CODEWITHSUNDEEP
c#linq-to-sql
Bruno Machado - vargero
Bruno Machado - vargero

Reputation: 2730

Problem with Linq to SQL

I've been working with Linq to SQL for some time now, and I never had a problem ... until now. I have a method that send a query to the database, but different from the other times I did it, I cannot cast the result (be it to List or to Array). The method look as follows:

public List<vwContainer> GetConteinerPorto(int id)
{
    return (from cont in db.vwContainers
            where cont.idHarbor == id
            orderby cont.Year
            select cont).ToList();
}

I tried some variations of it, but it always result with a "Specified cast is not valid." exception being thrown. Can you guys give me some light?

Stacktrace:

[InvalidCastException: Specified cast is not valid.]
   System.Data.SqlClient.SqlBuffer.get_Int32() +6271252
   Read_vwCargas_movimentadas_conteiner(ObjectMaterializer`1 ) +636
   System.Data.Linq.SqlClient.ObjectReader`2.MoveNext() +42
   System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) +472
   System.Linq.Enumerable.ToList(IEnumerable`1 source) +80
   WebPortosSEP.Web.Models.PortoRepository.GetConteinerPorto(Int32 id) +867
   WebPortosSEP.Web.Controllers.PortoController.Cargas(Int32 id) +255
   lambda_method(Closure , ControllerBase , Object[] ) +112
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +258
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +39
   System.Web.Mvc.<>c__DisplayClassd.<InvokeActionMethodWithFilters>b__a() +125
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodFilter(IActionFilter filter, ActionExecutingContext preContext, Func`1 continuation) +640
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethodWithFilters(ControllerContext controllerContext, IList`1 filters, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +312
   System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName) +709
   System.Web.Mvc.Controller.ExecuteCore() +162
   System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__4() +58
   System.Web.Mvc.Async.<>c__DisplayClass1.<MakeVoidDelegate>b__0() +20
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +453
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +371

Upvotes: 1

Views: 2258

Answers (6)

Erik Funkenbusch
Erik Funkenbusch

Reputation: 93444

If it's a runtime exception and not a compile tome error, then the problem is almost surely that your dbml file is out of sync with your database on some level. I have also seem similar problems when you have more than one dbml file in the same namespace.

Try deleting the table in question out of the dbml file and recreate it.

UPDATE:

Based on your stacktrace, I find it highly suspicious that your exception occurs within a lambda method, but the code you have sown does not include any lambdas. That's not to say there might not be an internal lambda going on, but I don't think so.

Also, note that your stack trace includes this:

Read_vwCargas_movimentadas_conteiner

That's different from the code you posted.

Update 2:

The exception is occuring in an Int32 conversion, which suggests that one of your data columns is not correctly defined. Did you change the type from nullable to non-nullable?

Upvotes: 0

DamienG
DamienG

Reputation: 6665

It's possible you changed the database schema (e.g. an into to a string) and didn't update the DBML (you would only see this error at runtime when you first access the table that has the error)

Upvotes: 0

Unmesh Kondolikar
Unmesh Kondolikar

Reputation: 9312

This might be because of the mismatch between the types of columns in the database and the .Net types.

When the values of fields like cont.idHarbor and cont.Year are read from the database and converted to .Net types the resulting types may not match those of the properties in your class.

Check if idHarbor is bigInt in database and you are comparing it with an int. Also check the Year field types. You can take a clue from the stacktrace. Is the exception thrown by SqlDataReader.GetInt64 or any such similar method?

Upvotes: 4

dexter
dexter

Reputation: 7213

Try this:

 public List<vwContainer> GetConteinerPorto(int id) 
 { 
    return (from cont in db.vwContainers 
           where cont.idHarbor == id 
           orderby cont.Year 
           select cont).ToList<vwContainer>(); 
 }

Upvotes: 0

codymanix
codymanix

Reputation: 29520

Your method does not contain any cast. Are your sure the Exception is throw from within the method and not from its call site?

Upvotes: 0

msarchet
msarchet

Reputation: 15242

It would seem that cont is not actually a vwContainer.

Upvotes: 2

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