params.user_id;
    console.log(user_id);

    // Grab the current value of what was written to the Realtime Database.
    var eventSnapshot = change.after.val();

    var device_token = admin.database().ref('/Users/'+user_id+'/device_token').once('value');

    return device_token.then(result => {

    var token_id = result.val();

    console.log(token_id);

    var str = eventSnapshot.message;
    console.log(eventSnapshot.from);

    var payload = {
        data: {
            name: str,
            title: eventSnapshot.from,
            click_action: "Chats"

        }
    };

    // Send a message to devices subscribed to the provided topic.
    return admin.messaging().sendToDevice(token_id, payload).then(function (response) {
            // See the MessagingTopicResponse reference documentation for the
            // contents of response.
            console.log("Successfully sent message:", response);
            return;
        })
        .catch(function (error) {
            console.log("Error sending message:", error);
        });

    });

    });