Anton Kallenberg
May 24, 2012
  2410
(0 votes)

Page Constraints

I have built a small plug-in that I call PageConstraints. The plugin adds support for adding constraints to PageTypeBuilder page types. Constraints can be added with .NETs built-in DataAnnotations or by implementing custom code.

For example. Following page type is a regular PTB page type with built-in DataAnnotation attributes and a custom Attribute (UrlResolvable).

   1: [PageType("73312396-6092-475f-9f3a-e5be1adfcf95", Filename = "~/Templates/Pages/Author.aspx")]
   2: public class AuthorPage : TypedPageData
   3: {
   4:     [Required(ErrorMessage = "name cant be empty")]
   5:     [PageTypeProperty(Type = typeof(PropertyString))]
   6:     public virtual string Name { get; set; }
   7:  
   8:     [UrlResolvable(@"^http\://[a-zA-Z0-9\-\.]+\.[a-zA-Z]{2,3}(/\S*)?$", ErrorMessage = "could not resolve remote url or remote server did not return status code 200")]
   9:     [PageTypeProperty(Type = typeof(PropertyString))]
  10:     public virtual string WebPage { get; set; }
  11:  
  12:     [Range(18, 130, ErrorMessage = "author must be between 18 and 130 years old")]
  13:     public virtual int? Age { get; set; }
  14: }

 

Custom attributes

Its quite simple to implement a custom DataAnnotation attribute that you can add to your page type. Following Attribute is checking if a entered url is a valid uri, matching a regular expression and if the remote server of the entered url is returning a response with http status 200 by extending build-in RegularExpressionAttribute. You can see how it can be used with WebPage property at AuthorPage.

   1: public class UrlResolvableAttribute : RegularExpressionAttribute
   2: {
   3:     public string Url { get; set; }
   4:  
   5:     public UrlResolvableAttribute(string pattern) : base(pattern) { }
   6:  
   7:     public override bool IsValid(object value)
   8:     {
   9:         if (value == null) return true;
  10:  
  11:         var valid = base.IsValid(value);
  12:         if (!valid)
  13:             return false;
  14:  
  15:         string url;
  16:         if (!GetUrl(value, out url)) return false;
  17:  
  18:         Uri uri;
  19:         if (!GetUri(url, out uri)) return false;
  20:  
  21:         var request = WebRequest.Create(uri.ToString());
  22:         try
  23:         {
  24:             using (var reponse = (HttpWebResponse)request.GetResponse())
  25:             {
  26:                 if (reponse == null)
  27:                 {
  28:                     return false;
  29:                 }
  30:  
  31:                 var statusCode = reponse.StatusCode;
  32:                 return statusCode == HttpStatusCode.OK;
  33:             }
  34:         }
  35:         catch (WebException ex)
  36:         {
  37:             if (ex.Status == WebExceptionStatus.ProtocolError)
  38:             {
  39:                 var response = ex.Response as HttpWebResponse;
  40:                 if (response != null && response.StatusCode != HttpStatusCode.OK)
  41:                 {
  42:                     return false;
  43:                 }
  44:             }
  45:         }
  46:  
  47:         return false;
  48:     }
  49:  
  50:     private bool GetUrl(object value, out string url)
  51:     {
  52:         url = value != null ? value.ToString() : string.Empty;
  53:         if (string.IsNullOrEmpty(url))
  54:         {
  55:             return false;
  56:         }
  57:         return true;
  58:     }
  59:  
  60:     private bool GetUri(string url, out Uri uri)
  61:     {
  62:         uri = null;
  63:         try
  64:         {
  65:             uri = new Uri(url);
  66:         }
  67:         catch (Exception)
  68:         {
  69:             return false;
  70:         }
  71:         return true;
  72:     }
  73: }

Custom constraint

If you need to add custom code that is not supported by DataAnnotations for the constraint with a context of the current page, implement the method IsViolated from interface IConstraintPage.

   1: [PageType("cfe42b48-496c-475e-86db-c2030175bc83", Filename = "~/Templates/Pages/Book.aspx")]
   2: public class BookPage : TypedPageData, IConstraintPage
   3: {
   4:     [Required(ErrorMessage = "book must have a name")]
   5:     [StringLength(30, ErrorMessage = "book cant have a name longer that 10 chars")]
   6:     [PageTypeProperty(Type = typeof(PropertyString))]
   7:     public virtual string Name { get; set; }
   8:  
   9:     [Required(ErrorMessage = "isbn cant be empty")]
  10:     [RegularExpression(@"^(?=[-0-9xX ]{13}$)(?:[0-9]+[- ]){3}[0-9]*[xX0-9]$", ErrorMessage = "isbn is not valid")]
  11:     [PageTypeProperty(Type = typeof(PropertyString))]
  12:     public virtual string Isbn { get; set; }
  13:  
  14:     [Required(ErrorMessage = "book must have authors")]
  15:     [PageTypeProperty(Type = typeof(PropertyLinkCollection))]
  16:     public virtual LinkItemCollection Authors { get; set; }
  17:  
  18:     public bool IsViolated(out string reason)
  19:     {
  20:         reason = string.Empty;
  21:         if (!string.IsNullOrEmpty(Name) && Name.Contains("twilight"))
  22:         {
  23:             reason = "this bookstore does not allow the twilight books";
  24:             return true;
  25:         }
  26:         return false;
  27:     }
  28: }

Error messages are displayed in the standard yellow popup when trying to save or publish the page in edit mode and a EPiServerCancelException is thrown.

Source, tests, examples and compiled binary is available at github. Please let me know if you think this is a needed plugin and if you have ideas for improvements.

Source is compiled with EPiServer CMS R2 (6.1.379.0) and PageTypeBuilder 2.0.

May 24, 2012

Comments

Please login to comment.
Latest blogs
Implementing EmbeddedLocalization in Optimizely CMS 12

My previous post on translation (Translating Optimizely CMS 12 UI components) gives an overview of how to implement the FileXmlLocalizationProvider...

Eric Herlitz | Jan 27, 2023 | Syndicated blog

Breaking changes in EPiServer.CMS.TinyMce 4.0.0

After upgrading to the latest version of EPiServer.CMS.TinyMce, the dropdown with formats disappears. Learn how to get it back!

Tomas Hensrud Gulla | Jan 27, 2023 | Syndicated blog

Translating Optimizely CMS 12 UI components

Optimizely CMS 12 have been out for a while now, but still some elements haven't been properly translated resulting in a GUI defaulting to english....

Eric Herlitz | Jan 26, 2023 | Syndicated blog

Image preview in Optimizely CMS12 all properties view

With these simple steps, you can now see an Image and its Metadata, including size and dimensions, when editing an Image property in Optimizely...

Tomas Hensrud Gulla | Jan 26, 2023 | Syndicated blog