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Posted to taglibs-user@tomcat.apache.org by Shelly Mujtaba <sh...@jgsullivan.com> on 2001/07/05 16:34:35 UTC
Most useful Tag library Poll
Hi,
I am preparing a presentation on Jakarta taglibs for my team. I wanted to
get some opinions from experts on this board.
Basically I am looking for a tag library which you find most useful in your
development work, a brief description of why?, would be useful also. I hope
to use this taglib for my presentation.
I understand that all of us work in vastly different domains, what useful
for me may not be for you. But I am hoping to find some commonality
eventually.
thanks a bunch.
shelly Mujtaba
-----Original Message-----
From: Kees Jongenburger [mailto:keesj@framfab.nl]
Sent: Wednesday, July 04, 2001 8:17 AM
To: taglibs-user@jakarta.apache.org
Subject: jsp:include in custom tags
Hi,
can please someone tell me how to dynamically
include file withing a custom tag.
none of the methods seam to work
<% String testpage = "test.jsp"; %> gives:
<jsp:include page="<%= testpage %>"/>
jsp:include needs to have "flush=true"
<% String testpage = "test.jsp"; %>
<jsp:include page="<%= testpage %>" flush="true"/>
Illegal to flush within a custom tag
any clues?
Re: xtag:context and xtag:variable
Posted by James Strachan <ja...@yahoo.co.uk>.
From: "William C. Robertson" <in...@bytetherapy.com>
> For xtags.variable, need I only specify: node="list" to load a
> Java.util.List class loaded with the results of a select?
Yes.
> Thank you for elucidating the use of the "distinct" operator in xpath, I
am
> now able to simplify my xml docs and speed up my code (the zvon tutorial
> doesn't cover that attribute).
The sort and distinct attributes are not part of XPath per se. The <xtags:*>
tags do not match exactly the XSLT tags so there are a few differences (such
as sort & distinct attributes on <xtags:forEach>)
James
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RE: xtag:context and xtag:variable
Posted by "William C. Robertson" <in...@bytetherapy.com>.
Thanks for your reply. I thought about the "superfluous" quality of context
and I can't come up with a case where forEach would not work equally well.
For xtags.variable, need I only specify: node="list" to load a
Java.util.List class loaded with the results of a select?
Thank you for elucidating the use of the "distinct" operator in xpath, I am
now able to simplify my xml docs and speed up my code (the zvon tutorial
doesn't cover that attribute).
Thanks again for your reply and thanks for all your work.
-Bill
-----Original Message-----
From: James Strachan [mailto:james_strachan@yahoo.co.uk]
Sent: Thursday, July 12, 2001 10:40 PM
To: taglibs-user@jakarta.apache.org
Subject: Re: xtag:context and xtag:variable
HI William
From: "William C. Robertson" <in...@bytetherapy.com>
>
> <xtag:context> does not seem to behave the same as it's cousin
> <xtag:forEach>. For the same path, forEach works but context doesn't. Is
> there something I'm missing?
<xtags:forEach> is meant to loop whereas <xtags:context> isn't but you're
right apart from that they should be similar.
Do you have an example of something that doesn't work?
<xtags:context> is more intended to help factorize the use of XPath.
e.g.
<xtags:valueOf select="/customers/customer[@id='123']/name">
<xtags:valueOf select="/customers/customer[@id='123']/address">
<xtags:valueOf select="/customers/customer[@id='123']/email">
Could be
<xtags:context select="/customers/customer[@id='123']">
<xtags:valueOf select="name">
<xtags:valueOf select="address">
<xtags:valueOf select="email">
</xtags:context>
Strictly speaking the above could be accomplished with <xtags:forEach>
instead, the <xtags:context> tag is kinda superfluous but some users liked
it as it explicitly will not loop.
> <xtag:variable> will return "an Object or List" if "node" is not
specified.
> Is the list a list in the sense of a "linkedList" or part of the io
package?
> Where can I find out about how to use it?
