NHibernate.MappingException: No persister for: XYZ


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?

Here is the full error message:

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

Update, here's what the solution for my scenario was: I had changed some code and I wasn't adding the Assembly to the config file during runtime.

1
130
9/22/2013 9:04:03 PM

Accepted Answer

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>
.
.
98
9/12/2008 12:20:28 AM

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.


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