Data Annotations with Entity Framework 5.0 (database first)

Question

What is the best way to use data annotations for validation if I'm using an Entity Framework (v5.0) database first approach?

This is my partial class created by Entity Framework:

//------------------------------------------------------------------------------ // <auto-generated> // This code was generated from a template. // // Manual changes to this file may cause unexpected behavior in your application. // Manual changes to this file will be overwritten if the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ using System.ComponentModel.DataAnnotations; namespace ACore { using System; using System.Collections.Generic; public partial class PayrollMarkup_State { [UIHint("StatesEditor")] // <-- I added this line but it will be overwritten public string State { get; set; } public Nullable<float> MaintenancePercentage { get; set; } public Nullable<float> OfficePercentage { get; set; } } }

I tried this with no success....

Entity Framework generated file: 'PayrollMarkup_State.cs'

//------------------------------------------------------------------------------ // <auto-generated> // This code was generated from a template. // // Manual changes to this file may cause unexpected behavior in your application. // Manual changes to this file will be overwritten if the code is regenerated. // </auto-generated> //------------------------------------------------------------------------------ using System.ComponentModel.DataAnnotations; namespace ACore { using System; using System.Collections.Generic; public partial class PayrollMarkup_State { public string State { get; set; } public Nullable<float> MaintenancePercentage { get; set; } public Nullable<float> OfficePercentage { get; set; } } }

I then created this file in a different directory: 'PayrollMarkup_state.cs'

using System; using System.Collections.Generic; using System.ComponentModel.DataAnnotations; using System.Linq; using System.Web; namespace ACore.Models { [MetadataType(typeof(PayrollMarkupMetadata))] public partial class PayrollMarkup_State { } public class PayrollMarkupMetadata { [UIHint("StatesEditor")] public string State; // Has to have the same type and name as your model } }

GalacticCowboy · Accepted Answer · 2013-03-25 18:14:26Z

23

Although it's somewhat painful, you need to create a class to use as the MetadataType for your model class.

[MetadataType(typeof(PayrollMarkupMetadata)) public partial class PayrollMarkup_State { ... } public class PayrollMarkupMetadata { [UIHint("StatesEditor")] public string State; // Has to have the same type and name as your model // etc. }

answered Mar 25, 2013 at 18:14

GalacticCowboy

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3 Comments

JYL Over a year ago

Does this really work if you declare a field instead of a property in your metadata class ?

GalacticCowboy Over a year ago

@JYL yes, it doesn't look at whether it's a field or property, it's just an indirection mechanism. "Find this thing in that other class with this type and name, and apply these attributes to it."

brian s Over a year ago

Thanks to Julie Lerman for linking me to this blog post. More detail on using GalacticCowboy's approach here. Ardalis - Adding attributes to generated classes

Moho · Accepted Answer · 2013-03-25 18:31:55Z

You have a namespace problem - you have defined two different PayrollMarkup_State classes, one under the ACore namespace and one under the ACore.Models namespace. Change the namespace to ACore (from ACore.Models) in the file containing the metadata type definition.

You're right, but @GalacticComboy has the original good answer.

Shivam Srivastava · Accepted Answer · 2015-01-20 12:24:11Z

You can use a partial metadata class

http://www.asp.net/mvc/overview/getting-started/database-first-development/enhancing-data-validation

IAbstract · Accepted Answer · 2017-05-26 20:40:47Z

I used two additional classes: Map and Meta, here is my map:

namespace Whatever.Models { [MetadataType(typeof(ThisMeta))] public partial class This { } }

now here is meta class:

using System.ComponentModel; using System.ComponentModel.DataAnnotations; namespace Whatever.Models { public class ThisMeta { [DisplayName("")] public int UID { get; set; } } }

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