Check if a record came back-end null in Angular

Question

I have a modal where I have two text inputs: CPF and Senha. In the input of CPF have a ng-blur who makes a Requisition GET every time I change fields. If I type a CPF that exists in the bank he made the GET correctly, but would like to display some warning if you do not find the CPF in the back-end.

When I try to fetch a CPF that does not exist this is the error that happens on the server:

GRAVE: Servlet.service() for Servlet [default] in context with path [/Unimedws] threw Exception [java.lang.Nullpointerexception: You can’t serialize null Objects] with root cause java.lang.Nullpointerexception: You can’t serialize null Objects

How can I treat this error in the best way possible and put an alert on a message or even a red outline on input of CPF?

Function that makes the GET and is passed to the ng-blur:

  $scope.getBeneficiario = function(usuario){
    loginAPI.getBeneficiario(usuario.cpf).success(function(data){
        console.log("uhul" +data);
        return loginAPI.getBeneficiario(usuario.cpf);

    })
    .error(function(response, status) {
        console.log("Resposta: "+response +"Status: "+status);

    });     
};

PAGE ERROR:

Page:

<div class="alinhar">
   <form name="usuarioForm">
      <input class="form-control" type="text" name="nome" placeholder="CPF" ng-model="usuario.cpf" ng-required="true" ng-blur="getBeneficiario(usuario)" />
      <input class="form-control" type="text" name="fone" placeholder="Senha" ng-model="usuario.senha" 
         ng-required="true"/>
   </form>
</div>
<div class="modal-footer">
   <button class="btn btn-primary btn-block" ng-click="adicionarUsuario(usuario)" ng-disabled="usuarioForm.$invalid">Salvar</button>
</div>

Answer 1

Just you check the return of loginAPI.getBeneficiario(usuario.cpf);.

try to do it this way:

  $scope.getBeneficiario = function(usuario){
    loginAPI.getBeneficiario(usuario.cpf).success(function(data){
        console.log("uhul" +data);
        var res = loginAPI.getBeneficiario(usuario.cpf);
        if (res != null)
          return res;
        else return "";

    })
    .error(function(response, status) {
        console.log("Resposta: "+response +"Status: "+status);

    });     
};

Answer 2

First, you need to check how you are treating the "Find No Record" factor on the server side.

I would use 2 ways from the server side.

1st found record, return a Request with Status 200 (Ok), found no record, returns a Request with status 412 (Pre-condition failed).

on the Client side.

(Como não sei o que seu getBeneficiario faz).

    $http('url get benefeficiar  + cpf').then(function(retorno) { 

    if(retorno.status === 200) { // successo
       //aqui não será null

    }else{
        //aqui o retorno é o null, por que você está tratando do lado do server.
    }
} );

2nd case not to handle server side.

    $http('url get benefeficiar  + cpf').then(function(retorno) { 

       if(retorno.data !== null || retorno.data !== undefined){
          //Código aqui,
       }
    });