Question

Is there any way to get dataanotations for my models directly from my database?
I have a database with lot’s of data and tables, so i am generating my model with entity framework from database, so i get classes, but i want to know can entity framework or some other orm get properities and constrains directly from database and put them in classes as data anotation like [required] or [datatype(datatype.emailadress)]

Answer 1

Yes. You can inherit the ModelMetadataProvider class:

public class LocalizedModelMetadataProvider : DataAnnotationsModelMetadataProvider
{

    protected override ModelMetadata CreateMetadata(IEnumerable<Attribute> attributes, Type containerType,
                                                    Func<object> modelAccessor, Type modelType, string propertyName)
    {
        var metadata = base.CreateMetadata(attributes, containerType, modelAccessor, modelType, propertyName);
        if (containerType == null || propertyName == null)
            return metadata;

        // Load all metadata from your database here.

        return metadata;
    }

}

I’m creating a project called Griffin.MvcContrib which is almost done and has a administration area where you can handle all localization (zero-code) for both models and validation messages.

By using it you can just implement the following interface to get support for your database:

// the actual code file has detailed explanations of each method.
public interface ILocalizedStringProvider
{
    string GetModelString(Type model, string propertyName);
    string GetModelString(Type model, string propertyName, string metadataName);
    string GetValidationString(Type attributeType);
    string GetEnumString(Type enumType, string name);

}

Update

Where is not important. And you do not have to use DataAnnotation attributes on your models (the [Display] attribute). I just inherit the DataAnnotationsModelMetadataProvider to be able to use the attributes.

1. Create the class anywhere.
2. Read from the database
3. Configure MVC to use it in global.asax

Example:

 ModelMetadataProviders.Current = new YourModelMetadataProvider();