The property or field has not been initialized. Error throw in sharepoint online?

Question

I have big problem. I tried a lot of solution for this issue but not worked. I need help. Here is my code. I try to get items from picture library. It's an app for sharepoint online.

var context;
var web;
var user;
var list;
var slider_container = $(".bxslider");


var hostUrl = decodeURIComponent(getQueryStringParameter("SPHostUrl"));

currentcontext = new SP.ClientContext.get_current();
hostcontext = new SP.AppContextSite(currentcontext, hostUrl);
web = hostcontext.get_web();
list = web.get_lists().getByTitle("Slider");


var camlQuery = new SP.CamlQuery();
camlQuery.set_viewXml('<Query><OrderBy><FieldRef Name=\'ID\'/></OrderBy></Query>');
var collListItem = list.getItems(camlQuery);




currentcontext.load(list);
currentcontext.load(collListItem, 'Include(ID, FileRef)');
currentcontext.executeQueryAsync(onList, onFailList);


function getQueryStringParameter(paramToRetrieve) {
    var params =
    document.URL.split("?")[1].split("&");
    var strParams = "";
    for (var i = 0; i < params.length; i = i + 1) {
        var singleParam = params[i].split("=");
        if (singleParam[0] == paramToRetrieve)
            return singleParam[1];
    }
}


function onList() {

    var numerator = collListItem.getEnumerator();

    while (numerator.moveNext()) {

        var oListItem = numerator.get_current();

        var img = oListItem.get_item("FileRef"); //imgurl olacak
        var intname = oListItem.get_internalName();
        console.log(intname);

        var html = '<li><img src="' + img + '" /></li>';

        slider_container.append(html);


    }

}

Answer 1

You need to include <View /> in the Caml:

camlQuery.set_viewXml('<View><Query><OrderBy><FieldRef Name=\'ID\'/></OrderBy></Query></View>');