Umbraco - Fix Drop Down Pre Value Display In List Views Handler

MyUmbracoApplication.cs

#region

using System;
using System.Linq;
using System.Net.Http;
using System.Threading;
using System.Threading.Tasks;
using System.Web.Http;
using Umbraco.Core;
using Umbraco.Core.Models;
using Umbraco.Web;
using Umbraco.Web.Models.ContentEditing;

#endregion

public class MyUmbracoApplication : UmbracoApplication
{
    protected override void OnApplicationStarted(object sender, EventArgs e)
    {
        base.OnApplicationStarted(sender, e);

        GlobalConfiguration.Configuration.MessageHandlers.Add(new FixDropDownPreValueDisplayInListViewsHandler());
    }
}

public class FixDropDownPreValueDisplayInListViewsHandler : DelegatingHandler
{
    protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        // wait for the request to be processed
        var response = await base.SendAsync(request, cancellationToken);

        // ensure we're only processing requests to getchildren - hopefully only listviews
        if (request?.RequestUri?.AbsolutePath.Equals("/umbraco/backoffice/UmbracoApi/Content/GetChildren") == true)
        {
            // get the response value and cast to type returned by ContentController.GetChildren
            var content = (ObjectContent)response.Content;
            var data = content?.Value as PagedResult<ContentItemBasic<ContentPropertyBasic, IContent>>;

            foreach (var item in data?.Items)
                foreach (var prop in item?.Properties.Where(p => p?.Editor == "Umbraco.DropDown"))
                {
                    // swap the prevalue id to the string using the datatype service
                    var propStr = prop.Value?.ToString();
                    if (!propStr.IsNullOrWhiteSpace())
                        prop.Value = ApplicationContext.Current.Services.DataTypeService.GetPreValueAsString(Convert.ToInt32(prop.Value));
                }
        }

        return response;
    }
}

This still works in Umbraco 7.14 but with a few amendments.

Line 41: foreach (var prop in item?.Properties.Where(p => p?.Editor == "Umbraco.DropDown.Flexible"))

Line 46: prop.Value = ApplicationContext.Current.Services.DataTypeService.GetPreValueAsString(Convert.ToInt32(((string[])prop.Value)?[0]));