I have a table DivorceCases which has many fields and it's model is like:
[Key]
[Required]
public string case_id { get; set; }
public string user_id { get; set; }
public DateTime case_date { get; set; }
public virtual Transactions t { get; set; }
I am trying to add transaction details to an existing row but I am getting a [NullReferenceException: Object reference not set to an instance of an object.] error. In the DivorceCases table EF6 has created a column t_id for foreign key reference of Transactions Table.
I used :
public static void UpdatePayment(string cid,string txnno)
{
DivorceCasesContext db = new DivorceCasesContext();
DivorceCases dc = db.DivorceCase.Where(x => x.case_id == cid).Include(x => x.t).SingleOrDefault();
if (dc.t == null || dc.t.txn_id1 == null || dc.t.txn_id1 == "")
{
dc.t.txn_id1 = txnno;
dc.t.amount1 = amount.ToString();
dc.t.date1 = DateTime.Now.ToString();
}
else
{
dc.t.txn_id2 = txnno;
dc.t.amount2 = amount.ToString();
dc.t.date2 = DateTime.Now.ToString();
}
db.Set<DivorceCases>().Attach(dc);
db.Entry(dc).State = EntityState.Modified;
db.SaveChanges();
}
}
The Error I'm getting is:
[NullReferenceException: Object reference not set to an instance of an object.]
gonylaw.Helpers.Amounts.UpdatePayment(String cid, String txnno) +425
gonylaw.Controllers.PaymentController.PaymentProcessor(CreditCard c) +461
lambda_method(Closure , ControllerBase , Object[] ) +104
System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +14
System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +157
System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +27
System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState) +22
System.Web.Mvc.Async.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult) +29
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +32
System.Web.Mvc.Async.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d() +50
System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +225
System.Web.Mvc.Async.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) +10
System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +34
System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +26
System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +100
System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +27
System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +13
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +36
System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) +12
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +22
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26
System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +21
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +28
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9644037
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155
You are accessing properties of dc.t
without ensuring dc.t
is not null. If the if
statement short circuits on the first condition, dc.t
is null, yet you attempt to assign a value to dc.t.txn_id
:
if( dc.t == null || ... )
{
dc.t.txn_id1 = txnno; // null ref exception here
}
Asside from that, there are other improvements I suggest:
public static void UpdatePayment(string cid,string txnno)
{
// add using block to dispose of DbContext after you're done with it
using( DivorceCasesContext db = new DivorceCasesContext() )
{
DivorceCases dc = db.DivorceCase.Include(x => x.t)
.Where( x => x.case_id == cid )
.SingleOrDefault();
// take care of your null ref problem
if( dc.t == null )
{
dc.t = new Transactions();
}
// simplify null/empty string check
if( string.IsNullOrEmpty( dc.t.txn_id1 ) )
{
dc.t.txn_id1 = txnno;
dc.t.amount1 = amount.ToString();
dc.t.date1 = DateTime.Now.ToString();
}
else
{
dc.t.txn_id2 = txnno;
dc.t.amount2 = amount.ToString();
dc.t.date2 = DateTime.Now.ToString();
}
// this is not needed - dc is already attached to the context
// (unless you're doing something nonstandard by default
// within your DbContext)
//db.Set<DivorceCases>().Attach(dc);
//db.Entry(dc).State = EntityState.Modified;
db.SaveChanges();
}
}
}
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