I'm trying to cascade class1 with a one-to-many relationship to class2 which, in turn, has a many-to-one relationship with class3.

The problem is that class2 has a composite key containing the keys from class1 and class3 and the key from class3 is auto-generated.

This is the error I get:
#23000Cannot add or update a child row: a foreign key constraint fails (`supremacy/gameuser`, CONSTRAINT `FK_gameuser_game` FOREIGN KEY (`gameid`) REFERENCES `game` (`gameid`))

here are my mapping files:

<class name="Class1, DataAccess" table="1">

<id name="ID1" column="userid" type="Int32">
<generator class="identity" />
</id>

<bag name="class2list" inverse="true" cascade="all" table="tbl1tbl3">
<key column="id1"/>
<one-to-many class="class1class3, DataAccess"/>
</bag>
</class>

<class name="class1class3, DataAccess" table="tbl1tbl3">

<composite-id unsaved-value="any">
<key-property name="ID1" column="id1" type="Int32"/>
<key-property name="ID3" column="id3" type="Int32"/>
</composite-id>

<many-to-one name="Class3Obj" class="Class3, DataAccess" cascade="all" column="id3" insert="false" update="false" />
</class>

<class name="Class3, DataAccess" table="tbl3">
<id name="ID3" column="id3" type="Int32" unsaved-value="-1">
<generator class="identity" />
</id>
</class>

And here is the code that I'm using to try to do this:

Class3 new3 = new Class3();

Class13 new13 = new Class13();
new13.Class3obj = new3;
Current1.class21list.Add(new13);

I am pretty sure the fields used in the composite key have to be nullable. NH first tried to delete the child objects and then recreates them. even the ones you haven't changed. check your log files for NH to see exactly what is going on. you can also search here on composite keys for more info.

That didn't work. the problem as I see it is that new3 needs to be saved before new13 but that isn't happening. Also, I forgot to include that I'm doing this in a transaction. Does it matter if I try to do this using Session.Save() or transaction.Commit()?

I just noticed that you set the insert/update in the many-to-one from class1class3 to class3 as false. From thedocs:



In this instance you would manually have to save the class3 object first. Why are you setting those values to false?

Because when I set them to true it says that for a many-to-one class you have to set them to false

Okay, I'm reaching here because I've not heard or seen that before. I have many m-1 relatinships with setting those values, but not inside composite-id classes. However, going over the HiA book, it does state specifically:



So you might want to add that field to your class. Also, you need to be sure you're implementing Equals() and GetHashCode() which I'm sure you are.

So is that essentially saying I need to make a unique key for that table (such as a version or timestamp) and then just make the other fields foreign keys?

When I change those to "true" I get this error:

Repated column in mapping for class Class13 should be mapped with insert="false" update="false": ID3

well actually, if you have the option, in my opinion, you should never use natural (composite keys). So, yes, if you can, create a surrogate key and then PK/FK the two opbects you are trying to relate:



-devon