28 Nov
2014
28 Nov
'14
12:59 a.m.
What's the preferred way to deal with errors occuring in Java components? Is it OK to
throw an exception from within the component, and can this be caught within the Velocity
or Groovy code that calls it?
28 Nov
28 Nov
9:34 a.m.
On 28 Nov 2014 at 01:00:37, Bryn Jeffries
(bryn.jeffries@sydney.edu.au(mailto:bryn.jeffries@sydney.edu.au)) wrote:
What's the preferred way to deal with errors
occuring in Java components? Is it OK to throw an exception from within the component,
yes
and can this be caught within the Velocity or Groovy
code that calls it?
errors are automatically caught in the script macros ({{velocity}}, {{groovy}}, etc).
Thanks
-Vincent
9:17 p.m.
Said Vincent:
OK, looks like Groovy has explicit try/catch
(http://groovy.codehaus.org/JN3035-Exceptions). I couldn't see anything about Velocity
catching exceptions (only about Velocity throwing exceptions -
http://velocity.apache.org/engine/devel/developer-guide.html#exceptions).
So if I have a component that I call from velocity with $mycomponent.foo() and the method
throws an exception (IOException, for instance), can I control what the Velocity script
does about this?
and can this
be caught within the Velocity or Groovy code that calls it?
errors are automatically caught in the script macros ({{velocity}}, {{groovy}}, etc).
9:30 p.m.
On Fri, Nov 28, 2014 at 9:17 PM, Bryn Jeffries
<bryn.jeffries(a)sydney.edu.au> wrote:
Said Vincent:
OK, looks like Groovy has explicit try/catch
(http://groovy.codehaus.org/JN3035-Exceptions). I couldn't see anything about Velocity
catching exceptions (only about Velocity throwing exceptions -
http://velocity.apache.org/engine/devel/developer-guide.html#exceptions).
Yes there is nothing in standard Velocity but XWiki add some tools to
Velocity and among other things some try/catching support, see
http://extensions.xwiki.org/xwiki/bin/view/Extension/Velocity+Module#HVeloc….
What Vincent meant by automatically caught is that you get to see the
error in the error where you have put the {{velocity}} macro, it does
not break the whole page.
and can
this be caught within the Velocity or Groovy code that calls it?
errors are automatically caught in the script macros ({{velocity}}, {{groovy}}, etc).
So if I have a component that I call from velocity with $mycomponent.foo() and the method
throws an exception (IOException, for instance), can I control what the Velocity script
does about this?
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Thomas Mortagne
29 Nov
29 Nov
10 a.m.
I misunderstood what you wanted. I thought you wanted to know what the {{velocity}} or
{{groovy}} macros would display. They automatically catch exceptions. Now it seems your
question is different and you wish to be able to catch exceptions in your own script.
XWiki offers a scripting API for all Java API (for example when you call $services.xxx).
It’s not the same API as the Java API. And our rule is in general to not throw Exceptions
but instead to return null when there are problems. The main reason was because of
Velocity indeed.
That said, we’ve recently introduced a way to catch exceptions in Velocity:
http://www.xwiki.org/xwiki/bin/view/ReleaseNotes/ReleaseNotesXWiki63#HAbili…
Hope it helps
-Vincent
On 28 Nov 2014 at 21:18:56, Bryn Jeffries
(bryn.jeffries@sydney.edu.au(mailto:bryn.jeffries@sydney.edu.au)) wrote:
Said Vincent:
OK, looks like Groovy has explicit try/catch
(http://groovy.codehaus.org/JN3035-Exceptions). I couldn't see anything about Velocity
catching exceptions (only about Velocity throwing exceptions -
http://velocity.apache.org/engine/devel/developer-guide.html#exceptions).
So if I have a component that I call from velocity with $mycomponent.foo() and the method
throws an exception (IOException, for instance), can I control what the Velocity script
does about this?
and can
this be caught within the Velocity or Groovy code that calls it?
errors are automatically caught in the script macros ({{velocity}}, {{groovy}}, etc).
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4 comments
3 participants
participants (3)
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Bryn Jeffries -
Thomas Mortagne -
vincent＠massol.net