Tagged by 'placeholder'

  • Regardless of any site you have worked on, there is always a potential problem of a page rendering broken images. This is more likely to happen when images are served from external sources or through accidental deletion within content management platforms.

    The only way I found a way to deal with this issue, is to provide a fallback alternative if the image to be served cannot be found. I've created a FallbackImage() extension method that can be applied to any string variable that contains a path to an image.

    public static class ImageExtensions
        /// <summary>
        /// Creates a fallback image if the image requested does not exist.
        /// </summary>
        /// <param name="imageUrl"></param>
        /// <returns></returns>
        public static string FallbackImage(this string imageUrl)
            string cachedImagePath = CacheEngine.Get<string>(imageUrl);
            if (string.IsNullOrEmpty(cachedImagePath))
                string sanitiseImageUrl = string.Empty;
                if (!imageUrl.IsExternalLink())
                    sanitiseImageUrl = $"{HttpContext.Current.GetCurrentDomain()}{imageUrl.Replace("~", string.Empty)}";
                // Attempt to request the image.
                WebRequest request = WebRequest.Create(sanitiseImageUrl);
                    WebResponse response = request.GetResponse();
                    cachedImagePath = imageUrl;
                catch (Exception ex)
                    cachedImagePath = "/resources/images/placeholder.jpg";
                // Add image path to cache.
                CacheEngine.Add(cachedImagePath, imageUrl, 5);
            return cachedImagePath;

    To ensure optimum performance to minimise any unnecessary checks for the same image, the request is stored in cache for 5 minutes.

    The method is using some functionality that I have developed within my own website, which will only work when referenced in your own codebase:

    • GetCurrentDomain - get the full URL of the current domain including any protocols and ports.
    • CacheEngine - provides a bunch of helper methods to interact with .NET cache provider easily.
  • I've been a .NET Developer for around 6 years and it still amazes me how I can overlook something that I never really questioned. For example, when a user control is hidden, I always assumed that all the code it contained would never run since until it was made visible.

    However, after being told by one of my work colleagues that in fact a hidden user control will always run, it will just simply is hidden by the client. After searching the web for a definitive answer, I found a StackOverflow post that fully backed up his theory:

    As the StackOverflow post suggests, the most performance efficient way to show/hide a user control is by dynamically loading it in when required.

    if (jobs.Count > 0)

    As you can see in my example above, I'm loading my user control to a place holder in the page.