CODEWITHSUNDEEP
c#entity-framework
Jimmyt1988
Jimmyt1988

Reputation: 21166

One to many relationship is putting relationship explicitly on child

If I have the following:

class Project
{
    ...
    public virtual IList<URL> URLs {get;set;}
}

class URL
{
    ...
    public virtual Project Project {get;set;}
}

The database created adds ProjectID to the URLs database table...

How do I force entity to create the relationship table for me to remove that dependency on URL without having to declare a new entity called ProjectURL like so:

public class ProjectURL
{
    [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int ProjectURLID { get; set; }

    public URL URL { get; set; }
    public Project Project{ get; set; }
}

What I currently have:

Projects 

ProjectID |
---------------------
64        |

URLs

URLID     | ProjectID |
---------------------
13        | 64

What I want to have:

Projects 

ProjectID |
---------------------
64        |

URLs

URLID   | 
---------------------
13      |

Project_URLs

URLID   | ProjectID
---------------------
13      | 64

Upvotes: 0

Views: 37

Answers (1)

Kryptos
Kryptos

Reputation: 875

You will need to configure the mapping for your URL entity so that it is splitted into two tables. One table will be the URL, the other will also contain the additional properties (like the foregin key to Project). Take a look at the Map method.

Your mapping configuration will look like:

class URLMap : EntityTypeConfiguration<URL>
{
    public URLMap()
    {
        Map(m =>
        {
            m.Properties(p => new {p.ID, p.Project});
            m.ToTable("Project_URLs");
        });
        Map(m =>
        {
            m.Properties(p => new
            {
                p.ID,
                // all other properties separated by ,
            });
            m.ToTable("URLs");
        });
        HasKey(p => p.ID);
    }
}

Be aware of defining the same primary key for both tables (in the above example I assumed an ID property).

edit: In cas you don't know what to do with the mapping configuration class. You have to add an instance of this class to the override of DbContext.OnModelCreating:

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
    modelBuilder.Configurations.Add(new URLMap());
}

Upvotes: 1

Related Questions