LINQtoSQL error??

[=?Utf-8?B?UGFvbG8=?=]

I'm getting an error "Object reference not set to an instance of an object."
with line number shown as <### as i try to popuate a DataGridView:

private void btnList_Click(o bject sender, EventArgs e)
{
var act_types = <###
from a in db.Activities
from t in db.Types
where a.Activity_Type == t.Type_Id

orderby a.Activity_Date
select new
{
a.Activity_Date ,
t.Type_Desc,
a.Activity_Dist ance,
a.Activity_Dura tion,
a.Activity_Rout e
};

dgvList.DataSou rce = act_types; // DataGridView
}

This model appears identical to many examples I've seen so what am I missing?

[Jon Skeet [C# MVP]]

Re: LINQtoSQL error??

Paolo <Paolo@discussi ons.microsoft.c omwrote:

I'm getting an error "Object reference not set to an instance of an object."
with line number shown as <### as i try to popuate a DataGridView:
>
private void btnList_Click(o bject sender, EventArgs e)
{
var act_types = <###
from a in db.Activities
from t in db.Types
where a.Activity_Type == t.Type_Id
>
orderby a.Activity_Date
select new
{
a.Activity_Date ,
t.Type_Desc,
a.Activity_Dist ance,
a.Activity_Dura tion,
a.Activity_Rout e
};
>
dgvList.DataSou rce = act_types; // DataGridView
}
>
This model appears identical to many examples I've seen so what am I missing?

Where are you getting db from, and is it definitely non-null?

--
Jon Skeet - <skeet@pobox.co m>
Web site: http://www.pobox.com/~skeet
Blog: http://www.msmvps.com/jon.skeet
C# in Depth: http://csharpindepth.com

[=?Utf-8?B?UGFvbG8=?=]

Re: LINQtoSQL error??

Jon: this is my code so far:

public partial class frmMain : Form
{
DBDataContext db = null; // DBDataContext defined in DBDataContext.c s

public frmMain()
{
InitializeCompo nent();

string cnStr = <connection string// actual string snipped

DBDataContext db = new DBDataContext(c nStr);
}

private void btnList_Click(o bject sender, EventArgs e)
{
var act_types =
from a in db.Activities
from t in db.Types
where a.Activity_Type == t.Type_Id

orderby a.Activity_Date
select new
{
a.Activity_Date ,
t.Type_Desc,
a.Activity_Dist ance,
a.Activity_Dura tion,
a.Activity_Rout e
};
dgvList.DataSou rce = act_types;
}
}

The query worked perfectly when it was part of frmMain
"Jon Skeet [C# MVP]" wrote:

Paolo <Paolo@discussi ons.microsoft.c omwrote:

I'm getting an error "Object reference not set to an instance of an object."
with line number shown as <### as i try to popuate a DataGridView:

private void btnList_Click(o bject sender, EventArgs e)
{
var act_types = <###
from a in db.Activities
from t in db.Types
where a.Activity_Type == t.Type_Id

orderby a.Activity_Date
select new
{
a.Activity_Date ,
t.Type_Desc,
a.Activity_Dist ance,
a.Activity_Dura tion,
a.Activity_Rout e
};

dgvList.DataSou rce = act_types; // DataGridView
}

This model appears identical to many examples I've seen so what am I missing?

>
Where are you getting db from, and is it definitely non-null?
>
--
Jon Skeet - <skeet@pobox.co m>
Web site: http://www.pobox.com/~skeet
Blog: http://www.msmvps.com/jon.skeet
C# in Depth: http://csharpindepth.com
>

[Jon Skeet [C# MVP]]

Re: LINQtoSQL error??

Paolo <Paolo@discussi ons.microsoft.c omwrote:

Jon: this is my code so far:

<snip>

The query worked perfectly when it was part of frmMain

Yes, it would. Look at this line of your constructor:

DBDataContext db = new DBDataContext(c nStr);

That's declaring a new *local variable* called db - it's not setting
the instance variable. Change it to this:

db = new DBDataContext(c nStr);

--
Jon Skeet - <skeet@pobox.co m>
Web site: http://www.pobox.com/~skeet
Blog: http://www.msmvps.com/jon.skeet
C# in Depth: http://csharpindepth.com

[=?Utf-8?B?UGFvbG8=?=]

Re: LINQtoSQL error??

Jon: thanks for pointing that out.

"Jon Skeet [C# MVP]" wrote:

Paolo <Paolo@discussi ons.microsoft.c omwrote:

Jon: this is my code so far:

>
<snip>
>

The query worked perfectly when it was part of frmMain

>
Yes, it would. Look at this line of your constructor:
>
DBDataContext db = new DBDataContext(c nStr);
>
That's declaring a new *local variable* called db - it's not setting
the instance variable. Change it to this:
>
db = new DBDataContext(c nStr);
>
--
Jon Skeet - <skeet@pobox.co m>
Web site: http://www.pobox.com/~skeet
Blog: http://www.msmvps.com/jon.skeet
C# in Depth: http://csharpindepth.com
>