TimeSpan

[shapper]

Hello,

I have the following:

boxStat = new BoxStat {
BoxCount = database.Boxes. Count(),
SinceLastCreate = (DateTime.Now - database.Boxes. Max(b =>
b.CreatedAt)).D ays ?? 0
};

I am getting an error:
'System.Nullabl e<System.TimeSp an>' does not contain a definition for
'Days' and no extension method 'Days' accepting a first argument of
type 'System.Nullabl e<System.TimeSp an>' could be found (are you
missing a using directive or an assembly reference?)

I added ?? 0 to try to solve the problem but I keep having the same
error.

What am I doing wrong?

Thank You,
Miguel

[gerry]

Re: TimeSpan

For whatever reason , DateTime math has always seemed to require an explicit
cast to TimeSpan :

SinceLastCreate = ( (TimeSpan) (DateTime.Now - database.Boxes. Max(b
=b.CreatedAt)) ).Days


"shapper" <mdmoura@gmail. comwrote in message
news:85d99938-52b1-448a-ab39-47e28cb62f55@p4 9g2000hsd.googl egroups.com...

Hello,
>
I have the following:
>
boxStat = new BoxStat {
BoxCount = database.Boxes. Count(),
SinceLastCreate = ((TimeSpan)(Dat eTime.Now - database.Boxes. Max(b
=>
b.CreatedAt))). Days ?? 0
};
>
I am getting an error:
'System.Nullabl e<System.TimeSp an>' does not contain a definition for
'Days' and no extension method 'Days' accepting a first argument of
type 'System.Nullabl e<System.TimeSp an>' could be found (are you
missing a using directive or an assembly reference?)
>
I added ?? 0 to try to solve the problem but I keep having the same
error.
>
What am I doing wrong?
>
Thank You,
Miguel

[Hans Kesting]

Re: TimeSpan

shapper has brought this to us :

Hello,
>
I have the following:
>
boxStat = new BoxStat {
BoxCount = database.Boxes. Count(),
SinceLastCreate = (DateTime.Now - database.Boxes. Max(b =>
b.CreatedAt)).D ays ?? 0
};
>
I am getting an error:
'System.Nullabl e<System.TimeSp an>' does not contain a definition for
'Days' and no extension method 'Days' accepting a first argument of
type 'System.Nullabl e<System.TimeSp an>' could be found (are you
missing a using directive or an assembly reference?)
>
I added ?? 0 to try to solve the problem but I keep having the same
error.
>
What am I doing wrong?
>
Thank You,
Miguel

What does "database.Boxes .Max()" return? I'm guessing a nullable
DateTime (either "DateTime?" or "Nullable<DateT ime>", they are the
same).

That means that that difference will not return a TimeSpan, but a
nullable TimeSpan.
That "TimeSpan?" does not have a "Days" property, but it has a Value
property that returns a TimeSpan. That *does* have a Days property.
(DateTime.Now - database.Boxes. Max(b =b.CreatedAt)). Value.Days

Note: this fails if that Max returns a null!


You could have used that ?? operator, but then at the point where a
nullable type was involved:
((DateTime.Now - database.Boxes. Max(b =b.CreatedAt)) ??
TimeSpan.Zero). Days
This way you get 0 days when Max returned null.

Or (as gerry suggested) cast to TimeSpan before reading the Days
property. But this also fails when Max returns null.

Hans Kesting