Add a folder with jstree

Question

I read on SO and other pages that I should avoid JavascriptResult, I do not realy know why, but now I use JsonResult, because it is more common.

Here is my Ajax in the cshtml:

                        $.ajax({
                            type: "POST",
                            url: "@Url.Action("AddFolder")",
                            data: {
                                id: currentFolderObject.id,
                                folderId: _childFolderId,
                                newFolderName: data.text,
                                parent: _parentsChildId
                            },
                            success: function (serverData) {
                                if (!serverData.message === undefined) {
                                    if (!serverData.success) {
                                        alert(serverData.message);
                                    }
                                }
                                else {
                                    SetFolderModel(serverData.id, serverData.folderId, serverData.newFolderName, false, serverData.parent, "");

                                    if (!serverData.parent.match("_")) {
                                        FolderProperties(node, serverData.node);
                                    }
                                    else {
                                        $('#foldertree').jstree(true).refresh();
                                    }
                                }
                            },
                        })

So with that Ajax I am calling my AddFolder in my Controller. I think I am doing it rly complicated. On client side I have to use jstree which has a specific structure ( https://www.jstree.com/docs/json/ ). And that is why I am posting here.

    [HttpPost]
    public JsonResult AddFolder(int id, string folderId, string newFolderName, string parent)
    {
        bool publish;
        int mrNumber = 0;
        int parentFolder = Convert.ToInt32(GetFolderId(id).Split('_')[0]);
        int lastPeriod = GetLastPeriod();
        string mrDate = Helper.ConvertToIsoDate(DateTime.Now.ToString().Split(' ')[0]);

        if (lastPeriod == -1)
            throw new Exception(ErrorMessages.PeriodNotFound);

        if (parent == "#")
        {
            publish = true;
            try
            {
                folderId = (_ministerratRepository.GetLastMainFolderId() + 1).ToString();
            }
            catch (Exception ex)
            {
                Logging.LogToFile(ex, (int?)Helper.LogLevel.Error);
                return Json(new { success = false, message = ErrorMessages.CountFolderNotPossible }, JsonRequestBehavior.AllowGet);
            }
        }
        else
        {
            publish = false;
            if (parent.Contains("_"))
                mrNumber = GetLastMrNumber(lastPeriod, folderId);
            else
                mrNumber = GetLastMrNumber(lastPeriod, folderId) + 1;

            int folderIdIndex = 0;
            if (folderId.Count(x => x == '_') == 1)
            {
                folderIdIndex = GetLastFolderIdOfMinisterrat(folderId, parentFolder);

                if (Convert.ToInt32(folderId.Split('_')[1]) <= folderIdIndex)
                    folderId = parentFolder + "_" + Convert.ToInt32(folderIdIndex + 1);
            }
            else
            {
                folderIdIndex = GetLastFolderIdOfMinisterrat(folderId, parentFolder);
                if (Convert.ToInt32(folderId.Split('_')[2]) <= folderIdIndex)
                    folderId = parent + "_" + Convert.ToInt32(folderIdIndex + 1);
            }
        }

        if (mrNumber < 0)
            throw new Exception(ErrorMessages.MrNumberNotFound);

        try
        {
            id = _ministerratRepository.AddFolder(folderId, parent, lastPeriod, mrNumber, newFolderName, publish, mrDate);

            if (id == -1)
                throw new Exception(ErrorMessages.NoIdFound);
        }
        catch (NpgsqlException ex)
        {
            NpgsqlError(ex);
        }
        catch (Exception ex)
        {
            Logging.LogToFile(ex, (int?)Helper.LogLevel.Error);
            return Json(new { success = false, message = ErrorMessages.AddFolderNotPossible }, JsonRequestBehavior.AllowGet);
        }

        return Json(new { id, folderId, newFolderName, parent });
    }

Inside this AddFolder there are some other methods, they are basically returning integers from a DB query. I need folderId and parent to add the folder to the right layer. root (parent) is for example 26, child is 26_1, subchild is 26_1_1. I check that with the underscore.

For me it is looking very long to achieve the main goal to add a folder and I am not sure if i can achiev this easier because in my opinion this method is realy long in comparison to just Add a folder.

Furthermore I would like to know if my naming is correct (parameters, classes, methods) I am using here.