How do you do web forms model validation?

问题:

We have an application with three layers: UI, Business, and Data. The data layer houses Entity Framework v4 and auto-generates our entity objects. I have created a buddy class for the entity VendorInfo:

namespace Company.DataAccess {     [MetadataType(typeof(VendorInfoMetadata))]     public partial class VendorInfo     {     }      public class VendorInfoMetadata     {         [Required]         public string Title;          [Required]         public string Link;          [Required]         public string LinkText;          [Required]         public string Description;     } } 

I want this validation to bubble up to the UI, including custom validation messages assigned to them. In MVC this is a piece of cake but in web forms I have no clue where to begin. What is the best way to utilize model validation in asp.net web forms?

I did find an article that explains how to build a server control for it, but I can't seem to get it working. It compiles and even recognizes the control but I can never get it to fire.

Any ideas?

Thanks everyone.

回答1:

I solved it. It would appear that the server control I found was not designed to read fields in a buddy class via the MetadataType attribute. I modified the code to look for its validation attributes in the buddy class rather than the entity class itself.

Here is the modified version of the linked server control:

    [DefaultProperty("Text")]     [ToolboxData("<{0}:DataAnnotationValidator runat=server></{0}:DataAnnotationValidator>")]     public class DataAnnotationValidator : BaseValidator     {         #region Properties          /// <summary>         /// The type of the source to check         /// </summary>         public string SourceTypeName { get; set; }          /// <summary>         /// The property that is annotated         /// </summary>         public string PropertyName { get; set; }          #endregion          #region Methods          protected override bool EvaluateIsValid()         {             // get the type that we are going to validate             Type source = GetValidatedType();              // get the property to validate             FieldInfo property = GetValidatedProperty(source);              // get the control validation value             string value = GetControlValidationValue(ControlToValidate);              foreach (var attribute in property.GetCustomAttributes(                      typeof(ValidationAttribute), true)                        .OfType<ValidationAttribute>())             {                 if (!attribute.IsValid(value))                 {                     ErrorMessage = attribute.ErrorMessage;                     return false;                 }             }             return true;         }          private Type GetValidatedType()         {             if (string.IsNullOrEmpty(SourceTypeName))             {                 throw new InvalidOperationException(                   "Null SourceTypeName can't be validated");             }              Type validatedType = Type.GetType(SourceTypeName);             if (validatedType == null)             {                 throw new InvalidOperationException(                     string.Format("{0}:{1}",                       "Invalid SourceTypeName", SourceTypeName));             }              IEnumerable<MetadataTypeAttribute> mt = validatedType.GetCustomAttributes(typeof(MetadataTypeAttribute), false).OfType<MetadataTypeAttribute>();             if (mt.Count() > 0)             {                 validatedType = mt.First().MetadataClassType;             }              return validatedType;         }          private FieldInfo GetValidatedProperty(Type source)         {             FieldInfo field = source.GetField(PropertyName);             if (field == null)             {                 throw new InvalidOperationException(                   string.Format("{0}:{1}",                     "Validated Property Does Not Exists", PropertyName));             }             return field;         }          #endregion     } 

This code only looks in the buddy class. If you want it to check an actual class and then its buddy class, you'll have to modify it accordingly. I did not bother doing that because usually if you are using a buddy class for validation attributes it's because you are not able to use the attributes in the main entity class (e.g. Entity Framework).

回答2:

For model validation in web forms I'm using DAValidation library. It supports validation on client side (including unobtrusive validation), extensibility based on same principles as in MVC. It is MS-PL licensed and available via Nuget.

And here is bit out of date article describing with what thoughts control was build.

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