Hello,

I was trying to make one-to-many and many-to-many relation using NHibernate. I have Customer item with collection of Invoices (one-to-many) and Invoice with its Products (many-to-many). Ther is no problem with selecting all data from database(MSSQL), but when I`m trying to save Customer with Invoice with its Products I`m getting ADOException: "Cannot update identity column".

I am totally new to NHibernate and stuck on this problem :(

Can anybody help?
Maciek

Mapping files looks like this:
(Customer.hbm.xml)
<?xml version="1.0"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
namespace="InvoiceNH"
assembly="InvoiceNH">
<!-- Mappings for class 'Customer' -->
<class name="Customer" table="Customer" lazy="false">
<!-- Identity mapping -->
<id name="Id">
<column name="Id" />
<generator class="native" />
</id>

<component name="Address">
<property name="Street" />
<property name="City" />
<property name="PostalCode" />
</component>
<!-- One-to-many mapping: Invoice -->
<bag name="Invoices" cascade="all-delete-orphan" lazy="false">
<key column="Id" />
<one-to-many class="Invoice" />
</bag>

<property name="Name" />
<property name="Telephon" />
</class>
</hibernate-mapping>


(Invoice.hbm.xml)
<?xml version="1.0"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
namespace="InvoiceNH"
assembly="InvoiceNH">

<!-- Mappings for class 'Invoice' -->
<class name="Invoice" table="Invoice" lazy="false">
<!-- Identity mapping -->
<id name="Id">
<column name="Id" />
<generator class="native" />
</id>
<!-- Many-to-one mapping: Customer -->
<many-to-one name="Customer"
class="Customer"
column="CustomerId"
cascade="all" />
<!-- Many-to-many mapping: InvoiceProducts -->
<bag name="Products" table="InvoiceProducts" cascade="none" lazy="false">
<key column ="InvoiceId" />
<many-to-many class="Product" column="ProductId" />
</bag>
<!-- Simple mappings -->
<property name="Date" />
<property name="InvoiceNumber" />
</class>
</hibernate-mapping>

Exception code
NHibernate.ADOException was unhandled
Message="could not insert collection: [InvoiceNH.Customer.Invoices#14]"
Source="NHibernate"
StackTrace:
at NHibernate.Persister.Collection.AbstractCollectionPersister.Recreate(IPersistentCollection collection, Object id, ISessionImplementor session)
at NHibernate.Impl.ScheduledCollectionRecreate.Execute()
at NHibernate.Impl.SessionImpl.Execute(IExecutable executable)
at NHibernate.Impl.SessionImpl.ExecuteAll(IList list)
at NHibernate.Impl.SessionImpl.Execute()
at NHibernate.Impl.SessionImpl.Flush()
at NHibernate.Transaction.AdoTransaction.Commit()
at InvoiceNH.PersistenceManager.Save[T](T item) in C:\SVN\InvoiceNH\InvoiceNH\DataAccessLayer\PersistenceManager.cs:line 80
at InvoiceNH.Controller.SaveBusinessObjects() in C:\SVN\InvoiceNH\InvoiceNH\DomainLayer\Controller.cs:line 44
at InvoiceNH.Program.Main(String[] args) in C:\SVN\InvoiceNH\InvoiceNH\PresentationLayer\Program.cs:line 15
at System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)
at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)
at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()
at System.Threading.ThreadHelper.ThreadStart_Context(Object state)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException: System.Data.SqlClient.SqlException
Message="Cannot update identity column 'Id'."
Source=".Net SqlClient Data Provider"
ErrorCode=-2146232060
Class=16
LineNumber=1
Number=8102
Procedure=""
Server="localhost"
State=1
(...)

SQL queries get from Profiler:

exec sp_executesql N'INSERT INTO Customer (Street, City, PostalCode, Name, Telephon) VALUES (@p0, @p1, @p2, @p3, @p4); select SCOPE_IDENTITY()',N'@p0 nvarchar(15),@p1 nvarchar(8),@p2 nvarchar(6),@p3 nvarchar(10),@p4 nvarchar(14)',@p0=N'Kaprio 123/4',@p1=N'Rzeszow',@p2=N'03-982',@p3=N'Hotel',@p4=N'123 456-66-22'


exec sp_executesql N'INSERT INTO Invoice (CustomerId, Date, InvoiceNumber) VALUES (@p0, @p1, @p2); select SCOPE_IDENTITY()',N'@p0 int,@p1 datetime,@p2 nvarchar(13)',@p0=12,@p1='2009-09-03 00:19:44:000',@p2=N'FV/2009/02/15'


exec sp_executesql N'UPDATE Invoice SET Id = @p0 WHERE Id = @p1',N'@p0 int,@p1 int',@p0=12,@p1=102 (this update generate exception I suppose)

I found problem. Customer.hbm.xml shoud look like this:

<?xml version="1.0"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2"
namespace="InvoiceNH"
assembly="InvoiceNH">
<!-- Mappings for class 'Customer' -->
<class name="Customer" table="Customer" lazy="false">
<!-- Identity mapping -->
<id name="Id">
<column name="Id" />
<generator class="native" />
</id>

<component name="Address">
<property name="Street" />
<property name="City" />
<property name="PostalCode" />
</component>
<!-- One-to-many mapping: Invoice -->
<bag name="Invoices" cascade="all-delete-orphan" lazy="false">
<key column="CustomerId" />
<one-to-many class="Invoice" />
</bag>

Best wishes!
Maciek

Thanks for posting the solution!!! Had the same problem.