I'm trying to create a DB Table, using an NHibernate *hbm.xml mapping file, that will have a Versioning Column for concurrency check. The Versioning column should be a nullable Integer.
Although the Database is created just fine, using the mapping file as reference, the following happen:
* The first record is inserted with a NULL value as the Version
* The update of the previously inserted records fails with a "Stale Data" exception
In other words, no matter what I do, the Version column is always NULL.
I'm somewhat new to the Concurrency Control using NHibernate, so I don't quite understand what I'm doing wrong..
If I use a Timestamp as a Version, everything works just fine. However, my requirement is to use an Integer.. Hence my problem.
This is my Mapping File:
<?xml version="1.0" encoding="utf-8"?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" default-lazy="true" auto-import="false" assembly="New1.Backend" namespace="New1.BO">
<class name="Natrio" table="`Natrios`" schema="`dbo`">
<cache usage="read-write" />
<id name="Id" column="`Id`" type="System.Int32">
<generator class="NHibernate.Id.Enhanced.TableGenerator">
<param name="increment_size">200</param>
<param name="segment_value">Natrios</param>
<param name="optimizer">pooled-lo</param>
</generator>
</id>
<version name="Version" column="`Version`" type="System.Nullable`1[[System.Int32, mscorlib]], mscorlib" generated="always" unsaved-value="0">
<column name="`Version`" not-null="false" sql-type="int" />
</version>
<property name="Attribute" column="`Attribute`" type="String" not-null="false" length="100" />
</class>
</hibernate-mapping>
Any thoughts and/or suggestions would be greatly appreciated!
Why do you need nullable version column? In any case I believe the issue is caused by unsaved-value="0" in your mapping. As default value for nullable column is null - NHibernate thinks that value is already generated and so it's never assigned. You need to set it to null - unsaved-value="null" to make it work with nullable columns. And unsaved-value="0" makes sense for not-nullable types. But better omit this attribute completely and let NHibernate to s
Another issue with generated attribute. It's about DB generation - so always means that this value is generated automatically by DB. You should remove it or specify it as generated="never".
I believe the following mapping should work for you:
<version name="Version">
<column name="`Version`" not-null="false" sql-type="int" />
</version>
Related
I've got a legacy schema with a main table and secondary table, where the secondary table connects to the main table by having the same primary key (a Secondary doesn't not necessarily exist for a given Main). I've been searching up-and-down for XML mappings that will make this work but haven't found anything that works for me.
<class name="Secondary" table="Secondary" lazy="true" dynamic-insert="true" dynamic-update="true">
<id name="mainId" type="Int32">
<column name="MAIN_ID" not-null="true" />
<generator class="foreign">
<param name="property">Main</param>
</generator>
</id>
<one-to-one class="Main" name="Main" constrained="true" />
</class>
<class name="Main" table="Main" lazy="true" dynamic-insert="true" dynamic-update="true">
<one-to-one name="Secondary" cascade="all-delete-orphan" class="Secondary" />
Also tried on the Main side, still no go. It doesn't necessarily break, but it certainly doesn't do what I expect. For example:
session.Query<Main>().Count(m => m.Secondary != null) generates
select
cast(count(*) as INT) as col_0_0_
from
MAIN main0_
where
main0_.MAIN_ID is not null
Note that it's using the MAIN_ID from the MAIN table and is ignoring Secondary altogether.
This issue is fixed in NHibernate 5.3
It's a known issue (PR with suggested fix is here).
For now as a workaround in LINQ you can call Count on some non-ID and not-nullable property:
session.Query<Main>().Count(m => m.Secondary.NotNullableProperty != null)
If such property doesn't exist (or you just want to easily find all such hacky usages in future) you can additionally map your Id column as read-only property and use it instead:
<property name="ForceJoinId" not-null="true" column="MAIN_ID" insert="false" update="false" />
session.Query<Main>().Count(m => m.Secondary.ForceJoinId != null)
I have the following nHibernate Mapping and a corresponding class. The mapping works fine.
I want the value of the field 'RfpId' to be auto inserted starting from '1'.
<?xml version="1.0" encoding="utf-8"?>
<hibernate-mapping namespace="IBeam.Core.Models" assembly="IBeam.Core" xmlns="urn:nhibernate-mapping-2.2">
<class name="Rfp" table="EST_MRFP" schema="test$tran">
<id name="Id" type="long">
<generator class="sequence" >
<param name="sequence">test$masters.global_sequence</param>
</generator>
</id>
<property name="RfpId" column="RfpId" type="String" not-null="true" />
<property name="Title" column="Title" type="String" not-null="true" />
</class>
</hibernate-mapping>
How can I do this? Right now I have created an oracle sequence 'RfpSequence'. And before every new record of type Rfp is inserted, I fetch the NEXTVAL from RfpSequence by running a query. Is there any way where nHibernate can do this for me, just like it does for the Id field.
Is the database responsible for the increment? If so try:-
<property name="RfpId" generated="always" update="false" insert="false" />
There is caveat as NH will need to perform a select straight after the insert to update the value.
