app.directive('testSort', () => ({
    scope: true,
    link: (scope) => {
        scope.items = [
            {ranking: {nature: 1, computers: 2}},
            {ranking: {nature: 2, computers: 1}},
            {ranking: {nature: 3}},
        ]
    }
}))

/*
<test-sort>
    <div ng-repeat="item in items | orderBy:'-ranking.nature'">
        <pre>{{item | json}}</pre>
    </div>
</test-sort>
*/