如何使用Firebase中的Dialogflow实现来获取数据

Question

I'm currently working on a FAQ chatbot.
Some of the answers will be specific depending on the parameter of the user, so I decided to use Webhook so I can fetch response from my firebase database.

After some research, I've noticed that Dialogflow works asynchronously and I had to use Promise, but I'm still not able to make the response dynamic and synchronous.

Here's my code:

    function fetch_data(param)
    {
        return function(agent)
        {
            console.log("Fetching informations ...");
            var result = database_call();

            result.then(function(response)
            {
                agent.add(response);
            });
            agent.add("Timeout !")
        };
    }

    function database_call()
    {
        return new Promise((resolve, reject) => {
            var ref = db.ref("test/");
            var refTest = ref.child('test');
            refTest.on("value", function(snapshot)
            {
                console.log(snapshot.val());
                resolve(snapshot.val());
            });
            agent.add("[TIMEOUT] Cannot fetch data !")
        });
    }

I always get the message: Cannot fetch data, despite the Promise function.
On my log, I notice that the data are always printed few seconds after the "timeout" message.

Answer 1

Because it is async it will always print the timeout.

Move the timeouts to the fail case for the ref test.

refTest.on("value", function(snapshot)
{
  console.log(snapshot.val());
  resolve(snapshot.val());
});

refTest.on("error", function(snapshot)
{
  agent.add("[TIMEOUT] Cannot fetch data !")
  reject();
});

Then you can catch the error.

result.then(function(response)
{
  agent.add(response);
}).catch(() => {
  agent.add("Timeout !")
});