Repository Pattern with Fluent Nhibernate -

hello i've implemented repository pattern fluentnhibernate have 1 concern abount exposeconfiguration when removed methods works fine when adds ,it resets tables in database. need take , give me notes implementation here unit of work class

 public class unitofwork  {      public static isession  nhibernatehelper()     {         isessionfactory _sessionfactory = fluently.configure()             .database(mssqlconfiguration.mssql2012.connectionstring(@"data source=waail-pc\computerengineer;initial catalog=tsql2012;user id=sa;password=12345678ce").showsql())             .mappings(x => x.fluentmappings.addfromassemblyof<usersmap>())            //.exposeconfiguration(cfg => new schemaexport(cfg).create(false, true)) //when removed line doesn't           //remove elements db             .buildsessionfactory();         return _sessionfactory.opensession();      }} 

and here repository pattern :

public class repository<t> :irepository<t> t :baseentity {      public repository(/*iunitofwork unitofwork*/)     {         //_unitofwork = (unitofwork)unitofwork;     }      public list<t> getall()     {         using (isession session = unitofwork.nhibernatehelper())         {             return session.query<t>().tolist();         }     }      public t getbyid(int id)     {         using (isession session = unitofwork.nhibernatehelper())         {             return session.get<t>(id);         }     }      public t insert(t entity)     {         try         {             using (isession session = unitofwork.nhibernatehelper())             {                 using (itransaction transaction = session.begintransaction())                 {                     session.save(entity);                     transaction.commit();                 }             }             return entity;         }         catch (exception)         {              throw;         }     }      public void update(t entity)     {         using (isession session = unitofwork.nhibernatehelper())         {             using (itransaction transaction = session.begintransaction())             {                 session.update(entity);                 transaction.commit();             }         }     }      public void delete(int id)     {         using (isession session = unitofwork.nhibernatehelper())         {             using (itransaction transaction = session.begintransaction())             {                 session.delete(session.load<t>(id));                 transaction.commit();             }         }     } } 

here usersservice

public class usersservice : iusersservice {     private readonly irepository<users> _repository;      #region constructor     public usersservice(irepository<users> repository)     {         _repository = repository;     }     #endregion      #region service implementation      public list<users> getlistall()     {         return _repository.getall().tolist();     }      public users getbyid(int id)     {         return _repository.getbyid(id);     }      public users insert(users user)     {         return _repository.insert(user);     }      public void update(users user)     {         _repository.update(user);     }     public void delete(int id)     {         _repository.delete(id);     }      //public int execute()     //{     //    return _repository.execute();     //}   } 

so need know why expose_configuration method causes tables reset... , secondly ,am moving in right way in implementation or not. if guys have update of improvements please tell me .. best regards.

the evil lies in details

you wrote:

... exposeconfiguration when removed methods works fine when add it, resets tables in database.

and that's pretty normal way of operations, since if nhiberate's schemaexport classes create method signature, reads:

public void create(action<string> scriptaction, bool execute) 

it's documentation states create():

run schema creation script

and parameters:

scriptaction - action called each line of generated ddl.

execute - if ddl should executed against database.

and call as:

.exposeconfiguration(cfg => new schemaexport(cfg).create(false, true)) 

your problem lies in pass true execute parameter, -as stated in documentation- execute schema creation script, might include drop , rerecration of existing database objects.

why create demons?

about second idea, see no benefit of adding layer of indirection code, , that's summon unneeded demons.

the nhibernate orm is abstraction itself, why add 1 more generic 1 around it? repository<t> calls implemented generic nhibernate methods... sort of acting proxy hide nhibernate, if that's intentional please pardon me, looks it's not.

on final note: usersservice class first violates single responsibility principle , makes life harder maintaining , testing it. second, class not more proxy call repository return values from.

let me illustrate problem:

1. client calls usersservice.getbyid(id)
2. service calls _repository.getbyid(id)
3. your generic abstraction repository calls nhibernates session.get<t>(id)

do see problem?

how easier use pattern might in case, command query separation.

where commands responsible writes, , queries reads , both suits use-cases.

you can read answers earlier queries , commands.