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Posted to user@struts.apache.org by Christopher Schultz <ch...@christopherschultz.net> on 2015/10/03 17:50:31 UTC
Accessing action properties from JSPs
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All,
Is this the latest wisdom for accessing action properties from JSPs
using EL?
https://struts.apache.org/docs/access-to-valuestack-from-jsps.html
So if my action has a "public String getItems)" method, I'd like to do
something as close as possible to this:
<c:forEach var="item" items="$action.items">
</c:forEach>
It looks like I can do this very quickly:
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<%@ taglib prefix="s" uri="/struts-tags" %>
<s:set var="action" value="items" />
<c:forEach var="item" value="${items}">
...
</c:forEach>
Is there something I can do to bind "action" to the actual action
instance?
Or I can use the Struts 2 "iterate" tag:
<%@ taglib prefix="s" uri="/struts-tags" %>
<s:iterator var="item" value="items">
</s:iterator>
I realize that this is a simple example, but is there a recommended
technique, here? EL gives me the ability to do things like print
values with somewhat less code: "${fn:escapeXml(foo)}" versus
<s:property escapeHtml="true" value="foo" />
In general, EL seems to be more universally understood, while the s2
tags are a bit more specialized.
Any suggestions are appreciated.
(After writing all of the above and experimenting, I've found that I
can reference ${items} in my JSP without doing anything with the
Struts2 tags: no <s:set> required. How is that working? Does S2 export
all my beans from the action (and other places?) to the request
attributes?).
Thanks,
- -chris
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RE: Accessing action properties from JSPs
Posted by Martin Gainty <mg...@hotmail.com>.
> To: user@struts.apache.org
> From: chris@christopherschultz.net
> Subject: Accessing action properties from JSPs
> Date: Sat, 3 Oct 2015 11:50:31 -0400
>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
>
> All,
>
> Is this the latest wisdom for accessing action properties from JSPs
> using EL?
>
> https://struts.apache.org/docs/access-to-valuestack-from-jsps.html
>
> So if my action has a "public String getItems)" method, I'd like to do
> something as close as possible to this:
>
> <c:forEach var="item" items="$action.items">
> </c:forEach>
>
> It looks like I can do this very quickly:
>
> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
> <%@ taglib prefix="s" uri="/struts-tags" %>
> <s:set var="action" value="items" />
> <c:forEach var="item" value="${items}">
> ...
> </c:forEach>
>
> Is there something I can do to bind "action" to the actual action
> instance?
MG>the <result...>jsp</result> is 'bound' inside struts-config.xml to parent <action tag
https://struts.apache.org/docs/action-configuration.html
MG>if on the other hand you want to use a different method to execute then you can use DMI
https://cwiki.apache.org/confluence/display/WW/Action+Configuration#ActionConfiguration-DynamicMethodInvocation
>
> Or I can use the Struts 2 "iterate" tag:
>
> <%@ taglib prefix="s" uri="/struts-tags" %>
> <s:iterator var="item" value="items">
> </s:iterator>
>
> I realize that this is a simple example, but is there a recommended
> technique, here? EL gives me the ability to do things like print
> values with somewhat less code: "${fn:escapeXml(foo)}" versus
> <s:property escapeHtml="true" value="foo" />
>
> In general, EL seems to be more universally understood, while the s2
> tags are a bit more specialized.
MG>s2 tag resolution provides access to struts value stack via OGNL expression(s)
>
> Any suggestions are appreciated.
>
> (After writing all of the above and experimenting, I've found that I
> can reference ${items} in my JSP without doing anything with the
> Struts2 tags: no <s:set> required. How is that working?
MG>in that case struts resolves this as a property placed on ValueStack
https://struts.apache.org/docs/tag-syntax.html
Does S2 export
> all my beans from the action (and other places?) to the request
> attributes?).
MG>if specified by scope attrib e.g. <s:set ...scope="request"/>
https://struts.apache.org/docs/set.html
>
> Thanks,
> - -chris
MG>does that answer your understanding of struts-tags?
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Re: Accessing action properties from JSPs
Posted by Christopher Schultz <ch...@christopherschultz.net>.
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Lukasz,
On 10/4/15 3:49 AM, Lukasz Lenart wrote:
> 2015-10-03 17:50 GMT+02:00 Christopher Schultz
> <ch...@christopherschultz.net>:
>> Is this the latest wisdom for accessing action properties from
>> JSPs using EL?
