Class map setting with Fluent NHibernate

Question

I'm new to using NHibernate and I struggled to find clear examples online of how to create a ClassMap for a stored procedure without using XML for the mappings. I recently got this working using the Fluent interfaces and wanted to share what I've learned.

The stored procedure in question returns an object like this:

public class ProductCategoryNavigation
{
    public virtual int CategoryId { get; protected set; }
    public virtual int CategoryNodeId { get; set; }
    public virtual int ParentCategoryNodeId { get; set; }
    public virtual string Name { get; set; }
    public virtual string Title { get; set; }
    public virtual string SeoUrl { get; set; }
    public virtual bool IsActive { get; set; }
    public virtual int DisplayOrder { get; set; }
    public virtual int ProductCount { get; set; }
}

So, how do I create a ClassMap that NHibernate will use to map the result of a stored procedure to this object?

Answer 1

The ClassMap looks like this:

public sealed class ProductCategoryNavigationMap : ClassMap<ProductCategoryNavigation>
{
    public ProductCategoryNavigationMap()
    {
        ReadOnly();

        // Set "CategoryId" property as the ID column. Without this, 
        // OpenSession() threw an exception that the configuration was invalid
        Id(x => x.CategoryId);
        Map(x => x.CategoryNodeId);
        Map(x => x.ParentCategoryNodeId);
        Map(x => x.Name);
        Map(x => x.Title);
        Map(x => x.SeoUrl);
        // The column name returned from the sproc is "VisibleInd", 
        // so this is here to map it to the "IsActive" property
        Map(x => x.IsActive).Column("VisibleInd"); 
        Map(x => x.DisplayOrder);
        Map(x => x.ProductCount);
    }
}

The call to the stored procedure looks like this:

public List<NavigationViewModel> GetNavigationViewModel(int portalId, int localeId)
{
    const string sql = "EXEC [dbo].[Stored_Procedure_Name] @PortalId=:PortalId, @LocaleId=:LocaleId";
    return _session.CreateSQLQuery(sql)
                .AddEntity(typeof(ProductCategoryNavigation))
                .SetInt32("PortalId", portalId)
                .SetInt32("LocaleId", localeId)
                .List<ProductCategoryNavigation>()
                .Select(x => new NavigationViewModel
                                 {
                                     CategoryId = x.CategoryId,
                                     CategoryNodeId = x.CategoryNodeId,
                                     ParentCategoryNodeId = x.ParentCategoryNodeId,
                                     Name = x.Name,
                                     Title = x.Title,
                                     SeoUrl = x.SeoUrl,
                                     IsActive = x.IsActive,
                                     DisplayOrder = x.DisplayOrder,
                                     ProductCount = x.ProductCount
                                 })
                .ToList();
}

The AddEntity calls says what Entity class to map the results to, which will use the ProductCategoryNavigationMap defined above:

.AddEntity(typeof(ProductCategoryNavigation))

If you look carefully at the value of the "sql" variable, you'll see two parameters:

1. :PortalId
2. :LocaleId

Those are set by making calls to:

.SetInt32("PortalId", portalId)
.SetInt32("LocaleId", localeId)

Then the call to .List<ProductCategoryNavigation>() provides us with an IList, which allows us to use LINQ to project whatever we want. In this case I'm getting a List of NavigationViewModel, which is currently the same as ProductCategoryNavigation but can change independently of the entity as needed.

I hope this helps other developers new to NHibernate!

Answer 2

Assuming you have NHibernate properly installed, you would create a new class where ever your are storing your class maps.

Create a class like:

public class PcnMap : ClassMap<ProductCategoryNavigation>
{
   Table("TableName");
   Id( x => x.CategoryId );
   Map( model => model.CategoryNodeId );
   // more like this for all your properties
}

Once you have that set up, you use your repositories as needed.

Keep in mind that is only a basic set up. The more complicated your database structure is, the more complicated your class map will get.