Access to Many-to-Many table

Question

I have two tables, Project and BOM. Their relationship is many-to-many.

When I check my Migration class, I can see the below code that was automatically generated.

CreateTable(
    "dbo.ProjectBOMs",
    c => new
        {
            Project_Id = c.Int(nullable: false),
            BOM_Id = c.Int(nullable: false),
        })
    .PrimaryKey(t => new { t.Project_Id, t.BOM_Id })
    .ForeignKey("dbo.Projects", t => t.Project_Id, cascadeDelete: true)
    .ForeignKey("dbo.BOMs", t => t.BOM_Id, cascadeDelete: true)
    .Index(t => t.Project_Id)
    .Index(t => t.BOM_Id);

However, when I try to access this table using the following method, it's not showing up.

using(var db = new ApplicationDbContext())
{
    db.ProjectBOMs //<== there's no ProjectBOMs in db
}

Since ProjectBOMs table has already been automatically generated, do I have to write the following code again to be able to access the table?

modelBuilder.Entity<Project>()
    .HasMany<BOM>(x => x.BOMs)
    .WithMany(x => x.Projects)
    .Map(x =>
    {
        x.MapLeftKey("Project_Id");
        x.MapRightKey("BOM_Id");
        x.ToTable("ProjectBOMs");
    });

score 0 · Answer 1 · edited May 23 '17 at 11:46

0

I think the issue might be that the table isn't an entity in itself in your model, it's just the result of how the many-many relationship between Project and BOM is represented in a SQL database (i.e. with a joining table).

Do you need to access it because you need additional columns in the table? If so this question and the top voted answer look pretty useful.

edited May 23 '17 at 11:46

Community

1
1

answered Jan 03 '17 at 19:34

Parrybird

800
11
18

score 0 · Accepted Answer · answered Jan 03 '17 at 19:39

The if the table ProjectBOMs consists only of the Forign Key columns to Projects and BOMs then the table is NOT imported. It will result in a Project Collection on the BOMS and a BOM Collection on Projects, but will not be available as a stand alone entity.

Access to Many-to-Many table

2 Answers2