text: Q:
  
  Can not instantiate value of type from JSON String; no single-String constructor/factory method
  
  I have following entities:
  @Entity
  @Table(name="APLICACAO")
  public class Aplicacao implements Serializable, Entidade {
  
      private static final long serialVersionUID = 1L;
  
      @Id
      @GeneratedValue(strategy = GenerationType.IDENTITY)
      @Column(name="CD_APLICACAO")
      private Long codigo;
  
      @Column(name="NM_APLICACAO")
      @NotNull
      private String nome;
  
      @ManyToOne
      @JoinColumn(name="CD_GRUPO")
      private GrupoAplicacao grupoAplicacao;
  
      ....
  
  }
  
  And also:
  @Entity
  @Table(name = "GRUPO_APLICACAO")
  public class GrupoAplicacao implements Serializable, Entidade {
  
      private static final long serialVersionUID = 1L;
  
      @Id
      @GeneratedValue(strategy = GenerationType.IDENTITY)
      @Column(name = "CD_GRUPO")
      private Long codigo;
  
      @Column(name = "NM_GRUPO")
      @NotNull
      private String nome;
  
      @OneToMany(mappedBy = "grupoAplicacao",fetch=FetchType.EAGER)
      private List<Aplicacao> listaAplicacao;
  
      @OneToMany(mappedBy = "grupoAplicacao",fetch=FetchType.EAGER)
      private List<GrupoAplicacaoUsuario> listaGrupoAplicacaoUsuario;
  
      ....
  
  }
  
  My HTML call controller "aplicacoesCreateController", like code bellow:
  <div class="col-xs-12" ng-controller="aplicacoesCreateController">
      <form class="form-horizontal form-medium center" role="form" name="form" ng-submit="save()">
          <div class="form-group">
              <label for="nome" class="col-xs-4 control-label">Nome</label>
              <div class="col-xs-8">
                  <input type="text" class="form-control input-sm" id="nome" placeholder="Nome" required ng-model="aplicacao.nome">
              </div>
          </div>
          <div class="form-group">
              <label for="nome" class="col-xs-4 control-label">Nome</label>
              <div class="col-xs-8">
                  <select class="form-control" required ng-model="aplicacao.grupoAplicacao">
                          <option ng-repeat="grupo in grupos" value="{{ grupo }}">
                              {{ grupo.nome }}
                          </option>
                  </select>
              </div>
          </div>
          <div class="form-group">
              <div class="col-xs-offset-4 col-xs-8">
              <button type="submit" class="btn btn-lg btn-size-md">Salvar</button>
              </div>
          </div>
      </form>
  </div>
  
  And my Controller JavaScript:
  app.controller('aplicacoesCreateController', ['$scope','aplicacoesService','$location','reloadService','gruposService',
  function ($scope,aplicacoesService,$location,reloadService,gruposService) {
      $scope.grupos = gruposService.list();
      $scope.save = function () {
          aplicacoesService.create($scope.aplicacao);
          reloadService.on('#/aplicacoes');
      };
  }]);
  
  And Services JavaScript:
  app.factory('gruposService', ['$resource', function ($resource) {
  
      return $resource('resources/grupo-aplicacao', {}, {
          'list': { method: 'GET', isArray: true }
      });
  
  }]);
  
  And other service:
  app.factory('aplicacoesService', ['$resource', function ($resource) {
  
      return $resource('resources/aplicacao', {}, {
          'list': { method: 'GET', isArray: true },
          'create': { method: 'POST' }
      });
  
  }]);
  
  When insert aplicacao entity, is show me the following error:
  Caused by: org.codehaus.jackson.map.JsonMappingException: Can not instantiate value of type [simple type, class br.com.techpeople.grape.entity.GrupoAplicacao] from JSON String; no single-String constructor/factory method (through reference chain: br.com.techpeople.grape.entity.Aplicacao["grupoAplicacao"])
  
  Could you help me with this error?
  
  A:
  
  The error is telling you that you need a constructor method in your GrupoAplicacao class which accepts a string.
  @Entity
  @Table(name = "GRUPO_APLICACAO")
  public class GrupoAplicacao implements Serializable, Entidade {
  
  ....
  
      GrupoAplicacao(String stringJSON){
          setters;
      }
  
  }
  
  