I'm in the middle of converting xtags over to the new build process and as a
result I've been doing much more documentation on the attributes used in the
tags, so hopefully in a few days time you'll have some much better
documentation.
Part of the problem is that an XPath expression could result in a String,
Number, Boolean, List or Node. So there is a type attribute to indicate what
type of variable you want. I've found most of the time people want Strings
so I've made string the default. Also it can get a bit ugly using the real
Java class names in JSP so I added some simple aliases as an option as well.
The alias names are:
string
number
list
object
node
The real class names are
java.lang.String
java.lang.Number
java.util.List
java.lang.Object
org.dom4j.Node
One of the main reasons for the <xtags:variable> tag is so that an XPath
expression can be evaluated and the resulting object can be reused several
times by passing it in as the context into other tags like <xtags:forEach>
or <xtags:valueOf>.
> I am currently loading a string array to step through because I haven't
> found an XPath alternative to SQL's "DISTINCT" operator. Does anyone have
a
> more elegant solution?
The <xtags:forEach> tag has sorting and removing distincts built in. So if
you want to iterate through your customers, in name order removing
duplicates the following should work...
XML...
<customers>
<customer>
<name>william</name>
<location>?</location>
</customer>
<customer>
<name>james</name>
<location>London</location>
</customer>
</customer>
<xtags:forEach select="/customers/customer" sort="name" distinct="true">
Name: <xtags:valueOf select="name"/>
Location: <xtags:valueOf select="location"/>
</xtags:forEach>
Where the sort attribute is another XPath expression, evaluated on each
resulting node and is used for the comparison.
Does that help at all?
James
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Re: xtag:context and xtag:variable
Posted by James Strachan <ja...@yahoo.co.uk>.
HI William
From: "William C. Robertson" <in...@bytetherapy.com>
>
> <xtag:context> does not seem to behave the same as it's cousin
> <xtag:forEach>. For the same path, forEach works but context doesn't. Is
> there something I'm missing?
<xtags:forEach> is meant to loop whereas <xtags:context> isn't but you're
right apart from that they should be similar.
Do you have an example of something that doesn't work?
<xtags:context> is more intended to help factorize the use of XPath.
e.g.
<xtags:valueOf select="/customers/customer[@id='123']/name">
<xtags:valueOf select="/customers/customer[@id='123']/address">
<xtags:valueOf select="/customers/customer[@id='123']/email">
Could be
<xtags:context select="/customers/customer[@id='123']">
<xtags:valueOf select="name">
<xtags:valueOf select="address">
<xtags:valueOf select="email">
</xtags:context>
Strictly speaking the above could be accomplished with <xtags:forEach>
instead, the <xtags:context> tag is kinda superfluous but some users liked
it as it explicitly will not loop.
> <xtag:variable> will return "an Object or List" if "node" is not
specified.
> Is the list a list in the sense of a "linkedList" or part of the io
package?
> Where can I find out about how to use it?
I'm in the middle of converting xtags over to the new build process and as a
result I've been doing much more documentation on the attributes used in the
tags, so hopefully in a few days time you'll have some much better
documentation.
Part of the problem is that an XPath expression could result in a String,
Number, Boolean, List or Node. So there is a type attribute to indicate what
type of variable you want. I've found most of the time people want Strings
so I've made string the default. Also it can get a bit ugly using the real
Java class names in JSP so I added some simple aliases as an option as well.
The alias names are:
string
number
list
object
node
The real class names are
java.lang.String
java.lang.Number
java.util.List
java.lang.Object
org.dom4j.Node
One of the main reasons for the <xtags:variable> tag is so that an XPath
expression can be evaluated and the resulting object can be reused several
times by passing it in as the context into other tags like <xtags:forEach>
or <xtags:valueOf>.
> I am currently loading a string array to step through because I haven't
> found an XPath alternative to SQL's "DISTINCT" operator. Does anyone have
a
> more elegant solution?
The <xtags:forEach> tag has sorting and removing distincts built in. So if
you want to iterate through your customers, in name order removing
duplicates the following should work...
XML...
