Adding custom property attributes in Entity Framework code

Question

Adding custom property attributes in Entity Framework code

custom-attributes entity-framework

Question

Is there any way to add custom attributes to properties in EF generated code? The only thing I can see as a plausible solution would be to come up with a custom T4 template. However, because of the nature of the attribute it would be impossible to determine the correct attribute parameter per EF property.

AKoran

Popular Answer

You can add this to EDMX file, with Designer also:

<Property Name="Nome" Type="String" Nullable="false" MaxLength="50" Unicode="true" FixedLength="false" >
            <Documentation>
              <Summary>[MyCustomAttribute]</Summary>
            </Documentation>
</Property>

And replace T4:

void WriteProperty(CodeGenerationTools code, EdmProperty edmProperty)
{
    WriteProperty(Accessibility.ForProperty(edmProperty),
                  code.Escape(edmProperty.TypeUsage),
                  code.Escape(edmProperty),
                  code.SpaceAfter(Accessibility.ForGetter(edmProperty)),
                  code.SpaceAfter(Accessibility.ForSetter(edmProperty)));
}

With:

void WriteProperty(CodeGenerationTools code, EdmProperty edmProperty)
{
    if(edmProperty.Documentation != null && string.IsNullOrWhiteSpace(edmProperty.Documentation.Summary) == false)
    {
    #>
    <#=edmProperty.Documentation.Summary#>
<#+
    }
    WriteProperty(Accessibility.ForProperty(edmProperty),
                  code.Escape(edmProperty.TypeUsage),
                  code.Escape(edmProperty),
                  code.SpaceAfter(Accessibility.ForGetter(edmProperty)),
                  code.SpaceAfter(Accessibility.ForSetter(edmProperty)));
}

Antonio Gabriele

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Accepted Answer

You can do this by specifying a metadata type that mirrors the properties and is used simply for attribution.

[MetadataType(typeof(Dinner_Validation))] 
public partial class Dinner 
{} 

public class Dinner_Validation 
{ 
    [Required] 
    public string Title { get; set; } 
}

Steve Smith blogs about it here.

Unfortunately the above approach is brittle to refactoring. Another option is to use the new POCO entities. These avoid compile-time code generation altogether as far as I can tell. I haven't used them yet so can't comment on any pitfalls or tradeoffs.

Adding custom property attributes in Entity Framework code

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Fastest Entity Framework Extensions

Accepted Answer

Popular Answer

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