NHibernate.MappingException: No persister for:

Question

Now, before you say it I DID google and my hbm.xml file IS an Embedded Resource.

Here is the code I am calling:

ISession session = GetCurrentSession();
var returnObject =  session.Get<T>(Id);

Here is my mapping file for the class:

 <?xml version="1.0" encoding="utf-8" ?>
<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2">
  <class name="HQData.Objects.SubCategory, HQData" table="SubCategory" lazy="true">
    <id name="ID" column="ID" unsaved-value="0">
      <generator class="identity" />
    </id>

    <property name="Name" column="Name" />
    <property name="NumberOfBuckets" column="NumberOfBuckets"  />
    <property name="SearchCriteriaOne" column="SearchCriteriaOne" />



    <bag name="_Businesses" cascade="all">
      <key column="SubCategoryId"/>
      <one-to-many 
         class="HQData.Objects.Business, HQData"/>
    </bag>

    <bag name="_Buckets" cascade="all">
      <key column="SubCategoryId"/>
      <one-to-many
         class="HQData.Objects.Bucket, HQData"/>
    </bag>

  </class>
</hibernate-mapping>

Has anyone run to this issue before?

I swore that was it after I read it, but no dice. Here is the rest of the error and thanks for your help.

MappingException: No persister for: HQData.Objects.SubCategory]NHibernate.Impl.SessionFactoryImpl.GetEntityPersister(String entityName, Boolean throwIfNotFound) in c:\CSharp\NH2.0.0\nhibernate\src\NHibernate\Impl\SessionFactoryImpl.cs:766 NHibernate.Impl.SessionFactoryImpl.GetEntityPersister(String entityName) in c:\CSharp\NH2.0.0\nhibernate\src\NHibernate\Impl\SessionFactoryImpl.cs:752
 NHibernate.Event.Default.DefaultLoadEventListener.OnLoad(LoadEvent event, LoadType loadType) in c:\CSharp\NH2.0.0\nhibernate\src\NHibernate\Event\Default\DefaultLoadEventListener.cs:37
  NHibernate.Impl.SessionImpl.FireLoad(LoadEvent event, LoadType loadType) in c:\CSharp\NH2.0.0\nhibernate\src\NHibernate\Impl\SessionImpl.cs:2054 NHibernate.Impl.SessionImpl.Get(String entityName, Object id) in c:\CSharp\NH2.0.0\nhibernate\src\NHibernate\Impl\SessionImpl.cs:1029 NHibernate.Impl.SessionImpl.Get(Type entityClass, Object id) in c:\CSharp\NH2.0.0\nhibernate\src\NHibernate\Impl\SessionImpl.cs:1020 NHibernate.Impl.SessionImpl.Get(Object id) in c:\CSharp\NH2.0.0\nhibernate\src\NHibernate\Impl\SessionImpl.cs:985
   HQData.DataAccessUtils.NHibernateObjectHelper.LoadDataObject(Int32 Id) in C:\Development\HQChannelRepo\HQ Channel Application\HQChannel\HQData\DataAccessUtils\NHibernateObjectHelper.cs:42 HQWebsite.LocalSearch.get_subCategory() in C:\Development\HQChannelRepo\HQ Channel Application\HQChannel\HQWebsite\LocalSearch.aspx.cs:17
    HQWebsite.LocalSearch.Page_Load(Object sender, EventArgs e) in C:\Development\HQChannelRepo\HQ Channel Application\HQChannel\HQWebsite\LocalSearch.aspx.cs:27 System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +15 System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +33 System.Web.UI.Control.OnLoad(EventArgs e) +99 System.Web.UI.Control.LoadRecursive() +47 System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +1436

I had changed some code and I wasn't adding the Assembly to the config file during runtime. Thanks for your help

This has been fixed, I am not F-ing with my NHibernate setup ever again!

Answer 1

Maybe it's just a typo in your post, but does your mapping file contain an <id> element? I believe that's necessary from NHibernate's perspective.

Answer 2

Should it be name="Id"? Typos are a likely cause.

Next would be to try it out with a non-generic test to make sure you're passing in the proper type parameter.

Can you post the entire error message?

Answer 3

Sounds like you forgot to add a mapping assembly to the session factory configuration..

If you're using app.config...

.
.
    <property name="show_sql">true</property>
    <property name="query.substitutions">true 1, false 0, yes 'Y', no 'N'</property>
    <mapping assembly="Project.DomainModel"/>  <!-- Here -->
</session-factory>
.
.

Answer 4

If running tests on the repository from a seperate assembly, then make sure your Hibernate.cfg.xml is set to output always in the bin directory of said assembly. This wasn't happening for us and we got the above error in certain circumstances.

Disclaimer: This might be a slightly esoteric bit of advice, given that it's a direct result of how we structure our repository integration test assemblies (i.e. we have a symbolic link from each test assembly to a single Hibernate.xfg.xml)

Answer 5

Had a similar problem when find an object by id... All i did was to use the fully qualified name in the class name. That is Before it was :

find("Class",id)

Object so it became like this :

find("assemblyName.Class",id)

Answer 6

Something obvious, yet quite useful for someone new to NHibernate.

All XML Mapping files should be treated as Embedded Resources rather than the default Content. This option is set by editing the Build Action attribute in the file's properties.

XML files are then embedded into the assembly, and parsed at project startup during NHibernate's configuration phase.

Answer 7

Don't forget to specify mapping information in .config file

e.g.

where MyApp.Data is assembly that contains your mappings

Answer 8

I had similar problem, and I solved it as folows:

I working on MS SQL 2008, but in the NH configuration I had bad dialect: NHibernate.Dialect.MsSql2005Dialect if I correct it to: NHibernate.Dialect.MsSql2008Dialect then everything's working fine without a exception "No persister for: ..." David.

Answer 9

My issue was that I forgot to put the .hbm in the name of the mapping xml. Also make sure you make it an embedded resource!

Answer 10

I got this off of here:
http://www.mail-archive.com/[email protected]/msg03276.html
In my case the mapping class was not public i.e:
instead of :
public class UserMap:ClassMap
I just had:
class UserMap:ClassMap

Answer 11

Cant believe anyone uses this POS - decades of advances in software tools, hardware etc and we're messing around with some poorly structured config files to connect to a database and load data into an object.

You can definitely rate the intelligence and usefulness of a developer inversely by the rating they give to Hibernate.