Question

I am having a problem in Fluent NHibernate example utilizing the Many-to-Many relationships. I tried to find out examples on a similar case, and I found tons, but I’m still having the same problem.

When running the test project, the following exception is thrown:

NHibernate.PropertyAccessException: Exception occurred getter of project.Entities.User.UserName —> System.Reflection.TargetException: Object does not
match target type.

This is an image of the tables:

and the code

 public UsersMap()
    {

        this.Table("Users");
        Id(x => x.UserName).Column("Username").GeneratedBy.Assigned();

        Map(x => x.FirstName);
        Map(x => x.LastName);
        Map(x => x.Password);
        Map(x =>x.EMail);
        Map(x => x.Title);
        Map(x => x.Division);


        HasManyToMany<User>(x => x.Roles)
            .Table("UserInRoles").ParentKeyColumn("Username")
            .ChildKeyColumn("Usernamepk")
           .Cascade.SaveUpdate().LazyLoad();


    }

  public RolesMap()
    {
        this.Table("Roles");
        Id(x => x.ID).GeneratedBy.Assigned().Column("ID");
        Map(x => x.RoleName).Length(50);

        HasManyToMany<User>(x => x.Users)
            .Table("UserInRoles").ParentKeyColumn("ID")
            .ChildKeyColumn("RoleIdpk").Cascade.SaveUpdate().LazyLoad();

    }

here is the code, most examples on the web and the Fluent Nhibernate mappings page are written in the same way, so any ideas ?

Answer 1

Regarding to code I am using in my project I would define your manyTomany relations this way:

 public UsersMap()
    {
...
            HasManyToMany(x => x.Roles)
                .WithTableName("UserInRoles")
                .WithParentKeyColumn("Usernamepk")
                .WithChildKeyColumn("RoleIdpk");
    }

  public RolesMap()
    {
...
            HasManyToMany(x => x.Users)
                .WithTableName("UserInRoles")
                .WithParentKeyColumn("RoleIdpk")
                .WithChildKeyColumn("Usernamepk");

    }

Such a definitions works for me.
Check this first then decorate with LazyLoading and some other properties.