Testing for DBNulls

[Fred Chateau]

I can't seem to find a test for DBNulls. Whatever I try doesn't work.

for (int x = 0; x < dataSet.Identit y.Rows.Count; x++)
{
DataRow dataRow = dataSet.Tables["POI_Entity "].NewRow();

if (!dataSet.Ident ity[x].Chain_ID.Equal s(DBNull.Value) )
dataRow["Chain_Id"] = dataSet.Identit y[x].Chain_ID;
else
dataRow["Chain_Id"] = 0;

dataSet.Tables["POI_Entity "].Rows.Add(dataR ow);
}

I've also tried

(!Convert.IsDBN ull(dataSet.Ide ntity[x].Chain_ID)

That doesn't work either.

--
Regards,

Fred Chateau
http://hotelmotelnow.com

[Nicholas Paldino [.NET/C# MVP]]

Fred,

Have you set a point in the debugger and looked at what the value of:

dataSet.Identit y[x].Chain_ID

Actually is?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:e3******** ******@TK2MSFTN GP04.phx.gbl...

>I can't seem to find a test for DBNulls. Whatever I try doesn't work.

for (int x = 0; x < dataSet.Identit y.Rows.Count; x++)
{
DataRow dataRow = dataSet.Tables["POI_Entity "].NewRow();

if (!dataSet.Ident ity[x].Chain_ID.Equal s(DBNull.Value) )
dataRow["Chain_Id"] = dataSet.Identit y[x].Chain_ID;
else
dataRow["Chain_Id"] = 0;

dataSet.Tables["POI_Entity "].Rows.Add(dataR ow);
}

I've also tried

(!Convert.IsDBN ull(dataSet.Ide ntity[x].Chain_ID)

That doesn't work either.

--
Regards,

Fred Chateau
http://hotelmotelnow.com

[macleod]

try
if (dataSet.Identi ty[x].Chain_ID != null)
"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:e3******** ******@TK2MSFTN GP04.phx.gbl...

>I can't seem to find a test for DBNulls. Whatever I try doesn't work.

for (int x = 0; x < dataSet.Identit y.Rows.Count; x++)
{
DataRow dataRow = dataSet.Tables["POI_Entity "].NewRow();

if (!dataSet.Ident ity[x].Chain_ID.Equal s(DBNull.Value) )
dataRow["Chain_Id"] = dataSet.Identit y[x].Chain_ID;
else
dataRow["Chain_Id"] = 0;

dataSet.Tables["POI_Entity "].Rows.Add(dataR ow);
}

I've also tried

(!Convert.IsDBN ull(dataSet.Ide ntity[x].Chain_ID)

That doesn't work either.

--
Regards,

Fred Chateau
http://hotelmotelnow.com

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

Fred Chateau wrote:

I can't seem to find a test for DBNulls. Whatever I try doesn't work.

for (int x = 0; x < dataSet.Identit y.Rows.Count; x++)
{
DataRow dataRow = dataSet.Tables["POI_Entity "].NewRow();

if (!dataSet.Ident ity[x].Chain_ID.Equal s(DBNull.Value) )
dataRow["Chain_Id"] = dataSet.Identit y[x].Chain_ID;
else
dataRow["Chain_Id"] = 0;

dataSet.Tables["POI_Entity "].Rows.Add(dataR ow);
}

I've also tried

(!Convert.IsDBN ull(dataSet.Ide ntity[x].Chain_ID)

That doesn't work either.

What kind of object does your variable "dataSet" reference?

If you have a DataRow, it has the method IsNull that you can use to
check for DbNull values.

If you have a data reader, it has the method IsDbNull that you can use
to check for DbNull values.

--
Göran Andersson
_____
http://www.guffa.com

[Fred Chateau]

Well, I can't believe I found it but I did. I had to edit the code generated
by XSD.

[System.Diagnost ics.DebuggerNon UserCodeAttribu te()]
public string Chain_ID {
get {
try {
if (!Convert.IsDBN ull(this[this.tableIdent ity.Chain_IDCol umn])) <--
Added code
return ((string) (this[this.tableIdent ity.Chain_IDCol umn]));
else
return "0";
<-- Added code
}
catch (System.Invalid CastException e) {
throw new System.Data.Str ongTypingExcept ion("The value for column
\'Chain_ID\' in table \'Identity\' is DBNull.", e);
}
}
set {
this[this.tableIdent ity.Chain_IDCol umn] = value;
}
}

--
Regards,

Fred Chateau
http://hotelmotelnow.com
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard .caspershouse.c omwrote in
message news:uh******** ******@TK2MSFTN GP04.phx.gbl...