Having trouble with implementing second level cache in Nhibernate. I have a class mapped as follows:
<?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="Data" namespace="Data">
<class name="Account" table="Accounts" lazy="false">
<cache region="Standard" usage="read-write" include="all"/>
<id column="ID" name="ID">
<generator class="assigned" />
</id>
<version name="VersionStamp" column="VersionStamp" type="integer" unsaved-value="0" />
<property name="Name" not-null="true" />
<property name="Type" not-null="true" />
<property name="ClientID" not-null="true" insert="false" update="false" />
<property name="DateCreated" not-null="true" type="UtcDateTime" />
<property name="LastUpdatedDate" not-null="true" type="UtcDateTime" />
<property name="IsActive" not-null="true" />
<many-to-one name="Client" class="Client" column="ClientID" not-found="exception" not-null="true" />
</class>
</hibernate-mapping>
The property "ClientID" is a foreign key into the Clients table and the Client many-to-one property uses it to look up the associated client object.
When I add a new Account, I look up the Client object from the database with a Session.Get and assign it to my Account object's Client property. Behind the scenes, this also automatically populates the ClientID property when the object is written to the database, and the ID is correctly stored in the database. When I retrieve the Account object from the database by ID using Session.Get, all the fields are populated correctly when the object is retrieved.
However, when I implement the second level cache using the settings shown above, the ClientID property is NOT populated when the Account object is retrieved using Session.Get, but the Client property is populated correctly. Is there some reason why this will not work with second level cache? Or have I done something wrong in my mapping/configuration?
For now I am just using SysCache as my caching provider, and both query and second level cache are turned on. The Client class mapping contains a corresponding one-to-many property for the Accounts.
I like the convenience of having the ClientID property on my Account class, so that I can read it without using the Client property, and it seems to work fine without caching.
Thanks for any help.
Rich
I tried to reproduce your situation locally. With your mapping (used the same as the snippet above) I was able to get incorrect behaviour only on UPDATE. In that case, the ClientID was cached, and while the Client reference was changed, the ClientID remained unchanged. In other cases caching was working as expected.
The solution is to change the mapping. The below suggested mapping is the most suitable for read-only properties like ClientID. (I am using that approach as well).
<property name="ClientID" formula="[ClientId]"
not-null="true" insert="false" update="false" />
So the trick is in the formula mapping instead of Column (the default when none is provided)
I'm trying to map a set of joined-subclass entities to a parent entity. The SQL being produced by NHibernate seems to be incorrect. Am I missing anything in my mapping? Is there another way I can approach this problem?
<class name="ResultItem" table="result">
<id name="ID">
<generator class="identity" />
</id>
<many-to-one name="Job" column="JobID"/>
<property name="Timestamp"/>
<many-to-one name="User" column="UserID"/>
<joined-subclass name="ResultItemAttachment" table="result_attachment">
<key column="ID"/>
<property name="Comment"/>
</joined-subclass>
</class>
This is the SQL being generated by NHibernate. It seems as if its getting confused between super and sub class members? The only table with JobID is the result table and not result_attachment.
SELECT attachment0_.JobID as JobID1_,
attachment0_.ID as ID1_,
attachment0_.ID as ID26_0_,
attachment0_1_.JobID as JobID26_0_,
attachment0_1_.`Timestamp` as Timestamp26_0_,
attachment0_1_.UserID as UserID26_0_,
attachment0_.`Comment` as Comment33_0_
FROM result_attachment attachment0_
inner join result attachment0_1_ on attachment0_.ID=attachment0_1_.ID
WHERE attachment0_1_.JobID=?;
Thanks in advance
I'm afraid this is currently a bug in NHibernate (in there since 2.1 :|) apperently there is a fix in the current alpha of 3.2
https://nhibernate.jira.com/browse/NH-1747
Possible work around is to manually fetch the bag at runtime. Hardly ideal, other option would be to try and get the alpha version running but running an alpha in a production environment is hardly a great idea.
I have two classes: Family and Address.
A family has a physical address and a mailing address.
The mapping file for Family looks like:
....
<id name="Id" column="Id" type="Int32" unsaved-value="0">
<generator class="native"></generator>
</id>
<many-to-one name="PhysicalAddress" class="Address" column="PhysicalAddressId" cascade="all" unique="true" />
<many-to-one name="MailingAddress" class="Address" column="MailingAddressId" cascade="all" unique="true" />
...
The mapping file for Address looks like:
...
<id name="Id" column="Id" type="Int32" unsaved-value="0">
<generator class="native"></generator>
</id>
<property name="StreetAddress1" column="StreetAddress1" />
<property name="StreetAddress2" column="StreetAddress2"/>
<property name="City" column="City" />
<property name="State" column="State" />
<property name="ZipCode" column="ZipCode" />
...
(Note that Family-PhysicalAddress and Family-MailingAddress are one-to-one relationships.)
What I would like to happen is that when I execute
aFamily.MailingAddress = null;
session.Save(aFamily);
session.Flush();
I expect NHibernate to automatically delete the mailing address record from SQL Server for me.
BUT, that doesn't happen. NHibernate does not delete the address record from SQL Server.
Is there any way I can make it work?
Thank you!
This behaviour isn't supported by NHibernate. Of course the problem is that you probably don't have access to the NHibernate session in your domain logic where the change is made.
One possible -- though admittedly not ideal solution -- is to simply run another process to clean up orphaned entities.
Here is a discussion of this scenario:
http://colinjack.blogspot.com/2008/03/nhibernate-gotchas-orphans-and-one-to.html
And a link to a ticket on the issue:
https://nhibernate.jira.com/browse/NH-1262
Unfortunately NHibernate currently does not support automatic deletions of orhphans for many-to-one (Hibernate v3 in Java does support it). It is only supported on lists (cascade="all-delete-orphan").
What you can try to do is to use component mapping. Maybe it is possible to embed many-to-one into a component.
But I think it would better to explicitly delete the related object.