How to implement correctly IUserType?
c#, ncommon, nhibernate, nhibernate-mapping
Solution
Have a look at how Ritesh Rao has done this in his NCommon framework:
The MoneyUserType implements a base class called CompositeUserTypeBase
There's more detail in the comments but to summarize:
- DeepCopy - should return a deep copy of the persistent state, stopping at entities and at collections
- Disassemble - transforms the object into its 'cacheable' representation (i.e. associations must be cached as identifier values)
- Assemble - reconstructs an object from the cacheable representation
It's explained in a lot more detail here
Problem
I need to create a custom type for NHibernate by writing a new mapper class that implements `IUserType`. While it is relatively straightforward to override most of the methods and properties, I get some difficulties to understand how to deal correctly with the following members: - `object Assemble(object cached, object owner);` - `object DeepCopy(object value);` - `object Disassemble(object value);` - `object Replace(object original, object target, object owner);` I do not understand what is exactly their purpose; and more important, how to properly implement them. Most of the examples I have seen just return the raw input parameter. ``` public object DeepCopy(object value) { return value; } public object Replace(object original, object target, object owner) { return original; } public object Assemble(object cached, object owner) { return cached; } public object Disassemble(object value) { return value; } ``` How to implement those methods correctly in a real case or more complex scenario?