Fred,

Have you set a point in the debugger and looked at what the value of:

dataSet.Identit y[x].Chain_ID

Actually is?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:e3******** ******@TK2MSFTN GP04.phx.gbl...

>>I can't seem to find a test for DBNulls. Whatever I try doesn't work.

for (int x = 0; x < dataSet.Identit y.Rows.Count; x++)
{
DataRow dataRow = dataSet.Tables["POI_Entity "].NewRow();

if (!dataSet.Ident ity[x].Chain_ID.Equal s(DBNull.Value) )
dataRow["Chain_Id"] = dataSet.Identit y[x].Chain_ID;
else
dataRow["Chain_Id"] = 0;

dataSet.Tabl es["POI_Entity "].Rows.Add(dataR ow);
}

I've also tried

(!Convert.IsDB Null(dataSet.Id entity[x].Chain_ID)

That doesn't work either.

--
Regards,

Fred Chateau
http://hotelmotelnow.com

[Nicholas Paldino [.NET/C# MVP]]

Fred,

Well, I wouldn't do that. What I was recommending was to determine what
the value that was being returned was through the debugger in your program,
and then using that knowledge to change the code.

Generally, I wouldn't change the designer code, because it will not
respect your changes if you make changes through the designer.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:uC******** ******@TK2MSFTN GP02.phx.gbl...

Well, I can't believe I found it but I did. I had to edit the code
generated by XSD.

[System.Diagnost ics.DebuggerNon UserCodeAttribu te()]
public string Chain_ID {
get {
try {
if (!Convert.IsDBN ull(this[this.tableIdent ity.Chain_IDCol umn])) <--
Added code
return ((string) (this[this.tableIdent ity.Chain_IDCol umn]));
else
return "0"; <-- Added code
}
catch (System.Invalid CastException e) {
throw new System.Data.Str ongTypingExcept ion("The value for column
\'Chain_ID\' in table \'Identity\' is DBNull.", e);
}
}
set {
this[this.tableIdent ity.Chain_IDCol umn] = value;
}
}

--
Regards,

Fred Chateau
http://hotelmotelnow.com
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard .caspershouse.c omwrote
in message news:uh******** ******@TK2MSFTN GP04.phx.gbl...

>Fred,

Have you set a point in the debugger and looked at what the value of:

dataSet.Identi ty[x].Chain_ID

Actually is?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:e3******* *******@TK2MSFT NGP04.phx.gbl.. .

>>>I can't seem to find a test for DBNulls. Whatever I try doesn't work.

for (int x = 0; x < dataSet.Identit y.Rows.Count; x++)
{
DataRow dataRow = dataSet.Tables["POI_Entity "].NewRow();

if (!dataSet.Ident ity[x].Chain_ID.Equal s(DBNull.Value) )
dataRow["Chain_Id"] = dataSet.Identit y[x].Chain_ID;
else
dataRow["Chain_Id"] = 0;

dataSet.Table s["POI_Entity "].Rows.Add(dataR ow);
}

I've also tried

(!Convert.IsD BNull(dataSet.I dentity[x].Chain_ID)

That doesn't work either.

--
Regards,

Fred Chateau
http://hotelmotelnow.com

[Fred Chateau]

I'm not sure how I could do anything else. It tries to cast the XML Node
value to a string and if the cast fails, it throws an Invalid Cast
Exception, then sends out the message: The value for column <columnNamein
table <tableNameis DBNull.

It should pass the DBNull along so I can test for it, but it never gets that
far. You can't modify your code when you don't even have access to the
variable.

Do you think there's a way to catch the exception? Even if there is, isn't
that bad practice to use an exception to determine a decision branch in the
code?

--
Regards,

Fred Chateau
http://hotelmotelnow.com
--
Regards,

Fred Chateau
http://hotelmotelnow.com

"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard .caspershouse.c omwrote in
message news:e7******** ******@TK2MSFTN GP03.phx.gbl...

Fred,

Well, I wouldn't do that. What I was recommending was to determine
what the value that was being returned was through the debugger in your
program, and then using that knowledge to change the code.

Generally, I wouldn't change the designer code, because it will not
respect your changes if you make changes through the designer.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:uC******** ******@TK2MSFTN GP02.phx.gbl...

>Well, I can't believe I found it but I did. I had to edit the code
generated by XSD.

