Hi Mike,
Sorry I don't have better documentation... and I'm slow to respond right
now b/c my computer feezes up whenever I start the app server
(investigating right now) -- this makes it hard for me to give you
tested information. :(
See comments inline.
Mike Wright wrote:
> Hi Ken,
>
> Still no conditional "joy."
>
>
> If I copy, verbatim, the if example you sent to Anissa, I get a
> trace-back. If I change the <if> to <!if> I get:
Yes, it should be <!if [condition]>[some components...]</if>.
> This is the EE versionThis is the PE version.
Something doesn't seem right if you're seeing both... I wish I could
test to see (I will when my server is back up).
> Now, I didn't set any version attribute (and how exactly should I)?
setAttribute() handler. Or you can put a value in the request scope in
some other way (i.e. via java add a request attribute -- see
javax.faces.context.ExternalContext; or via a managed bean defined in
the faces-config.xml file).
> But, shouldn't the opposite of true be false?
Yes.
> Are the <!if> elements allowed to appear anywhere?
Anywhere a component is allowed.
> If there are restrictions on where they appear, what are those
> restrictions?
See above... + some components don't allow some child-components. This
may further restrict where they are used. This is standard JSF stuff.
In general I believe it is bad practice to design a component that can
only accept certain types of child components... IMO, it would be a bug
for components where this is the case (Breadcrumbs is one such component).
> If there are restrictions on which variables and expressions they can
> evaluate, what are they?
You should be able to use any ${} or #{} expression in conjunction w/
boolean literals (true/false) + the operators I mentioned.
> There's an awful lot of implied context here that isn't documented
> in these e-mails. I looked at PermissionChecker.java, but I'm not
> finding it helpful in setting up a working conditional example. Is
> there a unit test for the PermissionChecker that shows valid and
> invalid syntax?
There is a main() in this class which provides some testing. However,
this is only the boolean evaluation component of an <!if>, not an
end-to-end test case. There is no end-to-end test case yet.
> How do I set the $attribute("version") on the including page so that
> the <!if> on the included page can check it?
See answer above.
> How do I use the sessionScope variables instead?
$session{sessionKey} or #{sessionKey} or #{sessionScope.sessionKey}
> Can you send me a .jsf file that demonstrates the use of <!if>
> using a sessionScope string comparison?
Yes, I will send you a confirmed runnable example as soon as I am back
up and running.
> I prefer a runnable example to any e-mail or document, as there are
> too many typos or omissions to make the non-running examples
> reliable. This is especially important for a technology that has no
> books or white papers available, nor any online examples that one
> could google, nor much online discussion that one could google, nor
> any quantity of users whose blogs one could google. We really need
> comprehensive runnable examples (and I would argue we also need
> detailed runnable testcases).
I agree... volunteers? ;)
> BTW, I've spent several hours on this today. I imagine that
> external users attempting to understand jsftemplating are giving up
> with much less of a time investment.
Yes.
Ken
> Regards,
> Mike
> ---
>
> Ken Paulsen wrote:
>
>>
>> Hi Mike,
>>
>> The attached message was recently sent out re: <if>. Try: <!if true>
>> and <!if false>. You can also use the following operators:
>>
>> = // String comarison (actually uses "left.matches(right)"
>> so regexp may work)
>> | // Logical OR
>> & // Logical AND
>> ! // NOT
>> < // Less Than
>> > // Greater than
>> & // Modulus
>>
>> And of course, you can use ()'s to override the order of operations.
>>
>> See PermissionChecker.java for more info...
>>
>> Ken
>>
>> Mike Wright wrote:
>>
>>> Hi Ken,
>>>
>>> I'm having trouble with <!if>, are there any examples or tests
>>> that demonstrate how to use it?
>>>
>>>
>>> Whne I tried this:
>>>
>>>> "<br />(before)
>>>> <!if $boolean{true} >
>>>> "<br />true!
>>>> </!if>
>>>> <!if $boolean{false} >
>>>> "<br />false ?
>>>> </!if>
>>>> <!if $boolean{true} != $boolean{false} >
>>>> "<br />true does not equal false
>>>> </!if>
>>>> <!if $boolean{true} == $boolean{false} >
>>>> "<br />true equals false?!
>>>> </!if>
>>>> "<br />(afer)
>>>>
>>>
>>> I get this:
>>>
>>>> (before)
>>>> true!
>>>> true does not equal false
>>>> true equals false?!
>>>> (after)
>>>
>>>
>>> So why does the false expression evaluate to true?
>>>
>>>
>>> Also, if I try this:
>>>
>>>> <!if #{sessionScope["hasMetadataComponentTypeBreadcrumb"]} >
>>>> "<br />conditional breadcrumb link rendered=true
>>>> </!if>
>>>
>>>
>>> I get a traceback, about an element not being closed. If I try
>>> adding quotes, I get an expression that always evaluates to true.
>>>
>>>
>>> I've tried various other things, none of which have allowed me to
>>> conditionally wrap a set of elements. I grep'ed the admin-gui code
>>> and couldn't find any examples of using <!if>.
>>>
>>>
>>> Can you give concrete examples of how I can check a session variable
>>> for a true or false value in <!if>?
>>>
>>>
>>> In the meantime, I will use the two panelGroups with rendered
>>> attribute (complimentary) boolean expressions.
