PublishedContentExtensions.cs

public static class PublishedContentExtensions
{
    public static string GetLanguage(this IPublishedContent content, bool recursive = false)
    {
        try
        {
            var db = ApplicationContext.Current.DatabaseContext.Database;
            var sql = "SELECT [languageISOCode] FROM [umbracoLanguage] JOIN [umbracoDomains] ON [umbracoDomains].[domainDefaultLanguage] = [umbracoLanguage].[id] WHERE [umbracoDomains].[domainRootStructureID] = @0";
            var cultureCode = db.ExecuteScalar<string>(sql, content.Id);

            if (!cultureCode.IsNullOrWhiteSpace() || !recursive || content.Parent == null)
                return cultureCode;
        }
        catch (System.ComponentModel.Win32Exception ex)
        {
            LogHelper.Error<IPublishedContent>(string.Format("GetLanguage ({0})", content.DocumentTypeAlias), ex);
        }

        return recursive ? content.Parent.GetLanguage(true) : null;
    }
}