Asp.Net MVC Codefirst Model Relation to the Same Model

Question

I have a model and i want to put an extra field which can be populated form the same model. IE: Categories and and sub-categories.

In my example, visitor can add an filetype but if file type is under an another file type, he can choose, But i cant work it out. Below you can see my model.

 public class HrFileType
    {
        [Key]
        public int Id { get; set; }
        [Display(Name = "Dosya Adı")]
        public int Name { get; set; }

        public int? HrFileTypeId { get; set; }
        public virtual HrFileType HrFileType2 { get; set; }
    }

Lin · Accepted Answer · 2014-02-17 13:44:36Z

1

You just need to add a ForeignKeyAttribute like below:

public class HrFileType
{
    [Key]
    public int Id { get; set; }
    [Display(Name = "Dosya Adı")]
    public int Name { get; set; }

    public int? HrFileTypeId { get; set; }

    [ForeignKey("HrFileTypeId")]
    public virtual HrFileType HrFileType2 { get; set; }
}

You can also use fluent API to achieve this:

public class HrFileType
{
    [Key]
    public int Id { get; set; }
    [Display(Name = "Dosya Adı")]
    public int Name { get; set; }

    public int? HrFileTypeId { get; set; }
    public virtual HrFileType HrFileType2 { get; set; }
}

public class YourDbContext : DbContext
{
    public DbSet<HrFileType> HrFileTypes { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        //
        modelBuilder.Entity<HrFileType>()
                    .HasOptional(c => c.HrFileType2)
                    .WithMany()
                    .HasForeignKey(c => c.HrFileTypeId);
    }
}

answered Feb 17, 2014 at 13:44

Lin

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1 Comment

umki Over a year ago

Thank you, this is what i am trying to do :)

Heberda · Accepted Answer · 2014-02-17 13:29:04Z

0

Have you tried listing the other file types?

 public class HrFileType
    {
        [Key]
        public int Id { get; set; }
        [Display(Name = "Dosya Adı")]
        public int Name { get; set; }

        public List<HrFileType> RelatedTypes { get; set; }
    }

then using Entity Frameworks fluent API in the DbContext, try explicitly declaring a many to many map.

modelbuilder.Entity<HrFileType>().HasMany(x => x.RelatedTypes).WithMany();

I'd be very interested to see if this works. It's the only logical solution I can think of without having some kind of parent class.

edited Feb 17, 2014 at 13:29

answered Feb 17, 2014 at 12:49

Heberda

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4 Comments

umki Over a year ago

Sorry not working,Error 1 The type arguments for method 'System.Data.Entity.ModelConfiguration.EntityTypeConfiguration<ModulericaV1.Areas.Hr.Models.HrFileType>.HasMany<TTargetEntity>(System.Linq.Expressions.Expression<System.Func<ModulericaV1.Areas.Hr.Models.HrFileType,System.Collections.Generic.ICollection<TTargetEntity>>>)' cannot be inferred from the usage. Try specifying the type arguments explicitly. c:\users\umutg\documents\visual studio 2013\Projects\ModulericaV1\ModulericaV1\Models\ModulericaDbContext.cs 20 9 ModulericaV1

Heberda Over a year ago

I've just made a minor change to the fluent api which you could test. My theory behind the many to many relationship is to force EF to create a separate table. Out of interest how many related file types could there be?

umki Over a year ago

actually , i do not want it to create a separate file. It can be more tan 30 :S

Heberda Over a year ago

Are you persisting to a sql database? It wouldn't be a new file, only a table holding the relational mapping. Did you try the update?

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