CODEWITHSUNDEEP
c#entity-frameworkentity-framework-4
Will
Will

Reputation: 63

EntityFramework Fluent API map a class as a composite key

I have a class that has a composite key defined as a seperate class.

public class ClassA : Entity
{
    public virtual ClassACompositeKey CompositeKey { get; set; }
}

public class ClassACompositeKey
{
    public int ThisId { get; set; }

    public int ThatId { get; set; }

    public int OtherId { get; set; }
}

Having some difficulty mapping this using fluent api for entity framework. I have tried creating a complex type configuration for the composite class with no luck. When I attempt the mapping as 

this.HasKey(k => new { k.CompositeKey.ThisId, k.CompositeKey.ThatId, k.CompositeKey.OtherId });

I get an error stating that

The properties expression 'k => new <>f__AnonymousType2 (ThisId = k.CompositeKey.ThisId, ThatId = k.CompositeKey.ThatId, OtherId = k.CompositeKey.OtherId)' is not valid. The expression should represent a property.

I'm somewhat new to EF and Fluent API so I don't even know if this is going to be possible. Any help would be appreciated.

Upvotes: 2

Views: 500

Answers (1)

Slauma
Slauma

Reputation: 177133

Unfortunately it's not supported. Key properties must have primitive types (int, long, string, Guid, DateTime, etc.) and be directly inside the entity class without a wrapping class around them. So you must define a composite key like so:

public class ClassA : Entity
{
    public int ThisId { get; set; }

    public int ThatId { get; set; }

    public int OtherId { get; set; }
}

... with the Fluent mapping:

this.HasKey(k => new { k.ThisId, k.ThatId, k.OtherId });

Upvotes: 3

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