entity framework - Autofac using Constructor -

i use unit of work pattern entityframework code first. want use autofac register unitofwork, repositories , dbcontext.

this unitofwork code:

public class unitofwork : iunitofwork {     private readonly dbcontext _context;      public unitofwork(dbcontext context)     {         _context = context;          contact = new contractrepository(context);     }      public void dispose()     {         _context.dispose();         gc.suppressfinalize(_context);     }      public icontactrepository contact { get; private set; }      public int complete()     {         return _context.savechanges();     } } 

and repository:

public class repository<entity> : irepository<entity> entity : class {     protected readonly dbcontext _notebookcontext;     public repository(dbcontext notebookcontext)     {         _notebookcontext = notebookcontext;     }     public void add(entity entity)     {         _notebookcontext.set<entity>().add(entity);     } } 

and 1 of repositories:

public  class contractrepository: repository<contact>,icontactrepository  {     public contractrepository(dbcontext notebookcontext) : base(notebookcontext)     {      }      public dbcontext notebookcontext     {                 {             return _notebookcontext;         }     } } 

and db context class:

public class notebookcontext:dbcontext {     public notebookcontext(string connectionstring):base(connectionstring)     {      }     protected override void onmodelcreating(dbmodelbuilder modelbuilder)     {         modelbuilder.configurations.add(new contactconfig());         modelbuilder.configurations.add(new phoneconfig());         modelbuilder.configurations.add(new phonetypeconfig());         modelbuilder.configurations.add(new groupconfig());         base.onmodelcreating(modelbuilder);     }     public dbset<contact> contacts { get; set; }     public dbset<phone> phones { get; set; }      public dbset<group> groups { get; set; }      public dbset<phonetype> phonetypes { get; set; } } 

now want register unitofwork constructor (a constructor this: )

var uow = new unitofwork(new notebookdbcontext("connectionstring")); 

note notebookcontext entity framework model.

i write registration got error:

var builder = new containerbuilder(); builder.registertype<notebookcontext>()        .as<dbcontext>(); builder.registertype<unitofwork>()        .usingconstructor(typeof(dbcontext))        .as<iunitofwork>();  builder.registergeneric(typeof(repository<>))        .as(typeof(irepository<>))        .instanceperlifetimescope();  container container = builder.build(); 

this error:

an unhandled exception of type 'autofac.core.dependencyresolutionexception' occurred in autofac.dll additional information: none of constructors found 'autofac.core.activators.reflection.defaultconstructorfinder' on type 'datalayer.notebookcontext' can invoked available services , parameters:

cannot resolve parameter 'system.string connectionstring' of constructor 'void .ctor(system.string)'.

edit 2 :

after cyril durand's answer write following registering config:

 var builder = new containerbuilder();         builder.registertype<connectionstringprovider>().as<iconnectionstringprovider>();         builder.registertype<notebookcontext>().as<dbcontext>().withparameter((pi, c) => pi.name == "connectionstring",                                                                               (pi, c) => c.resolve<iconnectionstringprovider>().connectionstring);         builder.registertype<unitofwork>().as<iunitofwork>().withparameter(resolvedparameter.fornamed<dbcontext>("connectionstring"));         builder.registergeneric(typeof(repository<>)).as(typeof(irepository<>)).instanceperlifetimescope(); 

and in code :

using (var scope = dependencyinjection.container.beginlifetimescope())         {             var connectionstring = scope.resolve<iconnectionstringprovider>();             connectionstring.connectionstring = "context";              var uw = scope.resolve<iunitofwork>();             var =uw.contact.getall();          } 

but got error again:

an unhandled exception of type 'autofac.core.dependencyresolutionexception' occurred in autofac.dll

additional information: exception thrown while invoking constructor 'void .ctor(system.string)' on type 'notebookcontext'.

can me?

the error message :

an unhandled exception of type autofac.core.dependencyresolutionexception occurred in autofac.dll additional information: none of constructors found autofac.core.activators.reflection.defaultconstructorfinder on type datalayer.notebookcontext can invoked available services , parameters:

cannot resolve parameter system.string connectionstring of constructor void .ctor(system.string).

tells autofac can't create notebookcontext because can resolve parameter named connectionstring of type string.

your notebookcontext implementation needs connectionstring, autofac can't know without telling it. when register notebookcontext have specify connectionstring :

builder.registertype<notebookcontext>()        .as<dbcontext>()        .withparameter("connectionstring", "xxx"); 

another solution dynamic resolution , iconnectionstringprovider interface :

public interface iconnectionstringprovider {     public string connectionstring { get; } } 

and registration :

builder.registertype<connectionstringprovider>()        .as<iconnectionstringprovider>()        .instanceperlifetimescope();  builder.registertype<notebookcontext>()        .as<dbcontext>()        .withparameter((pi, c) => pi.name == "connectionstring",                        (pi, c) => c.resolve<iconnectionstringprovider>().connectionstring)        .instanceperlifetimescope();