oqtane.framework/Oqtane.Client/Services/ServiceBase.cs

using System;
using Oqtane.Models;

namespace Oqtane.Services
{
    public class ServiceBase
    {

        public static string CreateApiUrl(Alias alias, string absoluteUri, string serviceName)
        {
            Uri uri = new Uri(absoluteUri);

            string apiurl;
            if (alias != null)
            {
                // build a url which passes the alias that may include a subfolder for multi-tenancy
                apiurl = $"{uri.Scheme}://{alias.Name}/";
                if (alias.Path == string.Empty)
                {
                    apiurl += "~/";
                }
            }
            else
            {
                // build a url which ignores any subfolder for multi-tenancy
                apiurl = $"{uri.Scheme}://{uri.Authority}/~/";
            }
            apiurl += $"api/{serviceName}";
            
            return apiurl;
        }

        public static string CreateCrossTenantUrl(string url, Alias alias)
        {
            if (alias != null)
            {
                url += (url.Contains("?")) ? "&" : "?";
                url += "aliasid=" + alias.AliasId.ToString();
            }
            return url;
        }
    }
}