SharePoint 2013 RestAPI retrieve Task and subtask Parent id undefined

Question

I am trying to retrieve the sub-task of the parent task from a list. query:

../_api/web/lists/getbytitle('Tasks')/items?$select=Title,Status,ParentID/Id&$expand=ParentID

Code:

function onQuerySucceeded(data) {
    var mainTasks = [];
    var subTasks = [];
    for (var i = 0; i < data.length; i++) {
        if (data[i].ParentID.Id) {
            subTasks.push(data[i]);
        } else {
            mainTasks.push(data[i]);
        }

    }
    $.each(data.d.results, function (key, value) {
        subTasks += '<strong>Title: </strong> ' + value.Title +
            ' <strong>Status:</strong> ' + value.Status + ' <strong>Parent Id:</strong> ' + value.Id +
            '<br />';
    });

    $("#divSubTaskItems").html(subTasks);

};

My results are:

undefined: "Title: Test rest Call Status: In Progress Parent Id: undefined"

Answer 1

Try adding console.log(value); inside your $.each to see what data you have:

$.each(data.d.results, function (key, value) {
    console.log(value);
    subTasks += '<strong>Title: </strong> ' + value.Title +
        ' <strong>Status:</strong> ' + value.Status + ' <strong>Parent Id:</strong> ' + value.Id +
        '<br />';
});

Most likely, value.Id is indeed undefined. This is because you don't request it

Try this REST query instead:

?$select=Title,Status,Predecessors,Predecessors/Id&$expand=Predecessors