Object-Type Attribute Value Evaluation

[brettryan]

Object type attributes such as the <menu /> implementation may now implement o.a.t.awareness.ExpressionAware which causes #evaluateExpressions(AttributeEvaluator,Request) to be called during attribute evaluation.

It is up to the implementation to handle evaluation using the supplied evaluator.

Implementors may return any object type or a duplicated of itself with expressions replaced which will be used for rendering within the view model.

[michaelsembwever]

discussion on the need for this is in https://permalink.gmane.org/gmane.comp.apache.tiles.devel/743 and https://permalink.gmane.org/gmane.comp.apache.tiles.devel/744

particularly because it introduces changes outside of tiles-compat and we want to think carefully around that.

[brettryan]

Hey thanks mck, I really am silly and should have signed up to tiles-dev but the thought didn't even cross my mind, sorry for that.

Interestingly though I did ask on the users mailing list before I submitted my solution if there was a way to get <item> to evaluate expressions, I requested if there was a newer alternative, the response was actually from yourself to look at the code as it's fairly simple :)

Anyway, I think your solution would work, I never knew you could nest lists, there's little examples of this except now reading the DTD I see this is supported.

It does seem to not work however, when I add use an expression, i.e. <add-attribute expression="${customer.id}"/> attempts to render the attribute fail with a NPE, however if I use value it renders, but unevaluated.

I'll mention this on the dev mailing list.

[michaelsembwever]

Interestingly though I did ask on the users mailing list before I
submitted my solution if there was a way to get to evaluate
expressions, I requested if there was a newer alternative, the response was
actually from yourself to look at the code as it's fairly simple :)

Yeah my apologies for that Brett. I didn't catch it, at least too late once
Nick raised concerns about the improvements you need (in the PR) changing
code beyond tiles-compat.

It does seem to not work however, when I add use an expression, i.e.
attempts to render the
attribute fail with a NPE, however if I use value it renders, but
unevaluated.

If this is a bug then a pull request there will of course be of great
value. Things would be more on the tiles-3.0 way of doing things :-)

~mck

[brettryan]

On 8 Jul 2015, at 21:25, mck [email protected] wrote:

Interestingly though I did ask on the users mailing list before I
submitted my solution if there was a way to get to evaluate
expressions, I requested if there was a newer alternative, the response was
actually from yourself to look at the code as it's fairly simple :)

Yeah my apologies for that Brett. I didn't catch it, at least too late once
Nick raised concerns about the improvements you need (in the PR) changing
code beyond tiles-compat.

It's cool, I'm happy to help where I'm able. If I can I really would like to help with documentation of tiles. It could be me but sometimes I find it a tiny bit sparse :)

It does seem to not work however, when I add use an expression, i.e.
attempts to render the
attribute fail with a NPE, however if I use value it renders, but
unevaluated.

If this is a bug then a pull request there will of course be of great
value. Things would be more on the tiles-3.0 way of doing things :-)

Thanks, I'm just trying to track down the bug, my stacktraces are being swallowed by something else so need to setup a test project to figure out what's going on. My brain's fried at the moment so will look at it later, it seems most of what I can see is pointing at tiles-request so will need to look harder.

[michaelsembwever]

On 8 July 2015 at 13:39, Brett Ryan [email protected] wrote:

It's cool, I'm happy to help where I'm able. If I can I really would like
to help with documentation of tiles. It could be me but sometimes I find it
a tiny bit sparse :)

Yeah that would be hugely appreciated. Often documentation from a fresh
perspective catches much more.

~mck

[brettryan]

On 9 Jul 2015, at 01:24, mck [email protected] wrote:

On 8 July 2015 at 13:39, Brett Ryan [email protected] wrote:

It's cool, I'm happy to help where I'm able. If I can I really would like
to help with documentation of tiles. It could be me but sometimes I find it
a tiny bit sparse :)

Yeah that would be hugely appreciated. Often documentation from a fresh
perspective catches much more.

Not a problem, I'll post something on the dev list to talk about where I could best help. I can't say I can put in a huge amount of time, but I can at least contribute a few hours or so a week to support the project. It would also help me get a better understanding/appreciation. I somehow skipped tiles in the struts days.