Type conversion exception while using NHibernate

Question

I've got the following persistence class with the corresponding XML mapping file:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace DataAccessLayer.Poco
{
    public class User
    {
        private int id;
        private int positionId;
        private int companyId;
        private int roleId;
        private int languageId;
        private string firstname;
        private string firstnameUpperCase;
        private string lastname;
        private string initials;
        private string pseudonyms;
        private string mail;
        private string phone;
        private string mobile;
        private bool managementFlag;
        private bool activityFlag;
        private string information;
        private string image;
        private string path;

        public User()
        {

        }

        public virtual int Id
        {
            get { return id; }
            set { id = value; Console.WriteLine("setter Id");}
        }

        public virtual int PositionId
        {
            get { return positionId; }
            set { positionId = value; Console.WriteLine("setter PositionId"); }
        }

        public virtual int CompanyId
        {
            get { return companyId; }
            set { companyId = value; Console.WriteLine("setter CompanyId"); }
        }

        public virtual int RoleId
        {
            get { return roleId; }
            set { roleId = value; Console.WriteLine("setter RoleId"); }
        }

        public virtual int LanguageId
        {
            get { return languageId; }
            set { languageId = value; Console.WriteLine("setter LanguageId"); }
        }

        public virtual string Firstname
        {
            get { return firstname; }
            set { firstname = value; Console.WriteLine("setter Firstname"); }
        }

        public virtual string FirstnameUpperCase
        {
            get { return firstnameUpperCase; }
            set { firstnameUpperCase = value; Console.WriteLine("setter FirstnameUpperCase"); }
        }

        public virtual string Lastname
        {
            get { return lastname; }
            set { lastname = value; Console.WriteLine("setter Lastname"); }
        }

        public virtual string Initials
        {
            get { return initials; }
            set { initials = value; Console.WriteLine("setter Initials"); }
        }

        public virtual string Pseudonyms
        {
            get { return pseudonyms; }
            set { pseudonyms = value; Console.WriteLine("setter Pseudonyms"); }
        }

        public virtual string Mail
        {
            get { return mail; }
            set { mail = value; Console.WriteLine("setter Mail"); }
        }

        public virtual string Phone
        {
            get { return phone; }
            set { phone = value; Console.WriteLine("setter Phone"); }
        }

        public virtual string Mobile
        {
            get { return mobile; }
            set { mobile = value; Console.WriteLine("setter Mobile"); }
        }

        public virtual bool ManagementFlag
        {
            get { return managementFlag; }
            set { managementFlag = value; Console.WriteLine("setter ManagementFlag"); }
        }

        public virtual bool ActivityFlag
        {
            get { return activityFlag; }
            set { activityFlag = value; Console.WriteLine("setter activityFlag"); }
        }

        public virtual string Information
        {
            get { return information; }
            set { information = value; Console.WriteLine("setter information"); }
        }

        public virtual string Image
        {
            get { return image; }
            set { image = value; Console.WriteLine("setter image"); }
        }

        public virtual string Path
        {
            get { return path; }
            set { path = value; Console.WriteLine("setter path"); }
        }
    }
}

And the XML file:

<many-to-one name="CompanyId"
             unique="true"
             class="Company">
  <column name="companyId" />
</many-to-one>

<many-to-one name="PositionId"
         unique="true"
         class="Position">
  <column name="positionId" />
</many-to-one>

<many-to-one name="RoleId"
         unique="true"
         class="Role">
  <column name="roleId" />
</many-to-one>

<many-to-one name="LanguageId"
         unique="true"
         class="Language">
  <column name="languageId" />
</many-to-one>

<property name="Firstname" column="firstname" type="String" />
<property name="FirstnameUpperCase" column="firstnameUpperCase" type="String" />
<property name="Lastname" column="lastname" type="String" />
<property name="Initials" column="initials" type="String" />
<property name="Pseudonyms" column="pseudonyms" type="String" />
<property name="Mail" column="mail" type="String" />
<property name="Phone" column="phone" type="String" />
<property name="Mobile" column="mobile" type="String" />
<property name="ManagementFlag" column="managementFlag" type="Boolean" />
<property name="ActivityFlag" column="activityFlag" type="Boolean" />
<property name="Information" column="information" type="String" />
<property name="Image" column="image" type="String" />
<property name="Path" column="path" type="String" />

