I have the following simple domain model representing a hierarchy:
public class FolderHierarchyNode
{
public virtual Guid Id { get; private set; }
public virtual string Name { get; private set; }
public virtual FolderHierarchyNode Parent { get; set; }
ICollection<FolderHierarchyNode> _children = new
HashSet<FolderHierarchyNode>();
public virtual IEnumerable<FolderHierarchyNode> Children { get
{ return _children; } }
public FolderHierarchyNode() { }
}
I only need to track children, not the level in the hierarchy which I
should be able to do with this mapping:
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
assembly="MyApp.Domain" namespace="MyApp.Domain.FolderHierarchy">
<class name="FolderHierarchyNode" table="NODES">
<id name="Id" column="PK_NODES" type="System.Guid" unsaved-
value="00000000-0000-0000-0000-000000000000">
<generator class="guid" />
</id>
<property name="Name" column="NDELNAME" />
<many-to-one name="Parent" column="FK_NODES"
class="FolderHierarchyNode" not-null="true" />
<set name="_children" access="field" cascade="all-delete-orphan"
lazy="false">
<key column="FK_NODES" />
<one-to-many class="FolderHierarchyNode"/>
</set>
</class>
</hibernate-mapping>
I can then query for the parent node simply like this:
public FolderHierarchyNode Get()
{
using (var s = _sessions.OpenSession())
return s.Linq<FolderHierarchyNode>()
.ToArray()
.Single(n => n.Parent.IsNull());
}
This generates at first the following SQL:
SELECT
this_.PK_NODES as PK1_4_0_, this_.NDELNAME as NDELNAME4_0_,
this_.FK_NODES as FK3_4_0_
FROM NODES this_
The results of this query should already contain all the information
necessary to build up the object tree but then I get a plethora more
select statements (I assume to fetch the children of each node):
SELECT children0_.FK_NODES as FK3_1_, children0_.PK_NODES as PK1_1_,
children0_.PK_NODES as PK1_4_0_, children0_.NDELNAME as NDELNAME4_0_,
children0_.FK_NODES as FK3_4_0_ FROM NODES children0_ WHERE
children0_.fk_nod...@p0;@p0 = 106e707a-699c-4c7e-a625-f3add43c0aee
SELECT children0_.FK_NODES as FK3_1_, children0_.PK_NODES as PK1_1_,
children0_.PK_NODES as PK1_4_0_, children0_.NDELNAME as NDELNAME4_0_,
children0_.FK_NODES as FK3_4_0_ FROM NODES children0_ WHERE
children0_.fk_nod...@p0;@p0 = 89e18057-eabe-466f-b3e6-e1ce02c90bfd
....
etc.
What's the best way to get rid of these un-necessary sql calls? My
best guess is that I can drop the children from the mapping and in my
repository wire them up manually, but I'm hoping there's a more
integrated way to do this
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