无法读取未定义的属性（读取 'then'）

Question

我在处理承诺方面真的很糟糕，并试图弄清楚为什么我会收到这个错误。 这就是我正在做的事情：

testFunction(user_email, email_html).then(() => {
    //Some stuff
}).catch((error) => {
    //Some other stuff
})

function testFunction(user_email, email_html) {
    if (user_email) {
        sendEmail({ recipient: user_email, subject: "Some words", body: email_html, html: true })
    } else {
        return true
    }
}

sendEmail 是 Firebase 云 function。

exports.sendEmail = functions.https.onCall((data, context) => {
    let is_html = data.html
    console.log("sendEmail is_html is ", is_html)
    let msg = {}
    if (!is_html) {
        msg = {
            to: data.recipient,
            from: 'contact@mydomain.com',
            subject: data.subject,
            text: data.body
        }
    } else {
        msg = {
            to: data.recipient,
            from: 'contact@mydomain.com',
            subject: data.subject,
            html: data.body
        }
    }
    console.log("sendEmail complete")
    return sgMail.send(msg)
});

我究竟做错了什么？

Answer 1

如果测试 function 成功执行，它会返回一个放在 () 里面的值，否则它会返回一个错误并去 catch。 因此，如果您想打印测试 function 的结果，您可以编写：

testFunction(user_email, email_html).then((res) => {
    console.log(res)
}).catch((error) => {
    console.log(error)
})

但是，如果您不关心结果，只要执行成功，您就需要 res 属性，否则您会写：

testFunction(user_email, email_html).then().catch((error) => {
    //Some other stuff
})

或者如果这不起作用，请尝试完全跳过 then 并编写：

testFunction(user_email, email_html).catch((error) => {
    //Some other stuff
})

Answer 2

I was able to solve it by using async in front of the client-side function declaration rather than the Firebase function itself, and await in front of the call to the Firebase function.