[System.Diagnost ics.DebuggerNon UserCodeAttribu te()]
public string Chain_ID {
get {
try {
if (!Convert.IsDBN ull(this[this.tableIdent ity.Chain_IDCol umn])) <--
Added code
return ((string) (this[this.tableIdent ity.Chain_IDCol umn]));
else
return "0"; <-- Added code
}
catch (System.Invalid CastException e) {
throw new System.Data.Str ongTypingExcept ion("The value for column
\'Chain_ID\' in table \'Identity\' is DBNull.", e);
}
}
set {
this[this.tableIdent ity.Chain_IDCol umn] = value;
}
}

--
Regards,

Fred Chateau
http://hotelmotelnow.com
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard .caspershouse.c omwrote
in message news:uh******** ******@TK2MSFTN GP04.phx.gbl...

>>Fred,

Have you set a point in the debugger and looked at what the value of:

dataSet.Ident ity[x].Chain_ID

Actually is?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:e3****** ********@TK2MSF TNGP04.phx.gbl. ..
I can't seem to find a test for DBNulls. Whatever I try doesn't work.

for (int x = 0; x < dataSet.Identit y.Rows.Count; x++)
{
DataRow dataRow = dataSet.Tables["POI_Entity "].NewRow();

if (!dataSet.Ident ity[x].Chain_ID.Equal s(DBNull.Value) )
dataRow["Chain_Id"] = dataSet.Identit y[x].Chain_ID;
else
dataRow["Chain_Id"] = 0;

dataSet.Tabl es["POI_Entity "].Rows.Add(dataR ow);
}

I've also tried

(!Convert.Is DBNull(dataSet. Identity[x].Chain_ID)

That doesn't work either.

--
Regards,

Fred Chateau
http://hotelmotelnow.com

[Nicholas Paldino [.NET/C# MVP]]

Fred,

This is a typed data set, right? You should be able to highlight the
column in the designer and indicate that you want it to return DBNull when
null is encountered for that column.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:u0******** ******@TK2MSFTN GP03.phx.gbl...

I'm not sure how I could do anything else. It tries to cast the XML Node
value to a string and if the cast fails, it throws an Invalid Cast
Exception, then sends out the message: The value for column <columnName>
in table <tableNameis DBNull.

It should pass the DBNull along so I can test for it, but it never gets
that far. You can't modify your code when you don't even have access to
the variable.

Do you think there's a way to catch the exception? Even if there is, isn't
that bad practice to use an exception to determine a decision branch in
the code?

--
Regards,

Fred Chateau
http://hotelmotelnow.com
--
Regards,

Fred Chateau
http://hotelmotelnow.com

"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard .caspershouse.c omwrote
in message news:e7******** ******@TK2MSFTN GP03.phx.gbl...

>Fred,

Well, I wouldn't do that. What I was recommending was to determine
what the value that was being returned was through the debugger in your
program, and then using that knowledge to change the code.

Generally, I wouldn't change the designer code, because it will not
respect your changes if you make changes through the designer.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:uC******* *******@TK2MSFT NGP02.phx.gbl.. .

>>Well, I can't believe I found it but I did. I had to edit the code
generated by XSD.

[System.Diagnost ics.DebuggerNon UserCodeAttribu te()]
public string Chain_ID {
get {
try {
if (!Convert.IsDBN ull(this[this.tableIdent ity.Chain_IDCol umn])) <--
Added code
return ((string) (this[this.tableIdent ity.Chain_IDCol umn]));
else
return "0"; <-- Added code
}
catch (System.Invalid CastException e) {
throw new System.Data.Str ongTypingExcept ion("The value for column
\'Chain_ID\ ' in table \'Identity\' is DBNull.", e);
}
}
set {
this[this.tableIdent ity.Chain_IDCol umn] = value;
}
}

--
Regards,

Fred Chateau
http://hotelmotelnow.com
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard .caspershouse.c omwrote
in message news:uh******** ******@TK2MSFTN GP04.phx.gbl...
Fred,

Have you set a point in the debugger and looked at what the value
of:

dataSet.Iden tity[x].Chain_ID

Actually is?
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:e3***** *********@TK2MS FTNGP04.phx.gbl ...
>I can't seem to find a test for DBNulls. Whatever I try doesn't work.
>
for (int x = 0; x < dataSet.Identit y.Rows.Count; x++)
{
DataRow dataRow = dataSet.Tables["POI_Entity "].NewRow();
>
if (!dataSet.Ident ity[x].Chain_ID.Equal s(DBNull.Value) )
dataRow["Chain_Id"] = dataSet.Identit y[x].Chain_ID;
else
dataRow["Chain_Id"] = 0;
>
dataSet.Tab les["POI_Entity "].Rows.Add(dataR ow);
}
>
I've also tried
>
(!Convert.I sDBNull(dataSet .Identity[x].Chain_ID)
>
That doesn't work either.
>
--
Regards,
>
Fred Chateau
http://hotelmotelnow.com
>

[Larry Smith]

for (int x = 0; x < dataSet.Identit y.Rows.Count; x++)