<customers>
<customer>
<name>william</name>
<location>?</location>
</customer>
<customer>
<name>james</name>
<location>London</location>
</customer>
</customer>
<xtags:forEach select="/customers/customer" sort="name" distinct="true">
Name: <xtags:valueOf select="name"/>
Location: <xtags:valueOf select="location"/>
</xtags:forEach>
Where the sort attribute is another XPath expression, evaluated on each
resulting node and is used for the comparison.
Does that help at all?
James
_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com
Re: xtag:context and xtag:variable
Posted by James Strachan <ja...@yahoo.co.uk>.
Hi William
(I'm reposting this as my previous post seemed to vanish)
From: "William C. Robertson" <in...@bytetherapy.com>
>
> <xtag:context> does not seem to behave the same as it's cousin
> <xtag:forEach>. For the same path, forEach works but context doesn't. Is
> there something I'm missing?
<xtags:forEach> is meant to loop whereas <xtags:context> isn't but you're
right apart from that they should be similar.
Do you have an example of something that doesn't work?
<xtags:context> is more intended to help factorize the use of XPath.
e.g.
<xtags:valueOf select="/customers/customer[@id='123']/name">
<xtags:valueOf select="/customers/customer[@id='123']/address">
<xtags:valueOf select="/customers/customer[@id='123']/email">
Could be
<xtags:context select="/customers/customer[@id='123']">
<xtags:valueOf select="name">
<xtags:valueOf select="address">
<xtags:valueOf select="email">
</xtags:context>
Strictly speaking the above could be accomplished with <xtags:forEach>
instead, the <xtags:context> tag is kinda superfluous but some users liked
it as it explicitly will not loop.
> <xtag:variable> will return "an Object or List" if "node" is not
specified.
> Is the list a list in the sense of a "linkedList" or part of the io
package?
> Where can I find out about how to use it?
I'm in the middle of converting xtags over to the new build process and as a
result I've been doing much more documentation on the attributes used in the
tags, so hopefully in a few days time you'll have some much better
documentation.
Part of the problem is that an XPath expression could result in a String,
Number, Boolean, List or Node. So there is a type attribute to indicate what
type of variable you want. I've found most of the time people want Strings
so I've made string the default. Also it can get a bit ugly using the real
Java class names in JSP so I added some simple aliases as an option as well.
The alias names are:
string
number
list
object
node
The real class names are
java.lang.String
java.lang.Number
java.util.List
java.lang.Object
org.dom4j.Node
One of the main reasons for the <xtags:variable> tag is so that an XPath
expression can be evaluated and the resulting object can be reused several
times by passing it in as the context into other tags like <xtags:forEach>
or <xtags:valueOf>.
> I am currently loading a string array to step through because I haven't
> found an XPath alternative to SQL's "DISTINCT" operator. Does anyone have
a
> more elegant solution?
The <xtags:forEach> tag has sorting and removing distincts built in. So if
you want to iterate through your customers, in name order removing
duplicates the following should work...
XML...
<customers>
<customer>
<name>william</name>
<location>?</location>
</customer>
<customer>
<name>james</name>
<location>London</location>
</customer>
</customer>
<xtags:forEach select="/customers/customer" sort="name" distinct="true">
Name: <xtags:valueOf select="name"/>
Location: <xtags:valueOf select="location"/>
</xtags:forEach>
Where the sort attribute is another XPath expression, evaluated on each
resulting node and is used for the comparison.
Does that help at all?
James
_________________________________________________________
Do You Yahoo!?
Get your free @yahoo.com address at http://mail.yahoo.com
xtag:context and xtag:variable
Posted by "William C. Robertson" <in...@bytetherapy.com>.
Hello all,
<xtag:context> does not seem to behave the same as it's cousin
<xtag:forEach>. For the same path, forEach works but context doesn't. Is
there something I'm missing?
<xtag:variable> will return "an Object or List" if "node" is not specified.
Is the list a list in the sense of a "linkedList" or part of the io package?
Where can I find out about how to use it?