>>
>> https://struts.apache.org/docs/access-to-valuestack-from-jsps.html
>>
>>
>>
So if my action has a "public String getItems)" method, I'd like to do
>> something as close as possible to this:
>>
>> <c:forEach var="item" items="$action.items"> </c:forEach>
>>
>> It looks like I can do this very quickly:
>>
>> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
>> <%@ taglib prefix="s" uri="/struts-tags" %> <s:set var="action"
>> value="items" /> <c:forEach var="item" value="${items}"> ...
>> </c:forEach>
>>
>> Is there something I can do to bind "action" to the actual
>> action instance?
>>
>> Or I can use the Struts 2 "iterate" tag:
>>
>> <%@ taglib prefix="s" uri="/struts-tags" %> <s:iterator
>> var="item" value="items"> </s:iterator>
>>
>> I realize that this is a simple example, but is there a
>> recommended technique, here? EL gives me the ability to do things
>> like print values with somewhat less code: "${fn:escapeXml(foo)}"
>> versus <s:property escapeHtml="true" value="foo" />
>>
>> In general, EL seems to be more universally understood, while the
>> s2 tags are a bit more specialized.
>>
>> Any suggestions are appreciated.
>
> JSTL/EL are supported out-of-the-box
>
> https://struts.apache.org/docs/can-we-use-jstl-with-the-framework.html
>
>
>> (After writing all of the above and experimenting, I've found
>> that I can reference ${items} in my JSP without doing anything
>> with the Struts2 tags: no <s:set> required. How is that working?
>> Does S2 export all my beans from the action (and other places?)
>> to the request attributes?).
>
> The magic happens in StrutsRequestWrapper (Struts wraps each
> request with dedicated class). The wrapper first tries to fetch the
> attribute from the original request, if not found, it will use
> ValueStack to find the value.
>
> https://github.com/apache/struts/blob/master/core/src/main/java/org/ap
ache/struts2/dispatcher/StrutsRequestWrapper.java#L72-L104
Thanks
>
for the explanation. I'm very happy that this works... the
reference I provided at the top of my post suggests that working with
non-Struts2-provided tags could be difficult, but it hasn't been
difficult at all.
Thanks,
- -chris
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Re: Accessing action properties from JSPs
Posted by Lukasz Lenart <lu...@apache.org>.
2015-10-03 17:50 GMT+02:00 Christopher Schultz <ch...@christopherschultz.net>:
> Is this the latest wisdom for accessing action properties from JSPs
> using EL?
>
> https://struts.apache.org/docs/access-to-valuestack-from-jsps.html
>
> So if my action has a "public String getItems)" method, I'd like to do
> something as close as possible to this:
>
> <c:forEach var="item" items="$action.items">
> </c:forEach>
>
> It looks like I can do this very quickly:
>
> <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
> <%@ taglib prefix="s" uri="/struts-tags" %>
> <s:set var="action" value="items" />
> <c:forEach var="item" value="${items}">
> ...
> </c:forEach>
>
> Is there something I can do to bind "action" to the actual action
> instance?
>
> Or I can use the Struts 2 "iterate" tag:
>
> <%@ taglib prefix="s" uri="/struts-tags" %>
> <s:iterator var="item" value="items">
> </s:iterator>
>
> I realize that this is a simple example, but is there a recommended
> technique, here? EL gives me the ability to do things like print
> values with somewhat less code: "${fn:escapeXml(foo)}" versus
> <s:property escapeHtml="true" value="foo" />
>
> In general, EL seems to be more universally understood, while the s2
> tags are a bit more specialized.
>
> Any suggestions are appreciated.
JSTL/EL are supported out-of-the-box
https://struts.apache.org/docs/can-we-use-jstl-with-the-framework.html
> (After writing all of the above and experimenting, I've found that I
> can reference ${items} in my JSP without doing anything with the
> Struts2 tags: no <s:set> required. How is that working? Does S2 export
> all my beans from the action (and other places?) to the request
> attributes?).
The magic happens in StrutsRequestWrapper (Struts wraps each request
with dedicated class). The wrapper first tries to fetch the attribute
from the original request, if not found, it will use ValueStack to
find the value.
https://github.com/apache/struts/blob/master/core/src/main/java/org/apache/struts2/dispatcher/StrutsRequestWrapper.java#L72-L104
Regards
--
Łukasz
+ 48 606 323 122 http://www.lenart.org.pl/
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