How would I shorten this If... Else... statement to check the state of a Date?

Question

I am a C# programmer but dabbling in VB.Net because everybody else in my team uses it. In the interests of professional development I would like to shrink the following If... Else... statement.

If cmd.Parameters("@whenUpdated").Equals(DBNull.Value) Then
    item.WhenUpdated = Nothing
Else
    item.WhenUpdated = cmd.Parameters("@whenUpdated").Value
End If

I appreciate examples are already available however I can not get it working for this specific case.

Cheers, Ian.

While not very obvious, this is almost a duplicate of http://stackoverflow.com/questions/576431/is-there-a-conditional-ternary-operator-in-vb-net — Jørn Schou-Rode, Apr 02 '10 at 22:42
Thank you I saw that question but didn't understand how to apply it in this situation. I see you have voted to close. That's fine I have the answer I need. — Ian Roke, Apr 02 '10 at 22:43
@Mark it is I am working very late I apologise I will turn it round. — Ian Roke, Apr 02 '10 at 22:44
@Ian: I am sorry about that. The "I am a C# programmer" preface of your question made me conclude that you probably knew about the `?:` syntax and wanted something similar. — Jørn Schou-Rode, Apr 02 '10 at 22:45
Thanks @Cresults I am finding it very interesting and not dissimilar to VBA! :-D — Ian Roke, Apr 02 '10 at 22:46
@Jørn, sure I know how to do it in C# but for some reason it wasn't directly copying over to VB.Net. As I have said I am working very late I need to sleep... or get coffee! 8-) — Ian Roke, Apr 02 '10 at 22:48

score 6 · Accepted Answer · answered Apr 02 '10 at 22:40

6

Use If as a function rather than a statement:

item.WhenUpdated = If(cmd.Parameters("@whenUpdated").Equals(DBNull.Value), cmd.Parameters("@whenUpdated").Value, Nothing)

answered Apr 02 '10 at 22:40

Dan Story

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You still have to put this twice `cmd.Parameters("@whenUpdated").Value`. Why not write a DBNull2Nothing function? Make it much shorter & self documenting? – MarkJ Apr 03 '10 at 17:43

score 3 · Answer 2 · answered Apr 02 '10 at 22:40

3

Similar to the ternary operator in C#, VB has the IIF function.

item.WhenUpdated = IIF(cmd.Parameters("@whenUpdated").Equals(DBNull.Value),
                            cmd.Parameters("@whenUpdated").Value, 
                            Nothing)

If the first argument (the boolean expression) evaluates to true, then the second argument is returned from the function. If the first argument is false, then the third argument is returned.

answered Apr 02 '10 at 22:40

womp

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The IIf function doesn't short-circuit and returns type Object, which must be cast. As long as you're using VB2008, it's better to use the new If ternary operator instead. – Dan Story Apr 02 '10 at 22:43
Good to know. I dropped VB a few years back and haven't done much with it since. – womp Apr 02 '10 at 22:45
Some people have all the luck! – Ian Roke Apr 02 '10 at 22:51

score 2 · Answer 3 · answered Apr 02 '10 at 22:40

2

item.WhenUpdated = Nothing
If cmd.Parameters("@whenUpdated").Equals(DBNull.Value) Then
    item.WhenUpdated = cmd.Parameters("@whenUpdated").Value
End If

Only 1 line, but still shorter.

The IF function is definitely the shortest, but not the most readable.

answered Apr 02 '10 at 22:40

Dustin Laine

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You could also put the =Nothing at the declaration, so Dim WhenUpdated as Date = Nothing. That'd save another line :-) – CResults Apr 02 '10 at 22:46
I can't do that @CResults as it is a data object. ;-) – Ian Roke Apr 02 '10 at 22:48

score 0 · Answer 4 · answered Apr 02 '10 at 22:41

0

One less line

item.WhenUpdated = Nothing
If cmd.Parameters("@whenUpdated").Equals(DBNull.Value) Then
    item.WhenUpdated = cmd.Parameters("@whenUpdated").Value
End If

answered Apr 02 '10 at 22:41

Samuel Carrijo

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score 0 · Answer 5 · answered Apr 02 '10 at 22:44

0

Use the operator If(...) if you want short-circuiting behavior.

Use the function IIf(...) if you don't want short-circuiting behavior.

answered Apr 02 '10 at 22:44

Chris

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How would I shorten this If... Else... statement to check the state of a Date?

5 Answers5