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.publishUpdate( {id},[changes],[request],[options] )

Purpose

PublishUpdate updates nothing. It publishes information about the update of a model instance via websockets.

Description Accepted Data Types Required ?
1 ID of Updated Record int, string Yes
2 Updated values {} No
3 Request request object No
4 Additional Options object No

publishUpdate() emits a socket message using the model identity as the event name. The message is broadcast to all sockets subscribed to the model instance via the .subscribe model method.

The socket message is an object with the following properties:

  • id - the id attribute of the model instance
  • verb - "updated" (a string)
  • data - an object-- the attributes that were updated
  • previous - an object--if present, the previous values of the updated attributes

changes

This should be an object containing any changed attributes and their new values.

request

If this argument is included then the socket attached to that request will not receive the notification.

options.previous

If the options object contains a previous property, it is expected to be a representation of the model instance's attributes before they were updated. This may be used to determine whether or not to publish additional messages (see the options.noReverse flag below for more info).

options.noReverse

The default implementation of publishUpdate will, if options.previous is present, check whether any associated records were affected by the update, and possibly send out additional notifications. For example, if a Pet model has an owner attribute that is associated with the User model so that a user may own several pets, and the data sent with the call to publishUpdate indicates that the value of a pet's owner changed, then an additional publishAdd or publishRemove call may be made. To suppress these notifications, set the options.noReverse flag to true. In general, you should not have to set this flag unless you are writing your own implementation of publishUpdate for a model.

Example Usage

UsersController.js

module.exports = {

  testSocket: function(req,res){

        var nameSent = req.param('name');

        if (nameSent && req.isSocket){

          User.update({name:nameSent},{name:'Heisenberg'}).exec(function update(err,updated){
            User.publishUpdate(updated[0].id,{ name:updated[0].name });
          });

        } else if (req.isSocket){

        User.find({}).exec(function(e,listOfUsers){
          User.subscribe(req.socket,listOfUsers);
        console.log('User with socket id '+req.socket.id+' is now subscribed to all of the model instances in \'users\'.');
        });

        } else {

          res.view();

        }
    }
}

    // Don't forget to handle your errors

views/users/testSocket.ejs

<script type="text/javascript">
window.onload = function subscribeAndListen(){
    // When the document loads, send a request to users.testSocket
    // The controller code will subscribe you to all of the 'users' model instances (records)
    socket.get('/users/testSocket/');

    // Listen for the event called 'user'
    socket.on('user',function(obj){
      if (obj.verb == 'updated') {
        var previous = obj.previous;
        var data = obj.data;
        console.log('User '+previous.name+' has been updated to '+data.name);
      }
    });
};

function doEdit(){

    // Send the name to the testSocket action on the 'Users' contoller

    socket.get('/users/testSocket/',{name:'Walter'});
}

</script>
<div class="addButton" onClick="doEdit()">Click Me to add a new User! </div>

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