Get item from external list field with ajax - SP2013

Question

I have a list and some columns retrieve value from external list. How to get all items from that list(attached img) with REST

I'm trying like this

function traerSolicitudes() {
        var lista = "MetadataTabla";
        var siteUrl = _spPageContextInfo.webAbsoluteUrl;
    var hostweburl = _spPageContextInfo.webAbsoluteUrl;
        +_spPageContextInfo.webServerRelativeUrl;

    var scriptbase = hostweburl + "/_layouts/15/";
    $.getScript(scriptbase + "SP.RequestExecutor.js", ejecutarCrossDomain);
    function ejecutarCrossDomain() {
            var executor = new SP.RequestExecutor(siteUrl);
            var urlRest = siteUrl + "/_api/web/lists/GetByTitle('"
                + lista + "')/items?";
            myList = [];
            traerTodosLosItems();
            function traerTodosLosItems() {
        executor.executeAsync({
                    url: urlRest,
               type: "GET",
               headers: {
                   "accept": "application/json;odata=verbose",
               },
               success: function (data) {
                var jsonObject = JSON.parse(data.body);

                $.each(jsonObject.d.results, function (index, item) {

                  console.log(jsonObject.d.results)
                   });

                   },
                   error: function (error) {

                       alert(JSON.stringify(error));
                   }
               });
            }
        }
    }

Result:

the REST retrieve just field items like datetime, text and number, but not "external data" type, in the console.log external data fields type return NULL

Answer 1

this is the way I retrieve the external content type items. I define all fields i want to retrieve in the select of the rest api

   $select=metadata_tablaID,informacion,valor,tipo_de_dato," +
           "duenho,fecha_de_carga,fecha_de_vigencia,selloID,capituloID,checklistID,frameworkID,grupoID,maestroClasificadorID,nivelID