{
DataRow dataRow = dataSet.Tables["POI_Entity "].NewRow();

if (!dataSet.Ident ity[x].Chain_ID.Equal s(DBNull.Value) )
dataRow["Chain_Id"] = dataSet.Identit y[x].Chain_ID;
else
dataRow["Chain_Id"] = 0;

dataSet.Tables["POI_Entity "].Rows.Add(dataR ow);
}

I've also tried

(!Convert.IsDBN ull(dataSet.Ide ntity[x].Chain_ID)

That doesn't work either.

foreach (IdentityRow identtyRow in dataSet.Identit y)
{

if (identityRow.Is Chain_IDNull)
{
}
else
{
}

dataSet.POI_Ent ity.New
}

[Fred Chateau]

Well, that worked too.

The choices are empty, null and throw exception. I set the value to return
an empty string and then tested for the empty string.

Thanks again, Nicholas.

--
Regards,

Fred Chateau
http://hotelmotelnow.com

"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard .caspershouse.c omwrote in
message news:ee******** ******@TK2MSFTN GP02.phx.gbl...

Fred,

This is a typed data set, right? You should be able to highlight the
column in the designer and indicate that you want it to return DBNull when
null is encountered for that column.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:u0******** ******@TK2MSFTN GP03.phx.gbl...

>I'm not sure how I could do anything else. It tries to cast the XML Node
value to a string and if the cast fails, it throws an Invalid Cast
Exception, then sends out the message: The value for column <columnName>
in table <tableNameis DBNull.

It should pass the DBNull along so I can test for it, but it never gets
that far. You can't modify your code when you don't even have access to
the variable.

Do you think there's a way to catch the exception? Even if there is,
isn't that bad practice to use an exception to determine a decision
branch in the code?

--
Regards,

Fred Chateau
http://hotelmotelnow.com
--
Regards,

Fred Chateau
http://hotelmotelnow.com

"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard .caspershouse.c omwrote
in message news:e7******** ******@TK2MSFTN GP03.phx.gbl...

>>Fred,

Well, I wouldn't do that. What I was recommending was to determine
what the value that was being returned was through the debugger in your
program, and then using that knowledge to change the code.

Generally, I wouldn't change the designer code, because it will not
respect your changes if you make changes through the designer.
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m

"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:uC****** ********@TK2MSF TNGP02.phx.gbl. ..
Well, I can't believe I found it but I did. I had to edit the code
generated by XSD.

[System.Diagnost ics.DebuggerNon UserCodeAttribu te()]
public string Chain_ID {
get {
try {
if (!Convert.IsDBN ull(this[this.tableIdent ity.Chain_IDCol umn])) <--
Added code
return ((string) (this[this.tableIdent ity.Chain_IDCol umn]));
else
return "0"; <-- Added code
}
catch (System.Invalid CastException e) {
throw new System.Data.Str ongTypingExcept ion("The value for column
\'Chain_ID \' in table \'Identity\' is DBNull.", e);
}
}
set {
this[this.tableIdent ity.Chain_IDCol umn] = value;
}
}

--
Regards,

Fred Chateau
http://hotelmotelnow.com
"Nicholas Paldino [.NET/C# MVP]" <mv*@spam.guard .caspershouse.c om>
wrote in message news:uh******** ******@TK2MSFTN GP04.phx.gbl...
Fred,
>
Have you set a point in the debugger and looked at what the value
of:
>
dataSet.Ide ntity[x].Chain_ID
>
Actually is?
>
>
--
- Nicholas Paldino [.NET/C# MVP]
- mv*@spam.guard. caspershouse.co m
>
"Fred Chateau" <we*******@hote lmotelnow.comwr ote in message
news:e3**** **********@TK2M SFTNGP04.phx.gb l...
>>I can't seem to find a test for DBNulls. Whatever I try doesn't work.
>>
>for (int x = 0; x < dataSet.Identit y.Rows.Count; x++)
>{
> DataRow dataRow = dataSet.Tables["POI_Entity "].NewRow();
>>
> if (!dataSet.Ident ity[x].Chain_ID.Equal s(DBNull.Value) )
> dataRow["Chain_Id"] = dataSet.Identit y[x].Chain_ID;
> else
> dataRow["Chain_Id"] = 0;
>>
>dataSet.Ta bles["POI_Entity "].Rows.Add(dataR ow);
>}
>>
>I've also tried
>>
>(!Convert. IsDBNull(dataSe t.Identity[x].Chain_ID)
>>
>That doesn't work either.
>>
>--
>Regards,
>>
>Fred Chateau
>http://hotelmotelnow.com
>>
>
>