Creating Database class Library using NHibernate

Question

I am writing an Class Library as DataModel. DataModel capable of handling all the Database related task. I am using NHibernate and Fluent NHibernate for the same.

Now the question arises are as follows :

1. Should we expose the Entity (POCO Class).
2. Is it good to have a Entity with internal protected property and property exposed as a interface.
3. Entity created for mapping can be a Model for WPF MVVM.
4. Or should we directly bind entity ?.
5. There is no control if Library returns a List of entity as API return. So anybody can do add or delete in list. How should I keep control on it. Should I create proxy derived from IList which will keep track of it.
6. Is it right to throw Exception occurring in an API or should I return null?.
7. Is it good keep logging in the Library ?.

Answer 1

Should we expose the Entity (POCO Class).

Yes, Creating wrapper class makes more effort.

Is it good to have a Entity with internal protected property and property exposed as a interface.

Yes, Setter and non-exposed properties are control.

Entity created for mapping can be a Model for WPF MVVM.

For primitive type can be, but reference can be exposed by interface.

Or should we directly bind entity ?.

If Model is created rather directly use of POCO object. It is much more flexible for refresh cases. User can not change property of POCO object if cancel operation is there.

There is no control if Library returns a List of entity as API return. So anybody can do add or delete in list. How should I keep control on it. Should I create proxy derived from IList which will keep track of it.

IEnumerable is used to exposed collection by interface.

Is it right to throw Exception occurring in an API or should I return null?.

Exception is much more better to make know to user about error. but wrap the exception in user readable rather returning NHibernate exception.

Is it good keep logging in the Library

Logging is very good feature to know about issue.