Many-to-many cascade will not insert non-existant record

dseaver86 · **Joined:** Wed Feb 04, 2009 5:53 pm **Posts:** 5

I have a Zone <-> Sensor M;N Relation and they are mapped the following way:

Code:

<class name="Zone" table="zones">

      <id name="Num" column="zoneId" type="Int32">
         <generator class="assigned"/>
      </id>
      <property column="zoneName" type="String" name="Name" not-null="true" length="256" />
      <property column="enabled" type="Boolean" name="Enabled" not-null="true" />
      <bag name="AssignedSensors" table="SensorsInZones" lazy="false" inverse="true" >
         <key column="ZoneId"></key>
         <many-to-many class="Sensor" column="SensorId"></many-to-many>
      </bag>

   </class>

Code:

<class name="Sensor" table="sensors">

      <id name="Id" column="SensorId" type="Int32">
         <generator class="assigned"/>
      </id>
      <property column="address" type="String" name="Address" not-null="true" length="256" />
      <property column="enabled" type="Boolean" name="Enabled" not-null="true" />
      <bag name="AssignedZones" table="SensorsInZones" cascade="save-update" >
         <key column="SensorId"></key>
         <many-to-many class="Zone" column="ZoneId"></many-to-many>
      </bag>
   </class>

I have a unit test set to create a sensor and then create a zone as part of that sensor's assigned zone.

Here is the Sensor Class's members:

Code:

private string address;
   protected PropertyChangedEventHandler _propertyChanged;
  
   private IList<Zone> assignedZones;

        private bool enabled;

        private int id;

And here is the unit test code:

Code:

Repository repo;
         Sensor testSensor = new Sensor();
         using (repo = new Repository(RepositoryMode.Updatable))
         {
            WeatherInfoFetcher weatherQuery = new WeatherInfoFetcher();
            testSensor.Id = 1234;
            testSensor.Address = "123.45.67.89";
            testSensor.Enabled = true;
            
            Zone testZone = new Zone();
            testZone.Num = 1;
            testZone.Name = "Front Yard";
            testZone.Enabled = true;
            testSensor.AssignedZones.Add(testZone);
            repo.SensorDAO.Insert(testSensor);
}

Here are my errors:

Code:

WeatherInfo.UnitTest.DALFixture.SensorDAOTest:
NHibernate.StaleStateException : Unexpected row count: 0; expected: 1

Code:

NHibernate: INSERT INTO sensors (address, enabled, SensorId) VALUES (@p0, @p1, @p2); @p0 = '123.45.67.89', @p1 = 'True', @p2 = '1234'
NHibernate: UPDATE zones SET zoneName = @p0, enabled = @p1 WHERE zoneId = @p2; @p0 = 'Front Yard', @p1 = 'True', @p2 = '1'

Code:

17:00:33,952 ERROR [TestRunnerThread] AbstractFlushingEventListener [(null)]- Could not synchronize database state with session
NHibernate.StaleStateException: Unexpected row count: 0; expected: 1

   at NHibernate.AdoNet.Expectations.BasicExpectation.VerifyOutcomeNonBatched(Int32 rowCount, IDbCommand statement)

   at NHibernate.AdoNet.NonBatchingBatcher.AddToBatch(IExpectation expectation)

   at NHibernate.Persister.Entity.AbstractEntityPersister.Update(Object id, Object[] fields, Object[] oldFields, Object rowId, Boolean[] includeProperty, Int32 j, Object oldVersion, Object obj, SqlCommandInfo sql, ISessionImplementor session)

   at NHibernate.Persister.Entity.AbstractEntityPersister.UpdateOrInsert(Object id, Object[] fields, Object[] oldFields, Object rowId, Boolean[] includeProperty, Int32 j, Object oldVersion, Object obj, SqlCommandInfo sql, ISessionImplementor session)

   at NHibernate.Persister.Entity.AbstractEntityPersister.Update(Object id, Object[] fields, Int32[] dirtyFields, Boolean hasDirtyCollection, Object[] oldFields, Object oldVersion, Object obj, Object rowId, ISessionImplementor session)

   at NHibernate.Action.EntityUpdateAction.Execute()

   at NHibernate.Engine.ActionQueue.Execute(IExecutable executable)

   at NHibernate.Engine.ActionQueue.ExecuteActions(IList list)

   at NHibernate.Engine.ActionQueue.ExecuteActions()

   at NHibernate.Event.Default.AbstractFlushingEventListener.PerformExecutions(IEventSource session)