I am currently loading a string array to step through because I haven't
found an XPath alternative to SQL's "DISTINCT" operator. Does anyone have a
more elegant solution?
Any help would be greatly appreciated.....
Re: Re[2]: Most useful Tag library Poll
Posted by James Strachan <ja...@yahoo.co.uk>.
From: "daljeetsingh" <da...@softhome.net>
> > Maybe the DBtaglib is the most used library. I mean... I cannot think of
a
> > Web application without DB access.
>
> The DBtaglib approach throws the MVC right out of the window. Is it
> really the way to go?
Right tool for the right job. There is no correct answer or single design
pattern that should be followed religously for all cases. It depends on
complexity.
a) Sometimes doing a full model 1, 2, or pull based MVC architecture
together with EJBs, session beans, entity beans, data access objects and so
forth is useful and necessary. Sometimes its using a sledgehammer to crack a
nut.
b) Sometimes a simple MVC model where model JSP pages do SQL or use beans to
output XML which then gets styled by view JSPs with XSLT is a nice simple
seperation of model from view with custom Java actions (beans and/or
servlets) for the controllers.
c) Sometimes getting a web site up and working fast is more important so
doing a few simple JSP pages with embedded SQL is fine.
Generally though some kind of MVC architecture is recommended for modestly
complex systems. I tend to favour option b) to start with then refactor to
more complex EJB style implementations a) if and when necessary.
James
_________________________________________________________
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Re[2]: Most useful Tag library Poll
Posted by daljeetsingh <da...@softhome.net>.
> Maybe the DBtaglib is the most used library. I mean... I cannot think of a
> Web application without DB access.
The DBtaglib approach throws the MVC right out of the window. Is it
really the way to go?
Bye
Daljeet Singh
ecExperts India
Ph:- (O) +91-11-4670906
(R) +91-11-7125680
ICQ:- 75129600
Yahoo:- daljeetsinghmaken
Re: Most useful Tag library Poll
Posted by Sam Newman <sa...@stamplets.com>.
Personally, the tags I use the most are the request and session tags,
however the ones which do the most amount of work for me are probably the
input tags - those used for form validation/pre-filling.
sam
----- Original Message -----
From: "Howie" <ca...@TooDarkPark.org>
To: <ta...@jakarta.apache.org>
Cc: <ca...@TooDarkPark.org>
Sent: Thursday, July 05, 2001 8:39 PM
Subject: RE: Most useful Tag library Poll
> On Thu, 5 Jul 2001, mihai manuta wrote:
>
> > Maybe the DBtaglib is the most used library. I mean... I cannot think of
a
> > Web application without DB access.
>
> just because a web app talks to a DB doesnt necessarily mean it has to use
> DBTags :)
>
> none of the applications ive seen ( or helped out on ) have used DBTags..
> instead, other Factory classes fetch instances of objects, then provide
> those to the JSP/servlet.
>
> ---
> Howie <ca...@toodarkpark.org> URL: http://www.toodarkpark.org
> "This sort of thing has cropped up before and has always been
> due to human error." -- HAL
>
RE: Most useful Tag library Poll
Posted by Howie <ca...@TooDarkPark.org>.
On Thu, 5 Jul 2001, mihai manuta wrote:
> Maybe the DBtaglib is the most used library. I mean... I cannot think of a
> Web application without DB access.
just because a web app talks to a DB doesnt necessarily mean it has to use
DBTags :)
none of the applications ive seen ( or helped out on ) have used DBTags..
instead, other Factory classes fetch instances of objects, then provide
those to the JSP/servlet.
---
Howie <ca...@toodarkpark.org> URL: http://www.toodarkpark.org
"This sort of thing has cropped up before and has always been
due to human error." -- HAL
RE: Most useful Tag library Poll
Posted by mihai manuta <m....@mrted.com>.
Maybe the DBtaglib is the most used library. I mean... I cannot think of a
Web application without DB access.
Sincerely,
Mihai Manuta
m.manuta@mrted.com
tel: +336.73.56.57.92