handling dbnulls

[=?Utf-8?B?cm9kY2hhcg==?=]

hey all,

if (DataReader["ParentId"].ToString() != String.Empty)
{
oCategory.ParentId = Convert.ToInt32(DataReader["ParentId"]);
}

ParentId has some null values coming from my database. Is this the correct
way to handle the nulls for this field (or any field for that matter)?

When i debug, inside the immediate window i type:
?DataReader["ParentId"]
{ }

I'm not sure what the 2 braces mean so i added the ToString() and just
checked for " ".

One more thing, about the Convert.ToInt32 is this ok to use? Why isn't there
just a Convert.ToInteger?

thanks,
rodchar

[Jon Skeet [C# MVP]]

On Aug 8, 2:56 pm, rodchar <[e-mail]:

hey all,

if (DataReader["ParentId"].ToString() != String.Empty)
{
oCategory.ParentId = Convert.ToInt32(DataReader["ParentId"]);
}

ParentId has some null values coming from my database. Is this the correct
way to handle the nulls for this field (or any field for that matter)?

It's not a terribly nice way of doing it. I'd use

if (!(DataReader["ParentId"] is DBNull))
{
....
}

One more thing, about the Convert.ToInt32 is this ok to use? Why isn't there
just a Convert.ToInteger?

Because the .NET type name is ToInt32. "ToInteger" would be ambiguous
between Int16, Int32 and Int64 (aka short, int, long in C#).

Jon

[madhatter2647]

if (DataReader["ParentId"] != System.DBNull.Value)

is the correct syntax

the 'two braces' are the identifier for the column in the datareader.

there is no 'convert.tointeger' function because there are many types
of integer representations in the framework. Int16, Int32, Int64 for
signed integers (ie negative and positive numbers) and UInt32, which
is an unsigned integer (only positive numbers)

[Mark Rae [MVP]]

"Jon Skeet [C# MVP]" <sk***@pobox.comwrote in message
news:11**********************@b79g2000hse.googlegr oups.com...

It's not a terribly nice way of doing it. I'd use

if (!(DataReader["ParentId"] is DBNull))
{
...
}

Is there any appreciable difference between the above and:

if (DataReader["ParentId"] != DBNull.Value)
{
....
}
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Jon Skeet [C# MVP]]

On Aug 8, 3:25 pm, "Mark Rae [MVP]" <[e-mail]:

"Jon Skeet [C# MVP]" <[e-mail] in messagenews:11**********************@b79g2000hse.g ooglegroups.com...

It's not a terribly nice way of doing it. I'd use

if (!(DataReader["ParentId"] is DBNull))
{
...
}

Is there any appreciable difference between the above and:

if (DataReader["ParentId"] != DBNull.Value)
{
...

}

Well, when testing in a "positive" way I find

if (DataReader["ParentId"] is DBNull)

more readable than

if (DataReader["ParentId"] == DBNull.Value)

and I was just trying to be consistent with that :)

Jon

[=?Utf-8?B?cm9kY2hhcg==?=]

Thanks everyone for this wealth of knowledge. As always, I appreciate it.
Rod.

"rodchar" wrote:

hey all,

if (DataReader["ParentId"].ToString() != String.Empty)
{
oCategory.ParentId = Convert.ToInt32(DataReader["ParentId"]);
}

ParentId has some null values coming from my database. Is this the correct
way to handle the nulls for this field (or any field for that matter)?

When i debug, inside the immediate window i type:
?DataReader["ParentId"]
{ }

I'm not sure what the 2 braces mean so i added the ToString() and just
checked for " ".

One more thing, about the Convert.ToInt32 is this ok to use? Why isn't there
just a Convert.ToInteger?

thanks,
rodchar

[Mark Rae [MVP]]

"Jon Skeet [C# MVP]" <sk***@pobox.comwrote in message
news:11*********************@b79g2000hse.googlegro ups.com...

Well, when testing in a "positive" way I find

if (DataReader["ParentId"] is DBNull)

more readable than

if (DataReader["ParentId"] == DBNull.Value)

and I was just trying to be consistent with that :)

Fair enough.

BTW, this wasn't a criticism - I was just curious if "is" was more efficient
than "=="...
--
Mark Rae
ASP.NET MVP
http://www.markrae.net

[Jon Skeet [C# MVP]]

Mark Rae [MVP] <ma**@markNOSPAMrae.netwrote:

"Jon Skeet [C# MVP]" <sk***@pobox.comwrote in message
news:11*********************@b79g2000hse.googlegro ups.com...

Well, when testing in a "positive" way I find

if (DataReader["ParentId"] is DBNull)

more readable than

if (DataReader["ParentId"] == DBNull.Value)

and I was just trying to be consistent with that :)

Fair enough.

BTW, this wasn't a criticism - I was just curious if "is" was more efficient
than "=="...

Sure - I wasn't taking it as a criticism.

I've no idea which is more performant to be honest - but I doubt that
it'll be the bottleneck in most code anyway, so I'd go with whatever's
most readable :)

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

[Ignacio Machin \( .NET/ C# MVP \)]

Hi,

"Jon Skeet [C# MVP]" <sk***@pobox.comwrote in message
news:11*********************@b79g2000hse.googlegro ups.com...

On Aug 8, 3:25 pm, "Mark Rae [MVP]" <[e-mail]:

>"Jon Skeet [C# MVP]" <[e-mail] in
messagenews:11**********************@b79g2000hse. googlegroups.com...

It's not a terribly nice way of doing it. I'd use

if (!(DataReader["ParentId"] is DBNull))
{
...
}

Is there any appreciable difference between the above and:

if (DataReader["ParentId"] != DBNull.Value)
{
...

}

Well, when testing in a "positive" way I find

if (DataReader["ParentId"] is DBNull)

more readable than

if (DataReader["ParentId"] == DBNull.Value)

and I was just trying to be consistent with that :)

I like the latter more :)

It should be that I live in the tropics and you live in England :)