Any idea what the problem is??

dseaver86 · **Joined:** Wed Feb 04, 2009 5:53 pm **Posts:** 5

And I have a related question: Will there be a cyclic retrieval when retrieving either class? Because Zones contain Sensors contain Sensors...etc. How does NHibernate handle that gracefully

wolli · **Posted:** Thu Feb 05, 2009 3:59 am

To your first problem: That's caused by "assigned" ids. have a look here:

Code:

http://nhforge.org/doc/nh/en/index.html#example-parentchild-update

Cascaded update needs some additional hints in that case. E.g. a timestamp or a version column. Without that hibernate assumes it has to update that record and therefore is expecting one record and finds 0.

To your second problem: It depends a bit on how you define the fetching in the mapping and the query. And since everything happens in the same session, hibernate will only instantiate every object once, even if its retrieved multiple times.

The best thing to understand what's happening is to enable sql output with "show_sql=true" in the config and play with the mapping and the query.

dseaver86 · **Joined:** Wed Feb 04, 2009 5:53 pm **Posts:** 5

So I added native id's to all my classes which are mapped to an autoincrementing column and I got the following error:

Code:

WeatherInfo.UnitTest.DALFixture.SensorDAOTest:
NHibernate.AssertionFailure : null id in WeatherInfo.Domain.Zone entry (don't flush the Session after an exception occurs)

Here are the new mappings

Code:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="WeatherInfo.Domain" namespace="WeatherInfo.Domain">
   <class name="Sensor" table="sensors">

      <id name="Id" column="Id" type="Int32">
         <generator class="assigned"/>
      </id>
      <property column="number" type="Int32" name="Number" not-null="true"/>
      <property column="address" type="String" name="Address" not-null="true" length="256" />
      <property column="enabled" type="Boolean" name="Enabled" not-null="true" />
      <bag name="AssignedZones" table="SensorZoneMap" cascade="save-update" >
         <key column="SensorId"></key>
         <many-to-many class="Zone" column="ZoneId"></many-to-many>
      </bag>
   </class>
</hibernate-mapping>

Code:

<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="WeatherInfo.Domain" namespace="WeatherInfo.Domain">
   <class name="Zone" table="zones">
      <id name="Id" column="Id" type="Int32">
         <generator class="native"/>
      </id>
      <property column="Number" type="Int32" name="Num" not-null="true"  />
      <property column="Name" type="String" name="Name" not-null="true" length="256" />
      <property column="enabled" type="Boolean" name="Enabled" not-null="true" />
      <bag name="AssignedSensors" table="SensorZoneMap" lazy="false" inverse="true" >
         <key column="ZoneId"></key>
         <many-to-many class="Sensor" column="SensorId"></many-to-many>
      </bag>
   </class>
</hibernate-mapping>

Any ideas what the problem is here?

Thanks!

wolli · **Posted:** Fri Feb 06, 2009 12:50 pm

Quote:

WeatherInfo.UnitTest.DALFixture.SensorDAOTest:
NHibernate.AssertionFailure : null id in WeatherInfo.Domain.Zone entry (don't flush the Session after an exception occurs)

After an exception, the session is invalid and can't be used any more. You have to close it and use a new one. But I can't tell you why you get an exception.

Is it possible that you still have this line in your code ?

testZone.Num = 1;

You mustn't manually assign an id to an automatically generated one.

dseaver86 · **Joined:** Wed Feb 04, 2009 5:53 pm **Posts:** 5

Duh, I still had the sensor having an Id assigned! Thanks for picking up on that!!