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POHow to use Data Annotations on the ViewModel?
 

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  1. POHow to use Data Annotations on the ViewModel?
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    <p>I'm using RIA Services with LinqToEntitiesDomainService&lt;> and Silverlight 5 Beta to generate the DomainContext code on the client side. I have Data Annotations in my Models/Entities to do basic validations, and when using the Models directly, controls such as DataForm perform validations out-of-the-box. But I'm wrapping my Model in a ViewModel, so I lose all of that automatic validation. Here is a simplified example:</p> <pre><code>// In DataModel assembly, regenerated on the client side by RIA Services public class PetModel { [Required] public string Name { get; set; } } // Only on the client side public class PetViewmodel { private PetModel _model; public PetViewmodel(PetModel model) { _model = model; } public string Name { get { return _model.Name; } set { _model.Name = value; } } } </code></pre> <p>My question is: how can I ensure that <code>Name</code> is considered <code>Required</code> on the client side without duplicating all of my annotations in the ViewModel? (I may have to use these Entities with different ViewModels in the future - and I'd like to keep the same annotations)</p> <p>I thought of manually adding the <code>MetadataType</code> attribute to the ViewModel, pointing to the Model type:</p> <pre><code>[MetadataType(typeof(PetModel))] public class PetViewmodel { ... } </code></pre> <p>But alas, <code>MetadataTypeAttribute</code> is not available in the Silverlight 5 version of <code>System.ComponentModel.DataAnnotations</code>.</p> <p>Edit: Clarification - the metadata for my entities is included in the entities with a nested class. I code this class manually because my L2E model is in a separate assembly so the DomainService wizard would not generate it for me. </p> <pre><code>[MetadataType(typeof(Metadata))] public partial class PetModel { [Required] public string Name { get; set; } public class Metadata { [Required] public string Name { get; set; } } } </code></pre> <p>This should be exactly how the wizard would generate the metadata if I understand it correctly. The RIA Services code generator generates the right data annotations in the client code, so it's picking it up correctly.</p>
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    1. CODidn't a .meta.cs file get generated with your domain service?
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    2. CO@subt13: Thanks for the response. I added a clarification that answers your question. You've given me an idea: I think if I separate out my MetaData classes and share them between client and server, I should be able to include them on the client by using partial classes instead of MetadataTypeAttribute. We'll see...
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    3. COGood thanks, I have the same setup as you, but I tried to inherit from DomainService instead.
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