That's because composite-id is the only way to make many-to-one association
on your ID. There's no other way.
You are allowed to have one or more properties as your composite-id. So one
property is completely a valid mapping.
What's invalid here is apparently the way I retrieve the instance, it had a
semantic error. The correct way to get the object is:
session.Get<UserProfile>(new UserProfile{Id = user});
Unfortunately the following code doesnt work either (it fails during the
logging attempt):
session.Get<UserProfile>(new {Id = user});
You have to construct an actual fullblown UserProfile entity to represent
your ID solely for querying purpose.
Similarly, if you have 2 properties under your composite-id, you can't do
this either:
session.Get<UserProfile>(new {Id1 = a, id2 = b});
That will throw an error during logging too. You always have to instantiate
your entity.
I havent' had a chance to investigate if this error is just a logging
problem during the debug-mode, and whether it will actually work just fine
in the production-mode (non-debug).
Cheers, and so yes I have managed to get that working by instantiating a
dummy instance of my entity for every call to GetById, which is not optimal
but it works.
On Fri, Jan 7, 2011 at 10:24 PM, José F. Romaniello
<[email protected]>wrote:
> I didn't go further on reading this message after i saw the mapping.
> Composite-id means composite-id, multiples columns are part of the PK and
> you have *only one.*
> The weird part of this, is that I'm sure you have read somewhere how bad
> are composite ids, however you have a pretty common case of one-to-one by
> primary key, that is very well supported by nhbiernate and you are trying to
> map it as a composite id.
>
> Read the section of one-to-one mapping,
> http://nhforge.org/doc/nh/en/index.html#mapping-declaration-onetoone
> you need to use <generator class="foreign" on UserProfile id as described
> there.
>
>
> 2011/1/7 Hendry Luk <[email protected]>
>
>> Hello,
>> How does one go about reporting a new bug in NH jira?
>> I encountered the following issue.
>>
>> <?xml version="1.0" encoding="utf-8" ?>
>> <hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
>> assembly="MyDomain"
>> namespace="MyDomain.Model">
>>
>> <class name="UserProfile">
>>
>> <composite-id >
>> <key-many-to-one name="Id" column="UserId" class="User" />
>> </composite-id>
>>
>> </class>
>> </hibernate-mapping>
>>
>> session.Get<UserProfile>(user);
>>
>> During debug-mode, that will throw an InvalidCastException from
>> ComponentType.ToLoggableString() method. It's fine during non debug-mode.
>>
>> The cause of that error, as I tracked down, is due to an attempt to get a
>> string description from entity's ID (User object) by calling
>> ComponentType.ToLoggableString().
>> Since we specify neither the property-name nor the class attribute in the
>> <composite-id> element, nhibernate mistakenly uses EmbeddedComponentType of
>> UserProfile class (instead of User class) in its attempt to GuessEntityMode
>> of our User object. This will obviously fail, and the logger decides to
>> throw exception on this situation (it should at least resort to other
>> method.. afterall its sole purpose is just to print the string
>> representation of the Id object).
>>
>> There's no appropriate workaround that I can think of that wouldn't
>> compromise what I want to achieve. I can't specify class name in the
>> <composite-id> element because NH will (inappropriately) complaint that this
>> entity doesnt have an ID (because I set the class without the
>> property-name). And obviously I can't specify the property-name because I
>> want to have "many-to-one"ed complex type as my ID.
>>
>> I strongly believe this is a bug that needs to be fixed, and make the
>> logging less intrusive. This issue has been raiseed in java's Hibernate
>> before (
>> http://opensource.atlassian.com/projects/hibernate/browse/HHH-3148)
>>
>> Some ways to fix this that I can think of: not relying on tuplizer for
>> logging at all, or may be resort to other way to produce the logging string
>> in situations when no tuplizer is found (rather than throwing an exception).
>>
>> Cheers
>>
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