Hi,

I have what should be a relatively simple issue but I am struggling to resolve it.

There are 2 tables in my data model: Group and Category. There is a one-to-many relationship....one Group can have many Categories, and a Category can be in one group.

I've got the same 2 classes in my domain model, standard stuff.

Now, I need to write some unit tests for a controller class which uses instances of Group and Category. But the key here is that they are unit tests so I would use a mocking framework (NMock2 in this case) to create mock instances of the domain objects.

So standard practice is to have your domain objects implement an interface, and use the interface to create the mock instances.

So I created an IGroup and ICategory. ICategory has an accessor for it's group. Now I'm working with interfaces the ICategory.Group returns an IGroup rather than a group:



This is all fine and my unit tests with the mock instances of ICategory and IGroup all work fine.

HOWEVER....now I am unable to do any data access with the Category and Group objects...I get the following NHibernate error:



Here's my mapping file for Category:



I tried to find some info on this but didn't really find a good example of a domain model implemented using standard interfaces. I did find some stuff but it had all sorts of IoC and Castle Windsor in there which was way over the top for what I want. I just want to use simple interfaces!

I did find another sample which included a "proxy" attribute on the class element. So I tried this:



but that made no difference.

Can anybody help? Can my domain model be coded against interfaces?

Use abstract class instead of interface.

Code:


Mapping:

Ah, I NEED the interface in order to generate a dynamic mock!

You can use only classes for object mapping.

Surely it's a common scenario to want to use domain objects which are coded against an interface?

What if you have pre-existing domain model coded against an interface? Or a domain model under the control of another team?

It is scenario does not approach for NHibernate.
For pre-existing domain model you can use object-wrapper.

I just found out I can use Interfaces for my domain model.

Turns out all I needed was to explicitly name the class on the many-to-one mapping from my Category to Group table:

<many-to-one name="Group" class="CLEDOM.Business.Domain.Group" column="GroupId" />

That's resolved it, and my domain objects are coded against interfaces.

Thanks for the input!

I tried adding the class to the many-to-one mapping as
suggested:


<many-to-one name="Group" class="CLEDOM.Business.Domain.Group"
column="GroupId" />


And YES! That fixed my original problem!


So now it's all happy.


However the story doesn't end there. I have now got a bit further
with my tests. I have a generic broker (implementing IBroker<T> )
which I use to fetch instances from nHibernate. Standard CRUD stuff.


Before I put the interfaces on my domain objects I would create an
instance of the generic broker with something like:


broker = new Broker<Category>();


But now my domain objects are implementing interfaces I need to use
interfaces with my broker.


eg:


broker = new Broker<ICategory>();


So now when doing this and trying to get an instance from the broker I
get the following error:


"there is no persister for ICategory"


Gahhh!!!!


So I'm still a bit lost.


Max you said your domain model was coded against interfaces. Would
you be able to let me have a sample of one of your classes, it's
interface and corresponding hbm mapping?


I'm not mapping the interface in my nHibernate. Here's my mapping for
Category:


Here's my mapping file for Category:


<?xml version="1.0"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" auto-
import="true" assembly="CLEDOM.Business">
<class name="CLEDOM.Business.Domain.Category" table="CATEGORY">
<cache usage="read-only"/>
<id name="Id" type="int" column="CategoryId">
<generator class="native" />
</id>
<property name="Name" type="string" column="Name"
length="128" /
<many-to-one name="Group" class="CLEDOM.Business.Domain.Group"
column="GroupId" />
</class>
</hibernate-mapping>


So as you can see I'm not mapping the interface ICategory. Should I
be? And if so, how!?!?


Very confused.....!

Try:

Thanks, that worked!