Function automatically called in some condition - angularjs

Question

I have code like this：
<div class="row"
ng-repeat="x in companies|orderBy:'id' ">
<div class="col left" >
<button ng-click="viewPublicId(x.id)">{{x.companyname}}</button>
</div>
<div class="col left">
{{x.address}}
</div>
<div class="col left">
{{x.telephone}}
</div>
</div>
What I want to do is add a check: when companies.size=1, function viewPublicId is automatically called. How can I achieve that? Thanks.
updated: viewPublicId function:
$scope.viewPublicId = function viewPublicId(companyid) {
var url = "http://7cf8d64c.tunnel.mobi/yii2-basic/web/index.php?r=restpublic/view&companyid=" + companyid;
console.log("debug", url);
$http.get(url)
.success(function (response)
{
console.log("debug PublicId",response);
if(response.length==33)
$scope.publicids = null;
else
$scope.publicids = response;
})
.error(function (response)
{
console.log("debug PublicId",response);
$scope.publicids = null;
});
$state.go('tabs.publicidlist');
}

Answer 1

In you controller:
if ($scope.companies.length === 1) {
$scope.viewPublicId();
}
If your companies could be changed dynamically, and you need to call the function everytime it changes, use $watch:
$scope.$watch('companies', function () {
if ($scope.companies.length === 1) {
$scope.viewPublicId();
}
}, true);