Question

I’m having an issue with persisting a field which is in my were clause on a ManyToMany releationship, but doesn’t explicityly exist on the class mapping. Hard to explain but its the “is_expred” field in the below classes and mappings.

I have the following two classes:

public class Publication
{
    public virtual int Id {get; set;}

    public virtual string Name {get; set;}
}

public class Role
{
    public virtual int Id {get; set;}
    public virtual string Name {get; set;}

    public virtual IEnumerable<Publication> CurrentPublications {get; set;}

    public virtual IEnumerable<Publication> ExpiredPublications {get; set;}
}

Where a publication can exist in either or both the CurrentPublications and ExpiredPublications. (and no, I can’t put the expired field on the Publication, as its only expired for this particular role – it might be current on a different role)

The DB for this is:

role
{
    role_id     int (PK)
    role_name   varchar(50)
}

role_pub
{
    role_id     int (PK)
    pub_id      int (PK)
    is_expired  bit
}

pub
{
    pub_id      int (PK)
    pub_name    varchar(50)
}

And the fluent mapping:

public class RoleMapping : ClassMap<Role>
{
    public RoleMapping()
    {
        Table("role");
        Id(x => x.Id, "role_id").GeneratedBy.Identity();
        Map(x => x.Name, "role_name").Not.Nullable();

        HasManyToMany<Publication>(x => x.CurrentPublications)
            .Table("role_pub")
            .ParentKeyColumn("role_id")
            .ChildKeyColumn("pub_id")
            .Where("is_expired = 0")
            .LazyLoad();

        HasManyToMany<Publication>(x => x.ExpiredPublications)
            .Table("role_pub")
            .ParentKeyColumn("role_id")
            .ChildKeyColumn("pub_id")
            .Where("is_expired = 1")
            .LazyLoad();
    }
}


public class PublicationMapping : ClassMap<Publication>
{
    public PublicationMapping()
    {
        Table("pub");
        Id(x => x.Id, "pub_id").GeneratedBy.Identity();
        Map(x => x.Name, "pub_name").Not.Nullable();
    }
}

When I do the select on a role, the Current and Expired Publications are populated with the correct Publications, but when I add new publciations to either Current or Expired lists, it always saves the is_expired field as 0, which is the default value of “is_expired” in the DB.

Does anyone have any idea on wha tthe correct way of mapping this releationship and populating the “is_expired” field correctly?

Thanks for your help

Saan

Answer 1

the where only filters on SELECT but never fills up the columns on INSERT. you could introduce a class RolePublication which has the is_expired mapped

public class RolePublication
{
    public virtual Role Role {get; set;}
    public virtual Publication Publication {get; set;}
    public virtual bool IsExpired {get; set;}
}

public class Role
{
    ...
    internal protected virtual ICollection<RolePublication> Publications {get; set;}

    public virtual IEnumerable<Publication> CurrentPublications
    { get { return Publications.Where(rp => rp.IsExpired == false).Select(rp => rp.Publication); ) } }

    public virtual IEnumerable<Publication> ExpiredPublications
    { get { return Publications.Where(rp => rp.IsExpired == true).Select(rp => rp.Publication); ) } }
}