angular: how to use $scope with variable?

Question

I'm beginner in angular. I'm using $http to get JSON data from the server by clicking on a button. my end goal is to fill all my HTML input forms with the server returning data automatically. I'm trying to do this with a forEach loop:

$http.post("check_ad", postData, config).then(function (response) {
    angular.forEach(response.data.getValue, function(value, key) {
        $scope.key = value;
    });
});

My HTML is:

<input type="text" ng-model="test">
<input type="text" ng-model="test2">

The server returning data is:

{"getValue":{"test":"hello","test2":"world"}}

My problem is that "key" variable is not working for me. If I'm trying to go direct without the "key" it's working OK:

$http.post("check_ad", postData, config).then(function (response) {
    angular.forEach(response.data.getValue, function(value, key) {
        $scope.test = value;
        $scope.test2 = value;
    });
});

My question is how i'm using $scope with variable? And another question is if there is a better way to do that Instead using forEach?

Thanks you :)