MVC3 Validation with Entity Framework Model/Database First

Question

I want to use MVC 3 and the Entity Framework for my application.

The model will be stored in a different assembly to the MVC app.

The choice I'm making is either to use the EF to generate my entities or to use code first.

With code first, I can decorate members with [Required] etc... But how would I go about adding those attributes if EF has generated entities from the DB?

Having EF generate my entities will save a lot of time, but I want MVC to auto populate the validation depending on how I've decorated my members. Does this make sense? If so, how would I do that?

archil · Accepted Answer · 2011-07-21 11:30:17Z

11

In that case, MetadataTypeAttribute is used. You can combine it with partial classes to achieve desired results

And by the way, in your place i would do more research when deciding between using Database First and Code First designs. That all is not about saving time when generating entities, there's much more difference between those two approaches. For the time saving purpose, you can use EF Power Tools to generate code first entities from database - simple.

edited Jul 21, 2011 at 11:30

answered Jul 21, 2011 at 11:13

archil

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9 Comments

Paul Over a year ago

Thanks, When I do that I get Ambiguous name error. Here is what I've got in my partial class (the entity is called Item in the model):

Paul Over a year ago

[MetadataType(typeof(Item))] public partial class Item { [StringLength(10), Required] public string MaterialName { get; set; } }

jim tollan Over a year ago

paul, the ambiguity 'could' be to do with the pre-existing edmx ef file maybe??

archil Over a year ago

Generally, naming convention for metadata classes is [className]Metadata. For Item entity, good naming for its metadata would be ItemMetadata. Try this to avoid ambiguous name conflicts

Diego Over a year ago

but that approach makes necessary to edit the class generated by EF, whihc is not good because the changes would be overwritten if the class is re-generated..

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Tomas Aschan · Accepted Answer · 2011-07-21 11:49:39Z

2

Better than auto generating your entities, I recommend you to use Code First or mapping an existing database to POCO's classes (not generating the entities, just creating them by hand and mapping them to the existing database)

Scottgu wrote about using EF "Code First" with an existing database.

edited Jul 21, 2011 at 11:49

Tomas Aschan

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answered Jul 21, 2011 at 11:15

Jesus Rodriguez

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Comments

NicolasKittsteiner · Accepted Answer · 2013-12-27 15:51:06Z

Check this out: In your model template (file with extension model.tt) you can hack this template for generating decorators, in this example I add the [Required] decorator plus an error message

var simpleProperties = typeMapper.GetSimpleProperties(entity);
if (simpleProperties.Any())
{
    foreach (var edmProperty in simpleProperties)
    {
        if(!edmProperty.Nullable)
        {#>
[Required(ErrorMessage="<#=String.Format("The field {0} is required",edmProperty.ToString())#>")]<#
        }#>
<#=codeStringGenerator.Property(edmProperty)#><#
    }
}

So the result is something like this

    [Required(ErrorMessage="The field Id is required")]
    public long Id { get; set; }

PS: You can also add the using System.ComponentModel.DataAnnotations; by editing the template.

Hope this can help you up.

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