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NullReference Exception on DataTable.Rows.AddI would just like to advice on how to fix a problem I'm having in adding a new row to a DataTable. Anyway, my problem is that this code always gives me the dreaded "object reference not set to an instance" exception: [C#] (WinForms) DataRow row; row = DataSet.Tables[0].NewRow(); // set row column values here DataSet.Tables[0].Rows.Add(row); //<< exception on this line I've check on the values for DataSet, Tables[0], Tables[0].Rows and row... They all have valid values, so how come the exception is thrown? I've also tried something like: DataRow row; DataTable table = DataSet.Tables[0]; row = table.NewRow(); //set column values here table.Rows.Add(row) //<< exception still gets thrown here I'm using Visual Studio 2003 with .NET framework sp1 installed on Windows XP professional with SP2... The funny thing is that within the same event, but under the code for a different "case" block, i have a similar set of code for a different table within the same dataset but the exception doesn't get thrown during the Rows.Add portion. One more thing, this wasn't a problem when the .NETFX SP1 wasn't installed yet. I would really appreciate any insight anyone can give on this, we really need to install SP1, because of certain fixes that it introduced. I'm thinking maybe some of the Post-SP1 "hotfixes" might address this problem, but I don't know which. BTW, there's someone else who encountered a similar error, he's already posted his problem on several forums last October 2004 and there's no reply to his post, I'm just not sure if he has SP1 installed. Links to his posts are [URL=http://www.techietwo.com/detail-6334024.html]http://www.techietwo.com/detail-6334024.html[/URL] [URL=http://www.devnewsgroups.net/group/microsoft.public.dotnet.framework/topic2591.aspx]http://www.devnewsgroups.net/group/microsoft.public.dotnet.framework/topic2591.aspx[/URL] you can also try searching for "datatable.insertrow object reference" on google groups, it's one of the 2 posts that will be shown in the search results. TIA. raist Is "DataSet" in your code an instance of DataSet object?
I mean, you must have something like DataSet DataSet=new DataSet(); prior to you code snippet for adding rows. I do not even want to try if this code works or not, just want to ask why you have a variable that is the same as a class name. It is bad practice, even it works (I doubt). I would: DataSet myDataSet=new DataSet() //Add or create table in it //Then DataRow row=myDataSet.Tables[0].NewRow(); So, it is clear "myDataSet" is an instance of DataSet object Show quote "Raistlin" <Raist***@discussions.microsoft.com> wrote in message news:69B7FD3D-E9DA-4C08-AF88-A7DED51E3785@microsoft.com... > Hi, > > I would just like to advice on how to fix a problem I'm having in adding a > new row to a DataTable. > > Anyway, my problem is that this code always gives me the dreaded "object > reference not set to an instance" exception: > > [C#] (WinForms) > > DataRow row; > > row = DataSet.Tables[0].NewRow(); > // set row column values here > DataSet.Tables[0].Rows.Add(row); //<< exception on this line > > I've check on the values for DataSet, Tables[0], Tables[0].Rows and row... > They all have valid values, so how come the exception is thrown? > > I've also tried something like: > > DataRow row; > DataTable table = DataSet.Tables[0]; > row = table.NewRow(); > //set column values here > table.Rows.Add(row) //<< exception still gets thrown here > > I'm using Visual Studio 2003 with .NET framework sp1 installed on Windows > XP > professional with SP2... > > The funny thing is that within the same event, but under the code for a > different "case" block, i have a similar set of code for a different table > within the same dataset but the exception doesn't get thrown during the > Rows.Add portion. > > One more thing, this wasn't a problem when the .NETFX SP1 wasn't installed > yet. > > I would really appreciate any insight anyone can give on this, we really > need to install SP1, because of certain fixes that it introduced. > > I'm thinking maybe some of the Post-SP1 "hotfixes" might address this > problem, but I don't know which. > > BTW, there's someone else who encountered a similar error, he's already > posted his problem on several forums last October 2004 and there's no > reply > to his post, I'm just not sure if he has SP1 installed. Links to his posts > are > [URL=http://www.techietwo.com/detail-6334024.html]http://www.techietwo.com/detail-6334024.html[/URL] > [URL=http://www.devnewsgroups.net/group/microsoft.public.dotnet.framework/topic2591.aspx]http://www.devnewsgroups.net/group/microsoft.public.dotnet.framework/topic2591.aspx[/URL] > > you can also try searching for "datatable.insertrow object reference" on > google groups, it's one of the 2 posts that will be shown in the search > results. > > > TIA. > > raist > Sorry for the misunderstanding,
I just used the word "DataSet" as an example. In my code it's called "DataBind". The problem isn't because of a DataSet variable named "DataSet". Thanks. raistlin Just an update:
When I change the code from: DataRow row; row = dataSet.Tables[0].NewRow(); dataSet.Tables[0].Rows.Add(row); //<< code throws NullReferenceException here to: DataRow row; row = dataSet.Tables[0].NewRow(); try { dataSet.Tables[0].Rows.Add(row); } catch (NullReferenceException) { dataSet.Tables[0].Rows.Add(row); } The application behaves "normally", although the NullReferenceException still occurs. Is there a way to actually detect "what" is "actually" causing the NullReferenceException? Because, although it "works", this "fix" still isn't "right". Thanks in advance. Show quote "Raistlin" wrote: > Hi, > > I would just like to advice on how to fix a problem I'm having in adding a > new row to a DataTable. > > Anyway, my problem is that this code always gives me the dreaded "object > reference not set to an instance" exception: > > [C#] (WinForms) > > DataRow row; > > row = DataSet.Tables[0].NewRow(); > // set row column values here > DataSet.Tables[0].Rows.Add(row); //<< exception on this line > > I've check on the values for DataSet, Tables[0], Tables[0].Rows and row... > They all have valid values, so how come the exception is thrown? > > I've also tried something like: > > DataRow row; > DataTable table = DataSet.Tables[0]; > row = table.NewRow(); > //set column values here > table.Rows.Add(row) //<< exception still gets thrown here > > I'm using Visual Studio 2003 with .NET framework sp1 installed on Windows XP > professional with SP2... > > The funny thing is that within the same event, but under the code for a > different "case" block, i have a similar set of code for a different table > within the same dataset but the exception doesn't get thrown during the > Rows.Add portion. > > One more thing, this wasn't a problem when the .NETFX SP1 wasn't installed > yet. > > I would really appreciate any insight anyone can give on this, we really > need to install SP1, because of certain fixes that it introduced. > > I'm thinking maybe some of the Post-SP1 "hotfixes" might address this > problem, but I don't know which. > > BTW, there's someone else who encountered a similar error, he's already > posted his problem on several forums last October 2004 and there's no reply > to his post, I'm just not sure if he has SP1 installed. Links to his posts > are > [URL=http://www.techietwo.com/detail-6334024.html]http://www.techietwo.com/detail-6334024.html[/URL] > [URL=http://www.devnewsgroups.net/group/microsoft.public.dotnet.framework/topic2591.aspx]http://www.devnewsgroups.net/group/microsoft.public.dotnet.framework/topic2591.aspx[/URL] > > you can also try searching for "datatable.insertrow object reference" on > google groups, it's one of the 2 posts that will be shown in the search > results. > > > TIA. > > raist >  |
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