Each time, I want to read a User object from the MySQL database, I get the following Exception:

NHibernate.PropertyAccessException: Invalid Cast (check your mapping for property type mismatches); setter of DataAccessLayer.Poco.User ---> System.InvalidCastException: Die angegebene Umwandlung ist ungültig.
   bei (Object , Object[] , SetterCallback )
   bei NHibernate.Bytecode.Lightweight.AccessOptimizer.SetPropertyValues(Object target, Object[] values)
   bei NHibernate.Tuple.Entity.PocoEntityTuplizer.SetPropertyValuesWithOptimizer(Object entity, Object[] values)
   --- Ende der internen Ausnahmestapelüberwachung ---
   bei NHibernate.Tuple.Entity.PocoEntityTuplizer.SetPropertyValuesWithOptimizer(Object entity, Object[] values)
   bei NHibernate.Tuple.Entity.PocoEntityTuplizer.SetPropertyValues(Object entity, Object[] values)
   bei NHibernate.Persister.Entity.AbstractEntityPersister.SetPropertyValues(Object obj, Object[] values, EntityMode entityMode)
   bei NHibernate.Engine.TwoPhaseLoad.InitializeEntity(Object entity, Boolean readOnly, ISessionImplementor session, PreLoadEvent preLoadEvent, PostLoadEvent postLoadEvent)
   bei NHibernate.Loader.Loader.InitializeEntitiesAndCollections(IList hydratedObjects, Object resultSetId, ISessionImplementor session, Boolean readOnly)
   bei NHibernate.Loader.Loader.DoQuery(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies, IResultTransformer forcedResultTransformer)
   bei NHibernate.Loader.Loader.DoQueryAndInitializeNonLazyCollections(ISessionImplementor session, QueryParameters queryParameters, Boolean returnProxies, IResultTransformer forcedResultTransformer)
   bei NHibernate.Loader.Loader.DoList(ISessionImplementor session, QueryParameters queryParameters, IResultTransformer forcedResultTransformer)
   bei NHibernate.Loader.Loader.ListIgnoreQueryCache(ISessionImplementor session, QueryParameters queryParameters)
   bei NHibernate.Loader.Loader.List(ISessionImplementor'test.exe' (CLR v4.0.30319: test.exe):
 session, QueryParameters queryParameters, ISet`1 querySpaces, IType[] resultTypes)
   bei NHibernate.Loader.Hql.QueryLoader.List(ISessionImplementor session, QueryParameters queryParameters)
   bei NHibernate.Hql.Ast.ANTLR.QueryTranslatorImpl.List(ISessionImplementor session, QueryParameters queryParameters)
   bei NHibernate.Engine.Query.HQLQueryPlan.PerformList(QueryParameters queryParameters, ISessionImplementor session, IList results)
   bei NHibernate.Impl.SessionImpl.List(IQueryExpression queryExpression, QueryParameters queryParameters, IList results)
   bei NHibernate.Impl.AbstractSessionImpl.List(IQueryExpression queryExpression, QueryParameters parameters)
   bei NHibernate.Impl.AbstractQueryImpl2.List()
   bei DataAccessLayer.Impl.UserDao.get(Int32 entityId)

Oskar Berggren · Accepted Answer · 2016-08-03 15:33:35Z

2

The most obvious thing that stands out is that you need to review the many-to-one element again. The many-to-one element is used like this:

public class Foo {
    public Bar RelatedBar {get; set;}
}

public class Bar {
    public int BarId {get; set;}
}

Foo can then be mapped like this:

<many-to-one name="RelatedBar" class="Bar"><!-- class attribute is optional -->
    <column name="RelatedBarId" />
</many-to-one>

If you really want to have something like RelatedBarId in the Foo class, you would need to map it using the property-element, and NHibernate would then not know about the relationship.

answered Aug 3, 2016 at 15:33

Oskar Berggren

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