Fluent Automapper issue with tag creation - automapper

Question

POST EDITED - see edit below
I have a query about the FLuent Automapping which is used as part of the SHarp Architecture. Running one of the tests cases will generate a schema which I can use to create tables in my DB.
I'm developing a site with Posts, and Tags associated with these posts. I want a tag to be able to be associated with more than one post, and for each post to have 0 or more tags.
I wanting to achieve a DB schema of:
Post {Id, Title, SubmitTime, Content}
Tag {Id, Name}
PostTag {PostId, TagId}
Instead, I'm getting:
Post {Id, Title, SubmitTime, Content}
Tag {Id, Name, PostID (FK)}
I'm using sharp architecture, and may classes look as follows (more or less):
public class Post : Entity
{
[DomainSignature]
private DateTime _submittime;
[DomainSignature]
private String _posttitle;
private IList<Tag> _taglist;
private String _content;
public Post() { }
public Post(String postTitle)
{
_submittime = DateTime.Now;
_posttitle = postTitle;
this._taglist = new List<Tag>();
}
public virtual DateTime SubmitTime { get { return _submittime; } private set { _submittime = value; } }
public virtual string PostTitle { get { return _posttitle; } private set { _posttitle = value; } }
public virtual string Content { get { return _content; } set { _content = value; } }
public virtual IList<Tag> TagList { get { return _taglist; } set { _taglist = value; } }
public class Tag : Entity
{
[DomainSignature]
private String _name;
public Tag() { }
public Tag(String name)
{
this._name = name;
}
public virtual String Name
{
get { return _name; }
private set { _name = value; }
}
public virtual void EditTagName(String name)
{
this.Name = name;
}
}
I can see why it's gone for the DB schema set up that it has, as there will be times when an object can only exist as part of another. But a Tag can exist separately.
How would I go about achieving this? I'm quite new to MVC, Nhibernate, and SHarp architecture, etc, so any help would be much appreciated!
EDIT*
OK, I have now adjusted my classes slightly. My issue was that I was expecting the intermediate table to be inferred. Instead, I realise that I have to create it.
So I now have (I've simplified the classes a bit for readability's sake.:
class Post : Entity
{
[DomainSignature]
String Title
[DomainSignature]
DateTime SubmitTime
IList<PostTag> tagList
}
class Tag : Entity
{
[DomainSignature]
string name
}
class PostTag : Entity
{
[DomainSignature]
Post post
[DomainSignature]
Tag tag
}
This gives me the schema for the intermediate entity along with the usual Post and Tag tables:
PostTag{id, name, PostId(FK)}
The problem with the above is that it still does not include The foreign key for Tag. Also, should it really have an ID column, as it is a relational table? I would think that it should really be a composite key consisting of the PK from both Post and Tag tables.
I'm sure that by adding to the Tag class
IList<PostTag> postList
I will get another FK added to the PostTag schema, but I don't want to add the above, as the postList could be huge. I don't need it every time I bring a post into the system. I would have a separate query to calculate that sort of info.
Can anyone help me solve this last part? Thanks for your time.

Answer 1

Ok, I'd been led to believe that modelling the composite class in the domain was the way forward, but I finally come across a bit of automapper override code which creates the composite table without me needing to create the class for it, which was what I was expecting in the first place:
public class PostMappingOverride
: IAutoMappingOverride
{
public void Override(AutoMapping map)
{
map.HasManyToMany(e => e.TagList)
.Inverse()
.Cascade.SaveUpdate();
}
}
This will now give me my schema (following schema non simplified):
create table Posts (
Id INT not null,
PublishTime DATETIME null,
SubmitTime DATETIME null,
PostTitle NVARCHAR(255) null,
Content NVARCHAR(255) null,
primary key (Id)
)
create table Posts_Tags (
PostFk INT not null,
TagFk INT not null
)
create table Tags (
Id INT not null,
Name NVARCHAR(255) null,
primary key (Id)
)
alter table Posts_Tags
add constraint FK864F92C27E2C4FCD
foreign key (TagFk)
references Tags
alter table Posts_Tags
add constraint FK864F92C2EC575AE6
foreign key (PostFk)
references Posts
I think the thrower is that I've been looking for a one-to-many relationship, which it is, but it is called HasManytoMAny here...