Socket.io run function on update

Question

How do I run a function when socket.io updates a variable. It seems that $watch does not work or purhaps I am doing something wrong.

$http.get('/api/availabilitys/' + myId).then(response => {
  $scope.availability = response.data;
  socket.syncUpdates('availability', $scope.availability);
});


$scope.$watch('availability', function() {
  console.log('test'); //This is not printing on update
  angular.forEach(self.location, function (loc){
    loc.availability = $scope.availability.filter(function (a){
      return a.loc === loc._id;
    });
  });
});

in your `$http.get` after updating the values, try doing `$scope.$apply()` — laggingreflex, Mar 10 '16 at 10:58
Does not help. The test prints the first time around. It does not print on update. — Mika, Mar 10 '16 at 11:01

score 0 · Answer 1 · edited May 23 '17 at 12:15

0

The functions have to be in the same controller / scope because of encapsulation. The $scope of angular does not know if socket.io updates a variable, use a socket.on() listener to trigger the angular $watch

Try the code in this thread Socket.IO message doesn't update Angular variable

Instead of $watch in angular you can use socket.on() of socket.io

 var container = angular.module("AdminApp", []);

 container.controller("StatsController", function($scope) {

var socket = io.connect();

socket.on('message', function (msg) {
    console.log(msg);
    $scope.$apply(function() { $scope.frontEnd = msg; });
});
});

See (the posts at the end of) this thread How do I use $scope.$watch and $scope.$apply in AngularJS?

edited May 23 '17 at 12:15

Community

1
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answered Mar 10 '16 at 11:00

ralf htp

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I know how to use $watch. My question is why is my socket update not triggering the $watch. – Mika Mar 10 '16 at 11:03
The $watch should work. What does not seem to work is the socket update. The socket update is outside of the 'scope' of angular see this thread http://stackoverflow.com/questions/30976934/socket-io-message-doesnt-update-angular-variable – ralf htp Mar 10 '16 at 11:12
My socket update is working as the $scope.availability variable is updating in the UI so angular is aware of it. – Mika Mar 10 '16 at 11:16
Is the variable 'avasilibility' defined inside the scope that the $watch listens to ? this is the key point... – ralf htp Mar 10 '16 at 11:30
Yes it is setup in the same scope. – Mika Mar 10 '16 at 11:33
try the socket.on() listener above. Maybe there has first to be executed a listener that triggers the $watch / $digest at all. See the last post of this thread http://stackoverflow.com/questions/15112584/using-scope-watch-and-scope-apply-in-angularjs – ralf htp Mar 10 '16 at 11:49

Socket.io run function on update

1 Answers1