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 lt T gt  Id     Here is my mapping file for the class    lt  xml version  1 0  encoding  utf-8    gt   lt hibernate-mapping xmlns  urn nhibernate-mapping-2 2  gt     lt class name  HQData Objects SubCategory  HQData  table  SubCategory  lazy  true  gt       lt id name  ID  column  ID  unsaved-value  0  gt         lt generator class  identity    gt       lt  id gt        lt property name  Name  column  Name    gt       lt property name  NumberOfBuckets  column  NumberOfBuckets     gt       lt property name  SearchCriteriaOne  column  SearchCriteriaOne    gt        lt bag name   Businesses  cascade  all  gt         lt key column  SubCategoryId   gt         lt one-to-many           class  HQData Objects Business  HQData   gt       lt  bag gt        lt bag name   Buckets  cascade  all  gt         lt key column  SubCategoryId   gt         lt one-to-many          class  HQData Objects Bucket  HQData   gt       lt  bag gt      lt  class gt   lt  hibernate-mapping gt    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

User · 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>
.
.

User · Answer

I have a similar problem but all mentioned requirements are met  In my case I try to save some entity class  Type of OBJEKTE  back to the DB  Other places do work but only in this case it fails and raises this exception   My solution  HACK  was to re-map the objet of type OBJEKTE again and store it then  Suddenly it works  But don t ask why                OBJEKTE t    mapper Map lt OBJEKTE gt  inparam               OBJEKTE res   await  objRepo UpdateAsync t     If inparam would go straight to UpdateAsync   it cannot find a matching persistor   It could be explained by the way NH does this  It derives a proxy from your mapping class and implements the properties with dirty handling included  See this   t GetType    Name    OBJEKTE  FullName    MyComp Persistence OBJEKTE    inparam GetType    Name    OBJEKTEProxyForFieldInterceptor  FullName    OBJEKTEProxyForFieldInterceptor     The fun thing though is that the source of inparam is in fact the NH repository itself  Anyways  I stay with this reassign hack for the next time being

User · Answer

I had the same problem because I was adding the wrong assembly in Configuration AddAssembly   method

User · Answer

I got this off of here   In my case the mapping class was not public  In other words  instead of   public class UserMap   ClassMap lt user gt      note the public    I just had   class UserMap   ClassMap lt user gt

User · Answer

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

User · Answer

Spending about 4 hours on googling and stackoverflowing  trying all of stuff around there  i ve found my error   My mapping file was called  nbm xml instead of  hbm xml  That was insane

User · Answer

I my case I fetched an entity without await  var company    unitOfWork Session GetAsync lt Company gt  id    and then I tried to delete it  await  unitOfWork Session DeleteAsync company    I could not decipher the error message that I m deleting a Task lt Company gt  instead of Company  MappingException  No persister for  System Runtime CompilerServices AsyncTaskMethodBuilder 1 AsyncStateMachineBox 1  SmartGuide Core Domain Users Company  SmartGuide Core  Version 2 0 0 0  Culture neutral  PublicKeyToken null   NHibernate Impl SessionImpl d  54 1  SmartGuide Core Domain Users Company  SmartGuide Core  Version 2 0 0 0  Culture neutral  PublicKeyToken null    NHibernate  Version 5 3 0 0  Culture neutral  PublicKeyToken aa95f207798dfdb4

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

This error occurs because of invalid mapping configuration  You should check where you set  Mappings for your session factory  Basically search for   Mappings   in your project and make sure you specified correct entity class in below line    Mappings m   gt  m FluentMappings AddFromAssemblyOf lt YourEntityClassName gt

User · Answer

Make sure you have called the CreateCriteria typeof DomainObjectType   method on Session for the domain object which you intent to fetch from DB

User · Answer

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

User · Answer

Don t forget to specify mapping information in  config file  e g    where MyApp Data is assembly that contains your mappings

User · Answer

I was also adding the wrong assembly during initialization  The class I m persisting is in assembly  1  and my  hbm xml file is embedded in assembly  2  I changed cfg AddAssembly     to add assembly  2  instead of assembly  1  and everything worked  Thanks

User · Answer

To add to Amol s answer  don t make the mistake of specifying the Interface class type   Make sure you specify the implementation class    Ie  don t use IDomainObjectType   Not that I made this mistake

[c#] NHibernate.MappingException: No persister for: XYZ

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