با عرض سلام خدمت دوستان عزیز
من به این مشکل برخوردم لطفا راهنمایی کنید
در پروژه asp از حالت برنامه نویسی entity framwork استفاده کردم (Domain , UI )
کلاس Product رو ایجاد کرد Model > Repository > Service و از سرویس استفاده می کنم
و DataGarid رو به سرویس از طریق ObjectDatasource متصل کردم و هنگام اجرا این خطا رو می ده




No parameterless constructor defined for this object.

Description: An unhandled exception occurred during the execution of the  current web request. Please review the stack trace for more information  about the error and where it originated in the code.



Exception Details: System.MissingMethodException: No parameterless constructor defined for this object.



Source Error:



An unhandled exception was generated during the execution of the current  web request. Information regarding the origin and location of the  exception can be identified using the exception stack trace below.



Stack Trace:



[MissingMethodException: No parameterless constructor defined for this object.]

   System.RuntimeTypeHandle.CreateInstance(RuntimeTyp  e type, Boolean  publicOnly, Boolean noCheck, Boolean& canBeCached,  RuntimeMethodHandleInternal& ctor, Boolean& bNeedSecurityCheck)  +0

   System.RuntimeType.CreateInstanceSlow(Boolean publicOnly, Boolean  skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark) +113

   System.RuntimeType.CreateInstanceDefaultCtor(Boole  an publicOnly,  Boolean skipCheckThis, Boolean fillCache, StackCrawlMark& stackMark)  +232

   System.Activator.CreateInstance(Type type, Boolean nonPublic) +83

   System.Activator.CreateInstance(Type type) +6

    System.Web.UI.WebControls.ObjectDataSourceView.Inv  okeMethod(ObjectDataSourceMethod  method, Boolean disposeInstance, Object& instance) +125

   System.Web.UI.WebControls.ObjectDataSourceView.Exe  cuteSelect(DataSourceSelectArguments arguments) +1609

   System.Web.UI.WebControls.ListControl.OnDataBindin  g(EventArgs e) +101

   System.Web.UI.WebControls.ListControl.PerformSelec  t() +34

   System.Web.UI.WebControls.BaseDataBoundControl.Dat  aBind() +30

   System.Web.UI.WebControls.BaseDataBoundControl.Ens  ureDataBound() +105

   System.Web.UI.WebControls.ListControl.OnPreRender(  EventArgs e) +23

   System.Web.UI.Control.PreRenderRecursiveInternal() +83

   System.Web.UI.Control.PreRenderRecursiveInternal() +168

   System.Web.UI.Control.PreRenderRecursiveInternal() +168

   System.Web.UI.Control.PreRenderRecursiveInternal() +168

   System.Web.UI.Control.PreRenderRecursiveInternal() +168

   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +974