Revamp your AngularJS controller for a fresh new look

Question

Revamp your AngularJS controller for a fresh new look

How can a controller be refreshed in Angular? Take into account the scenario below:

<div ng-controller="MsgCtrl" ng-repeat="m in messages">{{m}}<br></div>
<script>
var ws = new WebSocket(something, something);
function MsgCtrl($scope) {
    $scope.messages = [];
    ws.onmessage = function(e) {
        $scope.$apply(function() {
            $scope.messages.push(e.data);
        });
    }
}
</script>

If the websocket connection fails, or needs to be restarted for any reason, a new websocket must be created and listened to. Is there a way to trigger the controller to run again, creating a new listener to push messages from the new connection into $scope?

In addition, as a follow-up question: Where is a reliable source to expand knowledge on Angular? The documentation on the official site may not provide clear guidance.

javascript angularjs

Answer 1

Answer №1

When there is a connection failure or the need to restart for any reason, it is important to reconnect the web socket. However, simply restarting the controller may not be the best approach.

Instead, I recommend creating a dedicated "web socket" service that can handle its own logic, such as reconnecting when needed. This way, the controller can focus on managing the model and view binding without getting bogged down with socket handling.

<html ng-app="MyApp">
....
<div ng-controller="MsgCtrl" ng-repeat="m in messages">{{m}}<br></div>
</html>
<script>

    var myApp = angular.module("MyApp",[]);
    myApp.factory("WebSocket",function(){
        var ws;
        var triedTime=0;
        var maxRetryTime=20;
        return {
            createWS: function(server,protocol,handler){
                ws = new WebSocket(server, protocol);
                ws.onmessage = handler;
                ws.onerror = function(e){
                    this.restartWS(server,protocol,handler);
                }
            },
            closeWS: function(){
                if(ws) ws.close();
            },
            restartWS: function(server,protocol,handler){
                if(triedTime<=maxRetryTime){
                    this.closeWS();
                    this.createWS(server,protocol);
                    triedTime++;
                }
            }
        };
    });

    function MsgCtrl($scope, WebSocket){
        $scope.messages = [];

        WebSocket.createWS("something","something",$scope.msgHandler);

        $scope.msgHandler = function(e){
            $scope.$apply(function() {
                //model update
                $scope.messages.push(e.data);

                var msg = JSON.parse(e.data);

                switch(msg.cmd)
                {
                    case "restart":
                    WebSocket.restartWS("something","something",$scope.msgHandler);
                    break;
                }
            });
        }

    }
</script>

In this scenario, the web socket will automatically attempt to reconnect upon receiving a "restart" message or encountering a connection issue. Hopefully, this solution proves useful for your needs.

Answer 2

When there is a connection failure or the need to restart for any reason, it is important to reconnect the web socket. However, simply restarting the controller may not be the best approach.

Instead, I recommend creating a dedicated "web socket" service that can handle its own logic, such as reconnecting when needed. This way, the controller can focus on managing the model and view binding without getting bogged down with socket handling.

<html ng-app="MyApp">
....
<div ng-controller="MsgCtrl" ng-repeat="m in messages">{{m}}<br></div>
</html>
<script>

    var myApp = angular.module("MyApp",[]);
    myApp.factory("WebSocket",function(){
        var ws;
        var triedTime=0;
        var maxRetryTime=20;
        return {
            createWS: function(server,protocol,handler){
                ws = new WebSocket(server, protocol);
                ws.onmessage = handler;
                ws.onerror = function(e){
                    this.restartWS(server,protocol,handler);
                }
            },
            closeWS: function(){
                if(ws) ws.close();
            },
            restartWS: function(server,protocol,handler){
                if(triedTime<=maxRetryTime){
                    this.closeWS();
                    this.createWS(server,protocol);
                    triedTime++;
                }
            }
        };
    });

    function MsgCtrl($scope, WebSocket){
        $scope.messages = [];

        WebSocket.createWS("something","something",$scope.msgHandler);

        $scope.msgHandler = function(e){
            $scope.$apply(function() {
                //model update
                $scope.messages.push(e.data);

                var msg = JSON.parse(e.data);

                switch(msg.cmd)
                {
                    case "restart":
                    WebSocket.restartWS("something","something",$scope.msgHandler);
                    break;
                }
            });
        }

    }
</script>

In this scenario, the web socket will automatically attempt to reconnect upon receiving a "restart" message or encountering a connection issue. Hopefully, this solution proves useful for your needs.

Answer 3

Answer №2

If you encounter issues, a simple solution is attempting to reload the page using $route.reload(). An even better approach is to reinitiate the websocket on the onerror.
In my experience, the most beneficial platform for learning angularJS is Egghead. Additionally, stackoverflow serves as an excellent resource to seek clarification when needed.

Answer 4

If you encounter issues, a simple solution is attempting to reload the page using $route.reload(). An even better approach is to reinitiate the websocket on the onerror.
In my experience, the most beneficial platform for learning angularJS is Egghead. Additionally, stackoverflow serves as an excellent resource to seek clarification when needed.

Revamp your AngularJS controller for a fresh new look

Answer №1

Answer №2

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