"dm1608" wrote:

> I'm doing an ASP.NET 2.0 project where I have a BAL and DAL layer.  I'm
> passing a DataSet from the DAL to the BAL.  The BAL is passing generics back
> to the presentation.  All works fine, however, I noticed a problem with my
> code that does something like this in the BAL:
>
>
> List<JobSummary> jobSummary = new List<JobSummary>();
>
> foreach (DataRow row in ds.Tables[0].Rows)
> {
>    jobSummary.Add(new JobSummaryClass((Int32)row["JobNum"],
> (DateTime)row["StartDate"],(DateTime)row["EndDate"]));
> }
>
> return jobSummary
>
>
> I'm receiving an INvalidCastException on my jobSummary.Add() above.  I
> noticed that on some rows, my EndTime is null.  I'm temporarily fixed this
> by enclosing the code in a try/catch and not rethrowing the exception.  But
> then this record is skipped.
>
> What are my options with how to fix this?
>
>
>
>

"Elton W" <Elt***@discussions.microsoft.com> wrote in message
news:EA8CD012-4D2B-4B93-B0F1-D3786F7D80E2@microsoft.com...
> You can use
>
>
> if (row["StartDate"] != DBNull.Value)
> {
>  //
> }
>
> or
> if (!row.IsNull("StartDate"))
> {
> //
> }
>
>
> HTH
>
> Elton Wang
>
> "dm1608" wrote:
>
>> I'm doing an ASP.NET 2.0 project where I have a BAL and DAL layer.  I'm
>> passing a DataSet from the DAL to the BAL.  The BAL is passing generics
>> back
>> to the presentation.  All works fine, however, I noticed a problem with
>> my
>> code that does something like this in the BAL:
>>
>>
>> List<JobSummary> jobSummary = new List<JobSummary>();
>>
>> foreach (DataRow row in ds.Tables[0].Rows)
>> {
>>    jobSummary.Add(new JobSummaryClass((Int32)row["JobNum"],
>> (DateTime)row["StartDate"],(DateTime)row["EndDate"]));
>> }
>>
>> return jobSummary
>>
>>
>> I'm receiving an INvalidCastException on my jobSummary.Add() above.  I
>> noticed that on some rows, my EndTime is null.  I'm temporarily fixed
>> this
>> by enclosing the code in a try/catch and not rethrowing the exception.
>> But
>> then this record is skipped.
>>
>> What are my options with how to fix this?
>>
>>
>>
>>

"Rune B" <yeahri***@bingo.com> wrote in message
news:OqTz1QzNGHA.3908@TK2MSFTNGP10.phx.gbl...
>> But I need to assign NULL to the EndTime DateTime variable in order to
>> populate my collection for display.  How do I get around this?
>
> How about using a Nullable DateTime? - and then don't assign anything if
> the value is DBNull.
>
> class JobSummaryItem
> {
>    //    ...
>
>    public DateTime? EndTime
>    {
>        get { ... }
>    }
> }
>

"Rune B" <yeahri***@bingo.com> wrote in message
news:uwELFZ0NGHA.2176@TK2MSFTNGP10.phx.gbl...
>> Can you further describe this.  Is DateTime? EndTime some sort of C#
>> shorthand?
>>
>> Basically, the database has NULL for the EndTime and I still need to
>> display it as a blank field within the GridView.  The issue is that my
>> JobSummary class is defined as accepting the EndTime as a DateTime
>> datatype.  I guess I cannot assign NULL to a DateTime datatype???
>
> Not really, the Nullable class encapsulates the DateTime type.. it is
> really a generic class, used for this purpose ... to make value types able
> to be null
> type is    NullAble<DateTime>
> shorthand is DateTime?
>
> But You can have a field like this:
>
> private DateTime? _endtime = null;
>
> // and later aks if it has a value
>
> if(_endtime == null)
> {
>    _endtime = DateTime.Now;
> }
> return _endtime.Value;
>
>
> and so on ... I find it very usable for values where it is important to
> track whether thay have been assigned or not.
>
>

"dm1608" <dm1608@spam.net> wrote in message
news:u$QQ350NGHA.668@TK2MSFTNGP11.phx.gbl...
> I'm still having issues with trying to use the DateTime? within my
> classes. I will attempt to work on it again tomorrow and post more code
> here if I can't get it to work.   Even though I changed all my references
> from DateTime to DateTime?, it looks like it still doesn't like the NULL
> coming back from the database.

"Rune B" <yeahri***@bingo.com> wrote in message
news:ebveQY4NGHA.2992@tk2msftngp13.phx.gbl...
> That could be the fact that    row["EndDate"]   really returns DBNull and
> not 'null'
>
> - you should consider doing what 'Elton W' suggested in the very first
> reply
>
>
> "dm1608" <dm1608@spam.net> wrote in message
> news:u$QQ350NGHA.668@TK2MSFTNGP11.phx.gbl...
>> I'm still having issues with trying to use the DateTime? within my
>> classes. I will attempt to work on it again tomorrow and post more code
>> here if I can't get it to work.   Even though I changed all my references
>> from DateTime to DateTime?, it looks like it still doesn't like the NULL
>> coming back from the database.
>
>

"dm1608" wrote:

> I'm still working on this and haven't spent much time today on it.  Stayed
> up late last night trying different things.
>
> My DAL is returning a DataSet to the BAL.
>
> My BAL is looping thru each record of the DataSet and adding each field to
> my generic collection of type JobSummary.
>
> The generic collection from the BAL is returned to ASP.NET ObjectDataSource
> for display within a GridView control.
>
> I verified that when I receive an InvalidCastException that the
> row["EndTime"] field is indeed null.  The type shows sqlDBNull in the watch
> window.
>
> Using the nullable DateTime? time doesn't appear to help.  Trying to pass
> the fields to my Add() collection fails each time... and I changed all the
> DateTime references within my type class to use DateTime?.
>
> Looking back at "Elton W" suggestion doesn't make much sense to me.  I mean,
> even if I verify that it is null or not, then what?   I still got to pass a
> valid DateTime type to my collection.
>
> I want to pass either a valid date (which appears to work when the field
> contains it) or NULL so that the GridView will simply display blank for that
> item.  Essentially... a job is still running if it doesn't have an EndTime.
> So it's a perfectly valid case.
>
>
>
>
> "Rune B" <yeahri***@bingo.com> wrote in message
> news:ebveQY4NGHA.2992@tk2msftngp13.phx.gbl...
> > That could be the fact that    row["EndDate"]   really returns DBNull and
> > not 'null'
> >
> > - you should consider doing what 'Elton W' suggested in the very first
> > reply
> >
> >
> > "dm1608" <dm1608@spam.net> wrote in message
> > news:u$QQ350NGHA.668@TK2MSFTNGP11.phx.gbl...
> >> I'm still having issues with trying to use the DateTime? within my
> >> classes. I will attempt to work on it again tomorrow and post more code
> >> here if I can't get it to work.   Even though I changed all my references
> >> from DateTime to DateTime?, it looks like it still doesn't like the NULL
> >> coming back from the database.
> >
> >
>
>
>

"Elton W" <Elt***@discussions.microsoft.com> wrote in message
news:91FE8331-D392-4E03-8065-D71337584D12@microsoft.com...
> if it's DBNull.Value, you can set EndTime to DateTime.MaxValue. In
> GridView,
> if it's DateTime.MaxValue show Not End.
>
> HTH
>
> Elton Wang
>
> "dm1608" wrote:
>
>> I'm still working on this and haven't spent much time today on it.
>> Stayed
>> up late last night trying different things.
>>
>> My DAL is returning a DataSet to the BAL.
>>
>> My BAL is looping thru each record of the DataSet and adding each field
>> to
>> my generic collection of type JobSummary.
>>
>> The generic collection from the BAL is returned to ASP.NET
>> ObjectDataSource
>> for display within a GridView control.
>>
>> I verified that when I receive an InvalidCastException that the
>> row["EndTime"] field is indeed null.  The type shows sqlDBNull in the
>> watch
>> window.
>>
>> Using the nullable DateTime? time doesn't appear to help.  Trying to pass
>> the fields to my Add() collection fails each time... and I changed all
>> the
>> DateTime references within my type class to use DateTime?.
>>
>> Looking back at "Elton W" suggestion doesn't make much sense to me.  I
>> mean,
>> even if I verify that it is null or not, then what?   I still got to pass
>> a
>> valid DateTime type to my collection.
>>
>> I want to pass either a valid date (which appears to work when the field
>> contains it) or NULL so that the GridView will simply display blank for
>> that
>> item.  Essentially... a job is still running if it doesn't have an
>> EndTime.
>> So it's a perfectly valid case.
>>
>>
>>
>>
>> "Rune B" <yeahri***@bingo.com> wrote in message
>> news:ebveQY4NGHA.2992@tk2msftngp13.phx.gbl...
>> > That could be the fact that    row["EndDate"]   really returns DBNull
>> > and
>> > not 'null'
>> >
>> > - you should consider doing what 'Elton W' suggested in the very first
>> > reply
>> >
>> >
>> > "dm1608" <dm1608@spam.net> wrote in message
>> > news:u$QQ350NGHA.668@TK2MSFTNGP11.phx.gbl...
>> >> I'm still having issues with trying to use the DateTime? within my
>> >> classes. I will attempt to work on it again tomorrow and post more
>> >> code
>> >> here if I can't get it to work.   Even though I changed all my
>> >> references
>> >> from DateTime to DateTime?, it looks like it still doesn't like the
>> >> NULL
>> >> coming back from the database.
>> >
>> >
>>
>>
>>

"dm1608" <dm1608@spam.net> wrote in message
news:uSOEz$IOGHA.3788@TK2MSFTNGP09.phx.gbl...
> Hi -- can you clarify the DateTime.MaxDate.   I'm not familiar with what
> this is even for or how it can be used, much less the DateTime.MinDate.
>
>
>
> "Elton W" <Elt***@discussions.microsoft.com> wrote in message
> news:91FE8331-D392-4E03-8065-D71337584D12@microsoft.com...
>> if it's DBNull.Value, you can set EndTime to DateTime.MaxValue. In
>> GridView,
>> if it's DateTime.MaxValue show Not End.
>>
>> HTH
>>
>> Elton Wang
>>
>> "dm1608" wrote:
>>
>>> I'm still working on this and haven't spent much time today on it.
>>> Stayed
>>> up late last night trying different things.
>>>
>>> My DAL is returning a DataSet to the BAL.
>>>
>>> My BAL is looping thru each record of the DataSet and adding each field
>>> to
>>> my generic collection of type JobSummary.
>>>
>>> The generic collection from the BAL is returned to ASP.NET
>>> ObjectDataSource
>>> for display within a GridView control.
>>>
>>> I verified that when I receive an InvalidCastException that the
>>> row["EndTime"] field is indeed null.  The type shows sqlDBNull in the
>>> watch
>>> window.
>>>
>>> Using the nullable DateTime? time doesn't appear to help.  Trying to
>>> pass
>>> the fields to my Add() collection fails each time... and I changed all
>>> the
>>> DateTime references within my type class to use DateTime?.
>>>
>>> Looking back at "Elton W" suggestion doesn't make much sense to me.  I
>>> mean,
>>> even if I verify that it is null or not, then what?   I still got to
>>> pass a
>>> valid DateTime type to my collection.
>>>
>>> I want to pass either a valid date (which appears to work when the field
>>> contains it) or NULL so that the GridView will simply display blank for
>>> that
>>> item.  Essentially... a job is still running if it doesn't have an
>>> EndTime.
>>> So it's a perfectly valid case.
>>>
>>>
>>>
>>>
>>> "Rune B" <yeahri***@bingo.com> wrote in message
>>> news:ebveQY4NGHA.2992@tk2msftngp13.phx.gbl...
>>> > That could be the fact that    row["EndDate"]   really returns DBNull
>>> > and
>>> > not 'null'
>>> >
>>> > - you should consider doing what 'Elton W' suggested in the very first
>>> > reply
>>> >
>>> >
>>> > "dm1608" <dm1608@spam.net> wrote in message
>>> > news:u$QQ350NGHA.668@TK2MSFTNGP11.phx.gbl...
>>> >> I'm still having issues with trying to use the DateTime? within my
>>> >> classes. I will attempt to work on it again tomorrow and post more
>>> >> code
>>> >> here if I can't get it to work.   Even though I changed all my
>>> >> references
>>> >> from DateTime to DateTime?, it looks like it still doesn't like the
>>> >> NULL
>>> >> coming back from the database.
>>> >
>>> >
>>>
>>>
>>>
>
>

"Rune B" <yeahri***@bingo.com> wrote in message
news:%23kp0nYEOGHA.2604@TK2MSFTNGP09.phx.gbl...
>> Using the nullable DateTime? time doesn't appear to help.  Trying to pass
>> the fields to my Add() collection fails each time... and I changed all
>> the DateTime references within my type class to use DateTime?.
>>
>> Looking back at "Elton W" suggestion doesn't make much sense to me.  I
>> mean, even if I verify that it is null or not, then what?   I still got
>> to pass a valid DateTime type to my collection.
>
> I think what he suggested was instead of the very optimistic filling:
> (DateTime)row["EndDate"]
>
> you should check whether content is null or not first, (wrap it in a
> function)
>
> DateTime? enddate;
> object obj = row["EndDate"];
> if(obj != null)
>    enddate = (DateTime);
>
>
>
>

> private Int16 _JobNum;
> private string _Status;
> private DateTime? _TimeStart;
> private DateTime? _TimeEnd;
> private DateTime? _JobName;
>
> Then I do my constructor and the get/set functions...
>
> public Int16 JobNum
> {
>   get { return _JobNum; }
>   set { _JobNum = value; }
> }
>
> If my query in the DAL has 15 fields, it takes a while to create my type
> class for this.   I'm wondering if I can easily do this thru Visual Studio
> or some other product.

"Rune B" wrote:

> > private Int16 _JobNum;
> > private string _Status;
> > private DateTime? _TimeStart;
> > private DateTime? _TimeEnd;
> > private DateTime? _JobName;
> >
> > Then I do my constructor and the get/set functions...
> >
> > public Int16 JobNum
> > {
> >   get { return _JobNum; }
> >   set { _JobNum = value; }
> > }
> >
> > If my query in the DAL has 15 fields, it takes a while to create my type
> > class for this.   I'm wondering if I can easily do this thru Visual Studio
> > or some other product.
>
>
> You'll be amazed how quick it will be to code even a 50 field class,
> properties, fields and all, if you use the snippets in Visual Studio 2005.
>
> try this:
>
> within the class {  } brackets type: prop[tab]
> - meaning the letters p-r-o-p and then press the [TAB]-key, - if the
> intellisence kicks in, press tab once more.
> - then you'll see the outline for a complete property with fields and all.
>
> After that you can tab between the green variable fields in the snippet, and
> when you're done, press [enter]
>
> ----
>
> There's a lot of different snippets, but this is the one I use the most.
> Snippets basically eliminates 90% of all the basic repetitive plumbing.
>
>
> my favorites:
> prop
> propg
> ctor
> exception
>
> R-)
>
>
>

"dm1608" wrote:

> But I need to assign NULL to the EndTime DateTime variable in order to
> populate my collection for display.  How do I get around this?
>
>
>
>
> "Elton W" <Elt***@discussions.microsoft.com> wrote in message
> news:EA8CD012-4D2B-4B93-B0F1-D3786F7D80E2@microsoft.com...
> > You can use
> >
> >
> > if (row["StartDate"] != DBNull.Value)
> > {
> >  //
> > }
> >
> > or
> > if (!row.IsNull("StartDate"))
> > {
> > //
> > }
> >
> >
> > HTH
> >
> > Elton Wang
> >
> > "dm1608" wrote:
> >
> >> I'm doing an ASP.NET 2.0 project where I have a BAL and DAL layer.  I'm
> >> passing a DataSet from the DAL to the BAL.  The BAL is passing generics
> >> back
> >> to the presentation.  All works fine, however, I noticed a problem with
> >> my
> >> code that does something like this in the BAL:
> >>
> >>
> >> List<JobSummary> jobSummary = new List<JobSummary>();
> >>
> >> foreach (DataRow row in ds.Tables[0].Rows)
> >> {
> >>    jobSummary.Add(new JobSummaryClass((Int32)row["JobNum"],
> >> (DateTime)row["StartDate"],(DateTime)row["EndDate"]));
> >> }
> >>
> >> return jobSummary
> >>
> >>
> >> I'm receiving an INvalidCastException on my jobSummary.Add() above.  I
> >> noticed that on some rows, my EndTime is null.  I'm temporarily fixed
> >> this
> >> by enclosing the code in a try/catch and not rethrowing the exception.
> >> But
> >> then this record is skipped.
> >>
> >> What are my options with how to fix this?
> >>
> >>
> >>
> >>
>
>
>