>>>
>>> Regards,
>>> Mike
>>> ---
>>>
>>>
>>>
>>> Ken Paulsen wrote:
>>>
>>>>
>>>> Hi Mike,
>>>>
>>>> For conditionally rendering components you can do anything you can
>>>> w/ vanilla JSF (i.e. rendered="false"... although you may need to
>>>> do $boolean{false} to properly convert it).
>>>>
>>>> You can also use the <if> component to use a boolean expression to
>>>> determine if its children should be rendered. However, if poorly
>>>> written components do not render all their children, or expect only
>>>> children of a particular type... they may not properly work with
>>>> the <if> component. (BTW, the if can be used as a regular
>>>> component or via special syntax: <!if [boolean expression]>
>>>> [conditionally rendered children] </if>).
>>>>
>>>> Looking at the Breadcrumbs source code (the source I have is old...
>>>> so perhaps its been fixed), it appears that:
>>>>
>>>> 1) They only allow Hyperlink components (bad)
>>>>
>>>> 2) They do not respect "rendered=false" components (bad)
>>>>
>>>> The code iterates over all children, casts each one unnecessarily
>>>> to a Hyperlink (it does use the "text" property, but could just as
>>>> easily use the "real" "value" property and do so via the attribute
>>>> map). It then unconditionally renders each one (which may be
>>>> hidden, so it won't show up) and immediately places the separator
>>>> (also unconditionally).
>>>>
>>>> So what you are attempting to do will not work because of the way
>>>> the component was written. You should file a bug against the
>>>> component and hope that it has already been fixed or that it will
>>>> soon.
>>>>
>>>> Good luck!
>>>>
>>>> Ken
>>>>
>>>> Mike Wright wrote:
>>>>
>>>>> I'm trying to get the displayed breadcrumbs to accurately show the
>>>>> path I followed to get to a (shared) page, but in order to support
>>>>> the maximum number of links in the breadcrumbs, I see a problem
>>>>> when the path requires fewer links. e.g.
>>>>>
>>>>> > good: Application Server > Integration Applications > JBI
>>>>> Components > Libraries > placeholder SL > jbi.xml
>>>>> > bad: Application Server > Integration Applications > JBI
>>>>> Deployments > > placeholder SA > jbi.xml
>>>>> > s/b: Application Server > Integration Applications > JBI
>>>>> Deployments > placeholder SA > jbi.xml
>>>>>
>>>>> I include a .jsf page from four other .jsf pages, with breadcrumbs
>>>>> in the included file. The "including" .jsf files set the
>>>>> text/link values for the variable breadcrumbs. I've tried also
>>>>> setting a boolean in the "including" .jsf files to use with a
>>>>> rendered attribute on the not-always-needed breadcrumb hyperlink
>>>>> and I've tried setting the text/link values to empty string when
>>>>> they are not needed, but I end up with an extra ">" separator.
>>>>> (I've tried various things for the argument of the rendered
>>>>> attribute; it appears that these don't evaluate to false?)
>>>>>
>>>>> What's the recommended jsftemplating "best practice" for
>>>>> expressing a variable number of conditionally rendered subelements?
>>>>>
>>>>> Is there a documented expression language that I can use and any
>>>>> example?
>>>>>
>>>>> Regards,
>>>>> Mike
>>>>
>>>>
>>
>> ------------------------------------------------------------------------
>>
>> Subject:
>> JSFTemplating: Re: How to use 'if'
>> From:
>> Ken Paulsen <Ken.Paulsen_at_Sun.COM>
>> Date:
>> Mon, 04 Sep 2006 15:14:04 -0700
>> To:
>> Anissa Lam <Anissa.Lam_at_Sun.COM>
>>
>> To:
>> Anissa Lam <Anissa.Lam_at_Sun.COM>
>> CC:
>> dev_at_jsftemplating.dev.java.net
>>
>>
>>
>> Hi Anissa,
>>
>> I may support this the way you listed below, however, the support
>> doesn't exist right now. (FYI, the basic support for this in
>> handlers is there as handlers can be hierarchical and conditionally
>> execute "child" handlers... but the syntax is not robust enough to
>> create this use case.)
>>
>> There is "if" support a the "(Layout)Component" level, however. This
>> allows you to make conditional areas of a page. Something like:
>>
>> <if $attribute{"version"}=EE>
>> "This is the EE Version
>> </if>
>> <if !($attribute{"version"}=EE)>
>> "This is the PE Version
>> </if>
>>
>> I'd like to expand this to support "else" and to expand this to
>> handlers... please file an enhancement request on issue tracker if
>> you can. In the mean time, I hope the above syntax will support what
>> you need.
>>
>> Thanks!
>>
>> Ken
>>
>> Anissa Lam wrote:
>>
>>> Hi Ken,
>>>
>>> I want to know if 'if' is supported in jsftemplating. If so, can
>>> you show us the syntax on how to use it ?
>>>
>>> Specificially, i am looking for something like this:
>>>
>>> <event>
>>> <! beforeEncode
>>> *if ( $attribute{"version"} == "EE") *{
>>> println(value="this is EE version");
>>> } ???? Can i use else here ?
>>> *if ($attribute{"version"} != "EE") *{
>>> println(value=" This is NOT EE version");
>>> }
>>> />
>>> </event>
>>>
>>> thanks
>>> Anissa
>>>