The following code throws a NullReferenceException. If I filter user table using another column, exception is not throwed. DateTime type columns cause this exception.
using (MyDataContext dc = new MyDataContext())
{
var ids = dc.Users.Where(c => c.BirthDate < DateTime.Now.AddYears(-10)).Select(c => c.UserId);
var list = (from c in dc.Users
where ids.Contains(c.UserId)
select c).ToList();
}
Stack trace like this:
[NullReferenceException: Object reference not set to an instance of an object.]
System.Data.Linq.SqlClient.SqlFactory.Member(SqlExpression expr, MemberInfo member) +182
System.Data.Linq.SqlClient.QueryConverter.VisitMemberAccess(MemberExpression ma) +260
System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) +939
System.Data.Linq.SqlClient.QueryConverter.Visit(Expression node) +18
System.Data.Linq.SqlClient.QueryConverter.VisitExpression(Expression exp) +18
System.Data.Linq.SqlClient.QueryConverter.VisitMethodCall(MethodCallExpression mc) +1011
System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) +1003
System.Data.Linq.SqlClient.QueryConverter.Visit(Expression node) +18
System.Data.Linq.SqlClient.QueryConverter.VisitExpression(Expression exp) +18
System.Data.Linq.SqlClient.QueryConverter.VisitChangeType(Expression expression, Type type) +12
System.Data.Linq.SqlClient.QueryConverter.VisitCast(UnaryExpression c) +117
System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) +619
System.Data.Linq.SqlClient.QueryConverter.Visit(Expression node) +18
System.Data.Linq.SqlClient.QueryConverter.VisitExpression(Expression exp) +18
System.Data.Linq.SqlClient.QueryConverter.VisitBinary(BinaryExpression b) +35
System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) +427
System.Data.Linq.SqlClient.QueryConverter.Visit(Expression node) +18
System.Data.Linq.SqlClient.QueryConverter.VisitExpression(Expression exp) +18
System.Data.Linq.SqlClient.QueryConverter.VisitBinary(BinaryExpression b) +35
System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) +427
System.Data.Linq.SqlClient.QueryConverter.Visit(Expression node) +18
System.Data.Linq.SqlClient.QueryConverter.VisitExpression(Expression exp) +18
System.Data.Linq.SqlClient.QueryConverter.VisitWhere(Expression sequence, LambdaExpression predicate) +125
System.Data.Linq.SqlClient.QueryConverter.VisitSequenceOperatorCall(MethodCallExpression mc) +3403
System.Data.Linq.SqlClient.QueryConverter.VisitMethodCall(MethodCallExpression mc) +74
System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) +1003
System.Data.Linq.SqlClient.QueryConverter.Visit(Expression node) +18
System.Data.Linq.SqlClient.QueryConverter.VisitSelect(Expression sequence, LambdaExpression selector) +17
System.Data.Linq.SqlClient.QueryConverter.VisitSequenceOperatorCall(MethodCallExpression mc) +1368
System.Data.Linq.SqlClient.QueryConverter.VisitMethodCall(MethodCallExpression mc) +74
System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) +1003
System.Data.Linq.SqlClient.QueryConverter.Visit(Expression node) +18
System.Data.Linq.SqlClient.QueryConverter.VisitContains(Expression sequence, Expression value) +377
System.Data.Linq.SqlClient.QueryConverter.VisitSequenceOperatorCall(MethodCallExpression mc) +9129
System.Data.Linq.SqlClient.QueryConverter.VisitMethodCall(MethodCallExpression mc) +74
System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) +1003
System.Data.Linq.SqlClient.QueryConverter.Visit(Expression node) +18
System.Data.Linq.SqlClient.QueryConverter.VisitExpression(Expression exp) +18
System.Data.Linq.SqlClient.QueryConverter.VisitWhere(Expression sequence, LambdaExpression predicate) +125
System.Data.Linq.SqlClient.QueryConverter.VisitSequenceOperatorCall(MethodCallExpression mc) +3403
System.Data.Linq.SqlClient.QueryConverter.VisitMethodCall(MethodCallExpression mc) +74
System.Data.Linq.SqlClient.QueryConverter.VisitInner(Expression node) +1003
System.Data.Linq.SqlClient.QueryConverter.ConvertOuter(Expression node) +79
System.Data.Linq.SqlClient.SqlProvider.BuildQuery(Expression query, SqlNodeAnnotations annotations) +114
System.Data.Linq.SqlClient.SqlProvider.System.Data.Linq.Provider.IProvider.Execute(Expression query) +132
System.Data.Linq.DataQuery`1.System.Collections.Generic.IEnumerable<T>.GetEnumerator() +35
System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) +7667686
System.Linq.Enumerable.ToList(IEnumerable`1 source) +61
lab_test.Page_Load(Object sender, EventArgs ee) in d:\Projeler\Kardelen\Kod\Kardelen.Web.UI\lab\test.aspx.cs:543
System.Web.Util.CalliHelper.EventArgFunctionCaller(IntPtr fp, Object o, Object t, EventArgs e) +14
System.Web.Util.CalliEventHandlerDelegateProxy.Callback(Object sender, EventArgs e) +35
System.Web.UI.Control.OnLoad(EventArgs e) +99
System.Web.UI.Control.LoadRecursive() +50
System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +627
Is anybody get this exception?
Thanks for response.
If I filter user table using another column, exception is not throwed. DateTime type columns cause this exception.
Assuming you mean this comparison: c.BirthDate < DateTime.Now.AddYears(-10)
Most likely BirthDate
is null
. In case it is sufficient in your scenario to just skip those users, you can add a check to see whether it is null before doing the date comparison.
As a sidenote, you should probably define DateTime.Now.AddYears(-10)
once before calling Where
to prevent it from being recalculated, and worse from the value changing over time.
DateTime tenYearsAgo = DateTime.Now.AddYears(-10);
var ids = dc.Users
.Where(c => c.BirthDate != null && c.BirthDate < tenYearsAgo)
.Select(c => c.UserId);
Most likely your c.BirthDate
property is nullable , DateTime? BirthDate
DateTime? BirthDate
.
That would match an Allow-NULL column in your table.
A simple check should be enough:
dc.Users.Where(c => c.BirthDate.HasValue
&& (c.BirthDate < DateTime.Now.AddYears(-10))
)
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