Question

我需要执行2 firebase calls来从数据库中检索特定数据。 Once these promises resolve，我想用检索到的数据调用另一个函数。我怎样才能做到这一点？ .. Promise.All?

的东西

以下代码：

app.post('/testtwilio', function(req, res) {
  //save request variables
  var to_UID = req.body.to;
  var from_UID = req.body.from;
  var experience_id = req.body.exp_id;

  //Query firebase and save 'zone_id' which we need later
  firebase.database().ref('experiences').child(experience_id).once('value').then((snap) => {
    zone_id = snap.val().ZoneID;
  });

  //Query firebase and save 'from_name' which we need later
  firebase.database().ref('users').child(from_UID).once('value').then((snap) => {
    from_name = snap.val().Name;
  });

  //Once we have the two variables returned and saved
  //Call a final firebase query and a twilio function with all the recieved data
  firebase.database().ref('users').child(to_UID).once('value').then((snap) => {
    //Do something with this aggregated data now
    client.messages.create({
      //blah blah do something with the saved data that we retrieved
      var phone = snap.val().Phone;
      var msg = from_name + zone_id + from_UID + experience_id
    });
  });
});

Answer 1

是的，您可以使用$EmailFrom = $_REQUEST['email']; $SKU = $_REQUEST['sku']; $SIZE = $_REQUEST['size']; $ID = $_REQUEST['pridpr']; $EmailTo = "info@example.com"; $Subject = "Contact for Size"; $DATENOW = date('d/m/Y h:i:s a', time()); $Body = ""; $Body .= "<b>Email:</b> "; $Body .= $EmailFrom . "\r\n"; $Body .= "<br>"; $Body .= "<b>Product SKU:</b> "; $Body .= $SKU . "\n"; $Body .= "<br>"; $Body .= "<b>Product ID:</b> "; $Body .= $ID . "\n"; $Body .= "<br>"; $Body .= "<b>Product Size:</b> "; $Body .= $SIZE; $Body .= "<br>"; $Body .= "<b>Date:</b> "; $Body .= $DATENOW; $headers = "MIME-Version: 1.0" . "\n"; $headers .= "Content-type: text/html; charset=UTF-8" . "\n"; $headers .= "From: ". $EmailFrom ."" . "\n"; $success = mail($EmailTo, $Subject, $Body, $headers); if ($success){ echo '<div class="alert alert-success">Done!</div>'; $file = fopen('request-size.csv', 'a'); $data = array( array($EmailFrom, $SKU, $ID, $SIZE, $DATENOW) ); foreach ($data as $row) { fputcsv($file, $row); } fclose($file); } else{ echo '<div class="alert alert-danger">Error!</div>'; }，因为Promise.all会返回一个。

快速肮脏的例子：

once('value')

Answer 2

如果您使用的是7.6及更高版本的NodeJS，您也可以使用异步函数编写此代码，这样可以更加简单地阅读和维护

// ...

const wrap = require('express-async-wrap')

// ...
                        // need to wrap async function 
                        // to make it compatible with express
app.post('/testtwilio', wrap(async (req, res) => {
  const to_UID = req.body.to
  const from_UID = req.body.from
  const experience_id = req.body.exp_id

  const [
    snap1,
    snap2,
    snap3

  // waiting for all 3 promises
  ] = await Promise.all([
    firebase.database().ref('experiences').child(experience_id).once('value'),
    firebase.database().ref('users').child(from_UID).once('value'),
    firebase.database().ref('users').child(to_UID).once('value')
  ])

  const zone_id = snap1.val().ZoneID
  const from_name = snap2.val().Name
  const phone = snap3.val().Phone
  const msg = from_name + zone_id + from_UID + experience_id

  // ...
  client.messages.create(...)
}))

如何运行多个firebase promises然后一旦完成，执行函数

2 个答案: