code in class versus aspx page

[GaryB]

The following line of code works fine in my code-behind file for an aspx
page:

Dim HeadingRow As DataRow = dsGridReport.Ta bles(0).NewRow( )

But when I transport that same code to a class and run it I get

"Object reference not set to an instance of an object"

Why?
Gary

[John M Deal]

Re: code in class versus aspx page

When you move it to a class I'm guessing you mean on separate from the
code behind class and that you are putting the line into a method of
some sort. Given this scenario you could end up with this problem for a
number of reasons:

First if you don't pass an instance of the dataset (dsGridReport) to the
class either as a property, a member lever variable, or a parameter of
the method it wouldn't be able to be seen by the line of code. This is
if the dataset is being created in the aspx page or its code behind.

Second would be if the dataset didn't have a table in it. This could be
caused if you were creating a data table and adding it to the table in
the codebehind, but are no longer doing that. In this instance you need
to make sure that you fully build the datatable and its column
definitions prior to trying to add a row to it. This can happen either
by filling the dataset from a datasource or by manually creating the
datatable and defining its columns.

These are the two ideas that spring to mind at this point. When you
string together the calls to objects like this it is hard to pinpoint
which one is causing the problem given limited information like this. To
get a better idea of what the actual issue is I'd set a break point on
the line and use the locals and or immediate/command window to find out
which object really has the issue then resolve where it would be created
and how that needs to be corrected for the line of code in question to
succeed.

Sorry I couldn't be more help.

Have A Better One!

John M Deal, MCP
Necessity Software

GaryB wrote:[color=blue]
> The following line of code works fine in my code-behind file for an aspx
> page:
>
> Dim HeadingRow As DataRow = dsGridReport.Ta bles(0).NewRow( )
>
> But when I transport that same code to a class and run it I get
>
> "Object reference not set to an instance of an object"
>
> Why?
> Gary
>
>[/color]

[Kevin Spencer]

Re: code in class versus aspx page

An ASPX Page IS a class. So, what you're saying is, if you move a single
line of code in one class that has no problems in that class where you have
it, to another class (where in that class, you don't mention), it throws an
exception. And you want to know why?

....

....

....

Step away from the computer. Slowly.

--
;-),
Kevin Spencer
..Net Developer
Microsoft MVP
Neither a follower
nor a lender be.

"GaryB" <gb@nospam.co m> wrote in message
news:OL6bytdzEH A.3120@TK2MSFTN GP12.phx.gbl...[color=blue]
> The following line of code works fine in my code-behind file for an aspx
> page:
>
> Dim HeadingRow As DataRow = dsGridReport.Ta bles(0).NewRow( )
>
> But when I transport that same code to a class and run it I get
>
> "Object reference not set to an instance of an object"
>
> Why?
> Gary
>
>[/color]

[Kevin Spencer]

Re: code in class versus aspx page

Okay, I'm trying to calm down from my incredulity, so that I can give you a
useful answer.

That single line of code is ONLY going to work in a method of a class which
has declared AND instantiated a DataSet named "dsGridRepo rt." In addition,
that DataSet must contain at least ONE table. If either the DataSet named in
that line of code doesn't exist, OR it has no tables in it, you will get the
exception you describe, as you are referencing an object (either
dsGridReport or its' table) that doesn't exist in that method or class.

You wouldn't take a carbeurator out of your car, stick it in another car of
another type, and expect it to work, would you?

--
HTH,
Kevin Spencer
..Net Developer
Microsoft MVP
Neither a follower
nor a lender be.

"GaryB" <gb@nospam.co m> wrote in message
news:OL6bytdzEH A.3120@TK2MSFTN GP12.phx.gbl...[color=blue]
> The following line of code works fine in my code-behind file for an aspx
> page:
>
> Dim HeadingRow As DataRow = dsGridReport.Ta bles(0).NewRow( )
>
> But when I transport that same code to a class and run it I get
>
> "Object reference not set to an instance of an object"
>
> Why?
> Gary
>
>[/color]

[GaryB]

Re: code in class versus aspx page

Wow, a flame from a weenie. It's been years.
Gary :)

"Kevin Spencer" <kspencer@takem pis.com> wrote in message
news:O57H1FkzEH A.2040@tk2msftn gp13.phx.gbl...[color=blue]
> Okay, I'm trying to calm down from my incredulity, so that I can give you
> a
> useful answer.
>
> That single line of code is ONLY going to work in a method of a class
> which
> has declared AND instantiated a DataSet named "dsGridRepo rt." In addition,
> that DataSet must contain at least ONE table. If either the DataSet named
> in
> that line of code doesn't exist, OR it has no tables in it, you will get
> the
> exception you describe, as you are referencing an object (either
> dsGridReport or its' table) that doesn't exist in that method or class.
>
> You wouldn't take a carbeurator out of your car, stick it in another car
> of
> another type, and expect it to work, would you?
>
> --
> HTH,
> Kevin Spencer
> .Net Developer
> Microsoft MVP
> Neither a follower
> nor a lender be.
>
> "GaryB" <gb@nospam.co m> wrote in message
> news:OL6bytdzEH A.3120@TK2MSFTN GP12.phx.gbl...[color=green]
>> The following line of code works fine in my code-behind file for an aspx
>> page:
>>
>> Dim HeadingRow As DataRow = dsGridReport.Ta bles(0).NewRow( )
>>
>> But when I transport that same code to a class and run it I get
>>
>> "Object reference not set to an instance of an object"
>>
>> Why?
>> Gary
>>
>>[/color]
>
>[/color]

[Kevin Spencer]

Re: code in class versus aspx page

That wasn't a flame. It was an answer to your question. The last one you'll
get from this Weenie.

Luser. (THAT was a flame)

--
HTH,
Kevin Spencer
..Net Developer
Microsoft MVP
Neither a follower
nor a lender be.

"GaryB" <gb@nospam.co m> wrote in message
news:uP0x6Q#zEH A.3408@tk2msftn gp13.phx.gbl...[color=blue]
> Wow, a flame from a weenie. It's been years.
> Gary :)
>
> "Kevin Spencer" <kspencer@takem pis.com> wrote in message
> news:O57H1FkzEH A.2040@tk2msftn gp13.phx.gbl...[color=green]
> > Okay, I'm trying to calm down from my incredulity, so that I can give[/color][/color]
you[color=blue][color=green]
> > a
> > useful answer.
> >
> > That single line of code is ONLY going to work in a method of a class
> > which
> > has declared AND instantiated a DataSet named "dsGridRepo rt." In[/color][/color]
addition,[color=blue][color=green]
> > that DataSet must contain at least ONE table. If either the DataSet[/color][/color]
named[color=blue][color=green]
> > in
> > that line of code doesn't exist, OR it has no tables in it, you will get
> > the
> > exception you describe, as you are referencing an object (either
> > dsGridReport or its' table) that doesn't exist in that method or class.
> >
> > You wouldn't take a carbeurator out of your car, stick it in another car
> > of
> > another type, and expect it to work, would you?
> >
> > --
> > HTH,
> > Kevin Spencer
> > .Net Developer
> > Microsoft MVP
> > Neither a follower
> > nor a lender be.
> >
> > "GaryB" <gb@nospam.co m> wrote in message
> > news:OL6bytdzEH A.3120@TK2MSFTN GP12.phx.gbl...[color=darkred]
> >> The following line of code works fine in my code-behind file for an[/color][/color][/color]
aspx[color=blue][color=green][color=darkred]
> >> page:
> >>
> >> Dim HeadingRow As DataRow = dsGridReport.Ta bles(0).NewRow( )
> >>
> >> But when I transport that same code to a class and run it I get
> >>
> >> "Object reference not set to an instance of an object"
> >>
> >> Why?
> >> Gary
> >>
> >>[/color]
> >
> >[/color]
>
>[/color]