EntityFramework get related item by id or field - entity-framework

Question

I have two objects like:
public class Area : IEntity
{
public virtual int Id { get; set; }
public virtual int AreaTypeLookupId { get; set; }
[Column(TypeName = "varchar")]
[StringLength(100)]
public virtual string Name { get; set; }
[Column(TypeName = "varchar")]
[StringLength(2)]
public virtual string VMRegionCode { get; set; }
public virtual int GISPrimaryKeyId { get; set; }
public virtual string ConcatenatedGISAreaIds { get; set; }
public virtual int? ParentAreaId { get; set; }
public virtual int? ParentRegionAreaId { get; set; }
[Column(TypeName = "char")]
[StringLength(3)]
public virtual string CostCenterCode { get; set; }
[Column(TypeName = "varchar")]
[StringLength(64)]
public string CreatedByUserName { get; set; }
public DateTime CreatedDateTime { get; set; }
[Column(TypeName = "varchar")]
[StringLength(64)]
public string LastModifiedByUserName { get; set; }
public DateTime? LastModifiedDateTime { get; set; }
// Navigation properties
public virtual AreaTypeLookup AreaTypeLookup { get; set; }
}
public class AreaTypeLookup : IEntity
{
[Column("Id")]
public virtual int AreaTypeLookupId { get; set; }
[Column(TypeName = "varchar")]
[StringLength(100)]
public virtual string Name { get; set; }
[Column(TypeName = "varchar")]
[StringLength(10)]
public virtual string ShortName { get; set; }
public virtual int? AreaTypeLevelLookupId { get; set; }
public virtual int? OperationTypeLookupId { get; set; }
public virtual int? ParentAreaTypeLookupId { get; set; }
public bool IsAvailableToSetBudgetAgainst { get; set; }
public int DisplaySortOrder { get; set; }
public bool IsProtected { get; set; }
public DateTime? DeletedDateTime { get; set; }
public int? ManagedByServiceTypeLookupId { get; set; }
[Column(TypeName = "varchar")]
[StringLength(64)]
public string CreatedByUserName { get; set; }
public DateTime CreatedDateTime { get; set; }
[Column(TypeName = "varchar")]
[StringLength(64)]
public string LastModifiedByUserName { get; set; }
public DateTime? LastModifiedDateTime { get; set; }
}
What I want is to get all the areas where areatypelookupid = 3. For this area type the name is "region"
What is the best way to get the areas for code maintainability:
This:
var areas = _unitOfWork.AreaRepository.GetAll().Where(x => x.AreaTypeLookupId == 3);
or this:
var areas = _unitOfWork.AreaRepository.GetAll().Where(x => x.AreaTypeLookup.Name == "region");
where I guess "region" should really becoming from a resources file.

Answer 1

Typically, you will want to use the primary key as that should be immutable. However, if you can guarantee that the lookup name is not going to change, then searching by name would be tolerable. The reason I say tolerable is because running queries off of the primary key will be more efficient on the database, on top of the immutability.