Fluent NHibernate mapping properties coming from an interface in one place

Question

If many classes implement the same interface(s), is it possible to map those interface properties in one place? There's more code @ pastebin

You can see here that classes have some common interfaces (but not all to make common base class) and I had to repeat mappings.

public class PostMapping : SubclassMap<Post>
{
    public PostMapping()
    {
        Map(x => x.Text, "Text");
        // coming from IMultiCategorizedPage
        HasManyToMany(x => x.Categories).Table("PageCategories").ParentKeyColumn("PageId").ChildKeyColumn("CategoryId").Cascade.SaveUpdate();
        // coming from IMultiTaggedPage
        HasManyToMany(x => x.Tags).Table("PageTags").ParentKeyColumn("PageId").ChildKeyColumn("TagId").Cascade.SaveUpdate();
        // coming from ISearchablePage
        Map(x => ((ISearchablePage)x).SearchIndex, "SearchIndex").LazyLoad();
    }
}
public class ArticleMapping : SubclassMap<Article>
{
    public ArticleMapping()
    {
        Map(x => x.Text, "Text");
        // coming from ISingleCategorizedPage
        References(x => x.Category, "CategoryId");
        // coming from IMultiTaggedPage
        HasManyToMany(x => x.Tags).Table("PageTags").ParentKeyColumn("PageId").ChildKeyColumn("TagId").Cascade.SaveUpdate();
        // coming from ISearchablePage
        Map(x => ((ISearchablePage)x).SearchIndex, "SearchIndex").LazyLoad();
    }
}

Sixto Saez · Accepted Answer · 2011-02-28T16:43:45.833

If C# had complete multiple inheritance instead of just multiple interface inheritance then this would be easy. It seems the closest would be creating a single wrapping interface for a mapping base class to hold your common elements. Then, you could create table specific mapping classes that inherit from it. Something along the lines of this code:

public class BasePageMapping : SubclassMap<IPage> //IPage could inherit: IMultiTaggedPage, ISearchablePage
{
    public BasePageMapping()
    {
        Map(x => x.Text, "Text");
        // coming from IMultiTaggedPage
        HasManyToMany(x => x.Tags).Table("PageTags").ParentKeyColumn("PageId").ChildKeyColumn("TagId").Cascade.SaveUpdate();
        // coming from ISearchablePage
        Map(x => ((ISearchablePage)x).SearchIndex, "SearchIndex").LazyLoad();
    }
}

public class PostMapping : BasePageMapping
{
    public PostMapping()  // don't need to specify : base() because it happens automatically
    {
        Table("the specific table");

        HasManyToMany(x => x.Categories).Table("PageCategories").ParentKeyColumn("PageId").ChildKeyColumn("CategoryId").Cascade.SaveUpdate();

        //Other table specific mappings:
    }
}

Fluent NHibernate mapping properties coming from an interface in one place

1 Answers1