Angularjs and relational databases

I have been working on a webapp which will show forum topics. Now my problem is that I can't show user name on every topic reply.

ERD

Now the important part of this is persona(users) is related with respuestas (replys) through id_persona.

I'm trying to get users information like (name, lastname which are in persona database), So I have using some solutions.

HTML

<h2>{{titulo}}</h2>
<p>{{texto}}</p>
<div class="row">
    <div class="container" ng-repeat="respuesta in respuestas">
        <!-- solution 1 -->
        <span>{{ getPersona(respuesta[3]) }}</span>
        <!-- solution 2 -->
        <div ng-init="searchUser(respuesta[3])">
            <span ng-repeat="user in users" ng-if="respuesta[3] == user[0]">{{user[0]}}</span>
        </div>
        <p>{{respuesta[1]}}</p>
    </div>
</div>

Titulo and texto are part of my tema (topic) which I got with $routeParams.

ng-repeat is getting every reply which is associated with this topic

now, solution 1 is <span>{{ getPersona(respuesta[3]) }}</span> where in my controller I have a function that get respuesta[3] (which is id_persona).

$scope.getPersona = function(persona) {

        var url3 =  'http:/WEBSERVICE/persona?filter=id,eq,' + persona;

         $http.get(url3).then( function(response) {
            //console.log(response);
            var user = response.data.persona.records[0];
            console.log(user)
            return user;
         });
    }

This should return an array with user information, but I'm getting an error

10 $digest() iterations reached. Aborting!
Watchers fired in the last 5 iterations: []

net::ERR_INSUFFICIENT_RESOURCES

Second solution was <div ng-init="searchUser(respuesta[3])"> which also send respuesta[3] to function searchUser. this solution is creating an array(users) which has the information of users who reply on the topic and then with nf-if filter the one where respuesta[3] = user.id.

$scope.users = []
    $scope.searchUser =  function(persona) {
        
        var url3 =  'https://WEBSERVICE/persona?filter=id,eq,' + persona;

         $http.get(url3).then( function(response) {
        var user = {
            id: response.data.persona.records[0][0],
            nombres: response.data.persona.records[0][3],
            apellidos: response.data.persona.records[0][4] + ' ' + response.data.persona.records[0][5]
        };
        //console.log(user)
        if ($scope.users.indexOf(user) == -1) {             
            $scope.users.push(user);
            console.log($scope.users.indexOf(user));
            console.log($scope.users)
        }       
     })
}

What is the problem with this?

I don't my users get duplicate in the array Users that why I'm using $scope.users.indexOf(user)

I think solution 1 should be the one which work faster but it doesn't work and solution 2 works, but I'm getting duplicate user, also a try to do a for, but I didn't understand how it works, I did this:

for (var i = 0; i < $scope.users.length; i++) {
                if($scope.users[i].id === users.id) {
                    console.log('ya existe');
                } else {
                    $scope.users.push(user);
                }
                console.log($scope.users)
            }