Comments on: Groovy Sql Closure Examples

By: Rick

Rick — Sat, 21 Mar 2009 18:00:02 +0000

I’m also curious. I’m using groovy.sql.Sql but passing a datasource(dbcp basicdatasource) into the constructor instead of passing passing in connection info through newInstance. I haven’t looked at the groovy Sql source code, but do you know if there are still issues closing connections (returning them to the pool) if using a Datasource instead?

By: Rick

Rick — Sat, 21 Mar 2009 17:50:59 +0000

Nice article. I’m surprised this isn’t implemented by default either (maybe it is now?)

Off topic a bit: I actually found this article while searching for a SqlBuilder… this surprises that one doesn’t exist already? In other words a builder that lets you pass in dynamic sql. For example, you’d pass in several WHERE clause conditions and the fields, and if the fields passed in aren’t null it correctly builds the where clause and prepends the AND or ORs (if needed.) Same thing for IN lists etc when you pass in a collection. Also for ORDER BY (proper comma placements.) You could do similar things for dynamic

I’ll probably go ahead and write one, but just wondering if any of you know of one that someone has written already. Thanks.

I’m new to groovy, but as an idea..

sql.build {
Select( expr: “SELECT * FROM FOOBAR”)
Where{
AND( prop: foo, expr: “animalType = ‘${foo}’”)
AND( prop: bar, expr: “birthDate > ‘${bar}’”)
AND( prop: sizes, in: “animalSize”)
}

}

foo = null, bar = null, sizes =[]:
Select * from foobar

foo = ‘dog’, bar= null, sizes =[]:
Select * from foobar WHERE animalType = ‘dog’

foo = ‘dog’, bar= ‘2009-02-21′, sizes =[4,5,6]:
Select * from foobar WHERE animalType = ‘dog’ AND bithDate > ‘2009-02-21′ AND animalSize in (4,5,6)

By: Bill Coleman

Bill Coleman — Sat, 08 Nov 2008 16:40:25 +0000

Categories really rock. Smalltalk started them, Objective-C has them, and even C# 3.0 has them (Of course, they call them “Extension Methods”)

Categories are a really excellent way to extend an existing framework class without having to resort to subclassing — which is really useful when you don’t always control the creation of instances.

By: John Flinchbaugh

John Flinchbaugh — Mon, 03 Nov 2008 17:15:02 +0000

Using the untyped category selector self has a strange side-effect of adding your newInstance method to *every* class, so I can say String.newInstance(“url”, “login”, “password”, “driver”) {con -> } and your category method will be run. Trying to define the method as newInstance(Sql self, url, login, password, closure) doesn’t seem to add the *static* method.

You seem to have added a static method to Object, but I can’t figure out how to add a static method to just Sql.

Anyone have any ideas?

By: joeygibson

joeygibson — Tue, 21 Oct 2008 14:01:25 +0000

Thanks, Egon. I should have remembered the ? operator. That’s actually what piqued my interest in Groovy. I can’t believe I forgot to include it.

By: Egon

Egon — Tue, 21 Oct 2008 12:18:37 +0000

Great article, I really enjoyed it :-)

If con is null (i.e. Sql.newInstance throws an exception) con.close() will fail.
Just make it save: con?.close()

Likewise the lines
if (closure)
{
closure.call(con)
}
can be shortened to
closure?.call(con)