Dataannotation with EF

Question

I have tried DataAnnotation as described here, but it does not work for me.

I have a table with the following structure

Table - Category
    id int (pk not null)
    CategoryName varchar(100) (null)

I already created my edmx file and all.

I have created the Category.cs file also like below.

[MetadataType(typeof(CategoryMetaData))]
public partial class Category
{
}

public class CategoryMetaData
{
    [Required(ErrorMessage = "Category Name is required.")]
    public object CategoryName;
}

But my validations are not working.

Is there anything I've missed?

I tried to insert the data with out filling and it inserted a null value. — Mukesh, Apr 08 '11 at 07:46
How did you create the data, via ASP.Net mvc or simple assignment? — archil, Apr 08 '11 at 08:17
To make sure that you've got the Data Annotations part working correctly, create a totally new class unrelated to your entities that has an annotation, and try to use that. If it doesn't work either, then that'll give you a starting point. — Tridus, Apr 08 '11 at 11:43

score 2 · Answer 1 · answered Nov 07 '12 at 02:56

I have found that ObjectContext does not work with DataAnnotations. You have to switch to using DbContext, then it works. Download the EF 4.x DbContext T4 file and try it on your model. Not sure why this is true, was hoping an expert would chime in.

score 0 · Answer 2 · answered Apr 08 '11 at 08:01

0

CategoryName in CateogryMetaData should be a property and has the same type as the original property. Try this:

public class CategoryMetaData
{
    [Required(ErrorMessage = "Category Name is required.")]
    public string CategoryName {get;set;}
}

answered Apr 08 '11 at 08:01

Quang Vo

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Just double check, is your Category partial class in the same namespace as the generated one? – Quang Vo Apr 08 '11 at 08:10
Yes. The edmx and the partial class are in the same directory and namespace. – Mukesh Apr 08 '11 at 08:17

score 0 · Accepted Answer · edited May 23 '17 at 12:02

UPD Solution here.

Before validating, you need to manually register the metadata class

==================

I suppose this problem is related to proxy classes, which EF generates for your entities. You can check this easily in runtime: just see GetType().FullName.

If attribute is marked as non-inheritable, it won't be applied in inherited class. And proxy classes derive from entity classes, so non-inheritable attributes are lost.

I'm trying to use DataAnnotations in WebForms project by checking attributes by hand. But neither

System.ComponentModel.DataAnnotations.Validator.TryValidateObject(entity, new ValidationContext(value, null, null), results, true);

nor

PropertyInfo[] properties = value.GetType()
                 .GetProperties(System.Reflection.BindingFlags.Public | System.Reflection.BindingFlags.Instance);

var validationProperties = properties.Select(prop => new
        {
            Property = prop,
            ValidationAttributes = Attribute.GetCustomAttributes(prop, typeof(ValidationAttribute), true)
        }).Where(valProp => valProp.ValidationAttributes.Any());

doesn't work. I've tried these code with simple class not related to EF, and all DataAnnotations attributes were found and checked correctly.

[MetadataType(typeof(TestValidObject_Metadata))]
public class TestValidObject
{
    public string IdName { get; set; }
}

public class TestValidObject_Metadata
{
    [Required, DisplayName("Id name")]
    public object IdName { get; set; }
}

RequiredAttribute's definition is

[AttributeUsageAttribute(AttributeTargets.Property|AttributeTargets.Field|AttributeTargets.Parameter, AllowMultiple = false)]
public class RequiredAttribute : ValidationAttribute

and by default it becomes inheritable attribute. And I don't know why

Attribute.GetCustomAttributes(prop, typeof(ValidationAttribute), true)  
// true specifies to also search the ancestors of element for custom attributes.

doesn't catch it.

Any ideas are welcome.

Dataannotation with EF

3 Answers3