filter $scope Error: Unknown provider: $scopeProvider <- $scope <- transformSensorStatusFilter

Question

marsApp.filter("transformSensorStatus", function($scope) {
    return function(input, options) {

    var sensorReading = ( input ? ( input / 1000) : 0);
    var sensorLowLimit = (options["lowLimit"] ? (options["lowLimit"] / 1000) : 0);
    var sensorHighLimit = (options["highLimit"] ? (options["highLimit"] / 1000) : 0);
    var curStat;
    switch (sensorReading) {
        case 255:
        case 254:
        case 253:
            curStat = generateStateInnerHtml(sensorReading);
            break;
        default:
            curStat = generateStateInnerHtml(options["sensorStatus"]);

    }

    return curStat;


    function generateStateInnerHtml(state) {

        var stateHtml = null;

        if (state == 255 || state == 254) {
            stateHtml = "a";
            $scope.sensorStateColor='';
            return state_html;
        }
        if (state == 253) {
            stateHtml = "b";
            $scope.sensorStateColor="text-warning";
            return state_html;
        }
        if (state >= 0x20) {
            stateHtml = "c";
            $scope.sensorStateColor="text-error";
            return stateHtml;
        }
        if (state >= 0x02) {
            stateHtml = "d";
            $scope.sensorStateColor="text-error";
            return stateHtml;
        }
        if (state == 0x01) {
            stateHtml = "e";
            $scope.sensorStateColor="text-success";
            return stateHtml;
        }
        stateHtml = "N/A";
        return stateHtml;
    }
}

});

in chrome , I get the following error:

Error: Unknown provider: $scopeProvider <- $scope <- transformSensorStatusFilter

Answer 1

The $scope is available only for controllers and the link function of directives. This is why the filter cannot find it. Maybe you meant $rootScope?

Answer 2

I found that "this" references local $scope (inside filter function.) Not sure if this is safe way of accessing it tho.