错误：发送 node.js 后无法设置标头

Question

hi guys im fairly new to node.js and I was wonder if I am making a call twice that I am unaware of. I am getting a Error: Can't set headers after they are sent.

export const hearingReminder = functions.https.onRequest((request, response) => {
    console.log(request.body)

    const payload = {
        notification: {
            title: 'Upcoming Hearing',
            body: 'You have a hearing in one hour.',

        }
    };
    const fcm = request.body.fcm
    console.log(request.body.fcm)

    try {

        response.status(200).send('Task Completed');
        return admin.messaging().sendToDevice(fcm, payload);
    } catch (error) {

        return response.status(error.code).send(error.message);

    }

Answer 1

Your code is attempting to send a response twice, under the condition that admin.messaging().sendToDevice generates an error. Instead of sending the 200 response before the call, only send it after the call. Sending the response should always be the very last thing performed in your function.

Your code should be more like this:

    admin.messaging().sendToDevice(fcm, payload)
    .then(() => {
        response.status(200).send('Task Completed');
    })
    .catch(error => {
        response.status(error.code).send(error.message);
    })

Note that you don't need to return anything for HTTP type functions. You just need to make sure to handle all the promises, and only send the response after all the promises are resolved.