Lookup table with EF Codefirst - entity-framework

Question

I would like to create Resource and RelatedResources table with EF Code First as below:
Table Resource
int Id
string ResourceName
int Category
Table RelatedResource
int ResourceId
int RelatedResourceId
I tried as below but
Error: The ForeignKeyAttribute on property 'ResourceId' on type 'Models.ResourceRelated' is not valid. The navigation property 'Resource' was not found on the dependent type 'Models.ResourceRelated'. The Name value should be a valid navigation property name.
public class ResourceRelated
{
[ForeignKey("Resource")]
public int ResourceId { get; set; }
public virtual Resource Resoure { get; set; }
public virtual ICollection<Resource> RelatedResource { get; set; }
}
Kindly Advice!

Answer 1

If you want RelatedResource table, than you want many-to-many relationship. You can achieve this in next way
public class Resource
{
public int ResourceId { get; set; }
public string ResourceName { get; set; }
public int Category { get; set; }
[InverseProperty("Resoure")]
public virtual ICollection<RelatedResource> RelatedResource { get; set; }
[InverseProperty("ResourceRelated")]
public virtual ICollection<RelatedResource> ResourceRelated { get; set; }
}
public class RelatedResource
{
[Key]
[Column(Order = 1)]
[ForeignKey("Resoure")]
public int ResourceId { get; set; }
[Key]
[Column(Order = 2)]
[ForeignKey("ResourceRelated")]
public int ResourceRelatedId { get; set; }
public virtual Resource Resoure { get; set; }
public virtual Resource ResourceRelated { get; set; }
}
If you prefer do not work with RelatedResource in code, than you can do next
public class Resource
{
public int ResourceId { get; set; }
public string ResourceName { get; set; }
public int Category { get; set; }
public virtual ICollection<Resource> RelatedResource { get; set; }
public virtual ICollection<Resource> ResourceRelated { get; set; }
}
After you need next additional configuration
internal class ResourceConfiguration : EntityTypeConfiguration<Resource>
{
public ResourceConfiguration()
{
HasMany(s => s.ResourceRelated).WithMany(c => c.RelatedResource)
.Map(cs => {
cs.MapLeftKey("ResourceId");
cs.MapRightKey("RelatedResourceId");
cs.ToTable("RelatedResource"); }
);
}
}
And finally add this configuration
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
///other configuration code
modelBuilder.Configurations.Add(new ResourceConfiguration());
}
But if you want to have "resource tree" than you do not need RelatedResource table
public class Resource
{
public int ResourceId { get; set; }
public string ResourceName { get; set; }
public int Category { get; set; }
public int? ResourceRelatedId { get; set; }
public Resource ResourceRelated { get; set; }
[ForeignKey("ResourceRelatedId")]
public virtual ICollection<Resource> RelatedResource { get; set; }
}