angular of

I generated a multi-level select through json

<code><div ng-app="xx" ng-controller="eee">
   <div>
                   

 **{{col_selectlv[1].colname}}**//这个地方下文说到！

                    <select ng-model="col_selectlv[0]" ng-options="x.colname for x in col_select[0]" required>

                        <option></option>
                    </select>
                    <select ng-model="col_selectlv[1]" ng-options="x.colname for x in col_selectlv[0].children"
                            ng-if="col_selectlv[0].children"
                            required >
                        <option></option>
                    </select>
                    <select ng-model="col_selectlv[2]" ng-options="x.colname for x in col_selectlv[1].children"
                            ng-if="col_selectlv[1].children" required >
                        <option></option>
                    </select>
                    <select ng-model="col_selectlv[3]" ng-options="x.colname for x in col_selectlv[2].children"
                            ng-if="col_selectlv[2].children" required >
                        <option></option>
                    </select>
                   
                </div>
</div></code>

app.js looks like this:

<code> app.controller('newseditor', function ($scope, $http,$routeParams) {
           $scope.newsid=$routeParams.id?$routeParams.id:'0';
            $http({
                method: 'GET',
                url: 'datacon/col_select.php',

            }).success(function (response) {
                //    console.log(response);
                if (response)
                    $scope.col_select = response;

            })
            $scope.change_selecter = function (r) {
                $scope.select_range = r;
            }
            $scope.news_submit = function () {
                console.log($scope.col_selectlv)

            }
           


        });</code>

Activate news_submit by clicking the button. The desired effect is to output col_selectlv, but the output result is undefined.
ng-model is bound successfully, because the {{col_selectlv[1].colname}} marked above can be output, but I don’t know why it cannot be obtained through $scope.col_selectlv.