Exception Details: System.ArgumentNullException: Value cannot be null. Parameter name: meth when running

Question

I am having a project in which I have my API classes and in that project I have generated the Database.cs. In my MVC project I have refenrenced the API. Uppon running the application I am having the error message as follows, can anyone help please as I can`t understand why I am having this error message.

From http://www.garethelms.org/2011/05/help-getting-started-with-petapoco/#comment-69, I can see that all the GetSetMethod() are GetSetMethod(true) ever since the petaPOCo is installed.

Value cannot be null. Parameter name: meth 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.ArgumentNullException: Value cannot be null. Parameter name: meth

Source Error:

Line 1990: } Line 1991: Line 1992: il.Emit(OpCodes.Callvirt, pc.PropertyInfo.GetSetMethod(true)); // poco Line 1993: Handled = true; Line 1994: }

Source File: C:\Dev\MyProjectTest\Code\API\Models\PetaPoco.cs Line: 1992

Stack Trace:

[ArgumentNullException: Value cannot be null. Parameter name: meth]
System.Reflection.Emit.DynamicILGenerator.Emit(OpCode opcode, MethodInfo meth) +9492330 PetaPoco.PocoData.GetFactory(String sql, String connString, Boolean ForceDateTimesToUtc, Int32 firstColumn, Int32 countColumns, IDataReader r) in C:\Dev\MyProjectTest\Code\API\Models\PetaPoco.cs:1992
PetaPoco.d__71.MoveNext() in C:\Dev\MyProjectTest\Code\API\Models\PetaPoco.cs:765
System.Collections.Generic.List1..ctor(IEnumerable1 collection) +327 System.Linq.Enumerable.ToList(IEnumerable1 source) +58
PetaPoco.Database.Fetch(String sql, Object[] args) in C:\Dev\MyProjectTest\Code\API\Models\PetaPoco.cs:601
PecaTest.NewProject.API.Customer.LoadSortedByName() in C:\Dev\MyProjectTest\Code\API\Customer.cs:68
PecaTest.NewProject.MvcUI.Models.CustomerListModel..ctor() in C:\Dev\MyProjectTest\Code\MvcUI\Models\CustomerListModel.cs:14
PecaTest.NewProject.MvcUI.Controllers.CustomerController.GetIndexView() in C:\Dev\MyProjectTest\Code\MvcUI\Controllers\CustomerController.cs:82
PecaTest.NewProject.MvcUI.Controllers.CustomerController.Index() in C:\Dev\MyProjectTest\Code\MvcUI\Controllers\CustomerController.cs:19
lambda_method(Closure , ControllerBase , Object[] ) +96
System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +51
System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary2 parameters) +409
System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary2 parameters) +52
System.Web.Mvc.<>c_DisplayClassd.b_a() +127 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func1 continuation) +436
System.Web.Mvc.<>c__DisplayClassf.<InvokeActionMethodWithFilters>b__c() +61 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func1 continuation) +436
System.Web.Mvc.<>c_DisplayClassf.b_c() +61 System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList1 filters, ActionDescriptor actionDescriptor, IDictionary2 parameters) +305
System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +830
System.Web.Mvc.Controller.ExecuteCore() +136
System.Web.Mvc.ControllerBase.Execute(RequestContext requestContext) +111 System.Web.Mvc.ControllerBase.System.Web.Mvc.IController.Execute(RequestContext requestContext) +39
System.Web.Mvc.<>c_DisplayClass8.b_4() +65
System.Web.Mvc.Async.<>c_DisplayClass1.b_0() +44
System.Web.Mvc.Async.<>c__DisplayClass81.<BeginSynchronous>b__7(IAsyncResult _) +42 System.Web.Mvc.Async.WrappedAsyncResult1.End() +140 System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +54
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +52 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +38
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8969117 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184

-------------------------------------------------------------------------------- Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.272

---

Customer class

` private int id = 0;
    public  int ID
    {
        get { return id; }
        set { id = ID; }
    }

    protected string name;
    public Customer() { }

    public Customer(string name)
    {
        this.name = name;
    }

    public string Name
    {
        get { return name; }
        set { name = value; }
    }

    public override string ToString()
    {
        return name;
    }

`

Answer 1

To make the accepted answer a bit more precise. I ran into this issue when I had a property in my POCO that matched the name of a column in the database table but I didn't have a setter for the property. In my case it was a property that I was computing myself so I didn't really need the data from the table and I intended it to be read-only. Adding an empty setter fixed the problem for me.

A likely better option would be to add the Ignore attribute to that property.

I ultimately ended up removing the column from the table.

Answer 2

Does your poco have a parameterless constructor ie; no arguments? It will need one. If you've created your own constructor with parameters you won't have a default parameterless constructor which could be causing the reflection code to fail. Maybe that's it.