Question

I trying to map my classes to existing database, but failed in part of foreign keys declaration. Actually, I do not want to have field-foreign key, but only navigation proerty.
Here is models:

public class Template : BaseNamedType
{
    //One template may has multiple TemplateSection
    public virtual ICollection<TemplateSection> TemplateSection { get; set; }
    ...........
}

//Custom mapping class. I have field Order, without it mapping is simple
public class TemplateSection : BaseType
{
    public virtual int Order { get; set; }
    //Here is one-to-many relation, this field is required
    public virtual Template Template { get; set; }
    //Here is one-to-many relation, this field is required
    public virtual Section Section { get; set; }
}

public class Section : BaseNamedType
{
    //One section may be referenced by multiple TemplateSection
    public virtual ICollection<TemplateSection> SectionTemplates { get; set; }
    ...........

}

Here is my database creation script:

CREATE TABLE [templates]
(
    [id]           INT NOT NULL IDENTITY(1, 1),
    [name]         NVARCHAR(300) NOT NULL,
);

GO;

CREATE TABLE [sections_to_templates]
(
    [section_id]  INT NOT NULL,               //FK to [sections]
    [template_id] INT NOT NULL,               //FK to [templates]
    [order]       INT NOT NULL DEFAULT(0)
);

GO

CREATE TABLE [sections]
(
    [id]           INT NOT NULL IDENTITY(1, 1),
    [name]         NVARCHAR(300) NOT NULL,
);

GO

And here in my models binding code, I am absoulte not sure that it is correct:

modelBuilder.Entity<Template>()
    .HasKey(t0 => t0.Id)
    .Map(m => m.ToTable("templates"))
    .Property(x => x.Id)
    .HasColumnName("id")
    .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity)
    .IsRequired();
modelBuilder.Entity<Template>()
    .HasMany(t0 => t0.TemplateSection)
    .WithRequired(t1 => t1.Template)
    .Map(??????????????????)

modelBuilder.Entity<TemplateSection>()
    .HasKey(t0 => t0.Id)
    .Map(m => m.ToTable("sections_to_templates"))
    .Property(x => x.Id)
    .HasColumnName("id")
    .HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity)
    .IsRequired();
modelBuilder.Entity<TemplateSection>()
    .HasRequired(t0 => t0.Template)
    .WithMany(t1 => t1.TemplateSection)
    .Map(m => m.MapKey("template_id"));
modelBuilder.Entity<TemplateSection>()
    .HasRequired(t0 => t0.Section)
    .WithMany(t1 => t1.SectionTemplates)
    .Map(m => m.MapKey("section_id"));
//How to describe Section class????

Answer 1

You are almost done in my opinion:

• Remove the second mapping block, it is redundant because the relationship is already covered in the fourth mapping block.

• You can remove the IsRequired() mappings because non-nullable properties can only be required.

• You can remove the HasDatabaseGeneratedOption(DatabaseGeneratedOption.Identity) mappings because integer keys are database generated identities by default.

• For the string properties Name you can add:

  modelBuilder.Entity<Template>()
      .Property(x => x.Name)
      .HasColumnName("name")
      .HasMaxLength(300)
      .IsRequired();
  // the same for Section
  

• “How to describe Section class????“: Exactly the same way as your first mapping block.