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Validating page data with Data Annotations

Jarle posted a very inspiring post about validating your PageData object upon save. This is a quick post that uses the same technique but uses Data Annotations for validation.

If you’re not familiar with data annotations basically it’s a way to validate your entities by decorating properties with various validation attributes that lives in the System.ComponentModel.DataAnnotations namespace.

Let’s say we have this property in our TypedPageData class

   1: [System.ComponentModel.DataAnnotations.Required(ErrorMessage = "/validationerror/mainbodyisempty")]
   2: [System.ComponentModel.DataAnnotations.StringLength(15, ErrorMessage = "/validationerror/mainbodyistoolong")]
   3: [PageTypeProperty(SortOrder = 100, UniqueValuePerLanguage = true, Searchable = true, Type = typeof(PropertyLongString), Tab = typeof(Tabs.Information))]
   4: public virtual string MainBody
   5: {
   6:     get;
   7:     set;
   8: }

 

In this case I’ve used a path as the ErrorMessage to be able to use the EpiServer functionality of the language xml files. The following simple class validates a given object by finding all properties marked with a ValidationAttribute.

   1: public class PageDataValidator
   2: {
   3:     public IEnumerable<string> GetErrors(object toValidate)
   4:     {
   5:         return TypeDescriptor
   6:             .GetProperties(toValidate)
   7:             .Cast<PropertyDescriptor>()
   8:             .SelectMany(prop =>
   9:                 prop.Attributes.OfType<ValidationAttribute>(),
  10:                 (prop, attribute) => new { prop, attribute })
  11:                 .Where(@t1 => !@t1.attribute.IsValid(@t1.prop.GetValue(toValidate)))
  12:                 .Select(@t1 => LanguageManager.Instance.Translate(@t1.attribute.ErrorMessage));
  13:     }
  14: }

 

In the GlobalPageValidation we simply initiate our PageDataValidator class and performs some simple logic to set the appropriate error(s).

   1: void GlobalPageValidation_Validators(object sender, PageValidateEventArgs e)
   2: {
   3:     PageDataValidator validator = new PageDataValidator();
   4:     var errors = validator.GetErrors(e.Page);
   5:  
   6:     if (errors.Count() > 0)
   7:     {
   8:         e.IsValid = false;
   9:         foreach(var error in errors)
  10:         {
  11:             e.ErrorMessage += error;    
  12:         }
  13:         
  14:     }
  15: }
May 01, 2010

andreas.plahn
(By andreas.plahn, 5/20/2014 12:00:32 PM)

Nice, works fine thank you! =)

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