Help using EditLink component

[Chris Mattmann]

Hi Guys,

How are ya? I have a question about the EditLink component. I am trying to
use it to edit an object of type gov.nasa.jpl.edrn.Participant. I have the
following simple code snippet in my Trails application's Home.page:

<p>
<a href="#" jwcid="@trails:EditLink"
 model="ognl:page.persistenceService.getInstance(gov.nasa.jpl.edrn.Participa
nt.class)" >Add a new Participant</a>
</p>

It's hard to find examples of how to use this EditLink component on the web.
I need it though because I don't want to use the ListAllLink component (that
trails uses by default), as I only want to shown certain objects (like the
gov.nasa.jpl.edrn.Participant one) and allow users to add/edit them. By
browsing around different examples, and the FishEye web repo, I thought
maybe the above snippet would work, but it gives me an error (partial stack
trace shown):

org.apache.tapestry.BindingException: Unable to parse OGNL expression
'model': model [classpath:/org/trails/component/EditLink.jwc, line 9, column
30]
        at
org.apache.tapestry.binding.ExpressionBinding.resolveExpression(ExpressionBi
nding.java:145)
        at
org.apache.tapestry.binding.ExpressionBinding.getObject(ExpressionBinding.ja
va:125)
        at
org.apache.tapestry.binding.AbstractBinding.getObject(AbstractBinding.java:8
4)
        at $ExternalLink_12.getParameters($ExternalLink_12.java)
        at
org.apache.tapestry.link.ExternalLink.getLink(ExternalLink.java:40)
        at
org.apache.tapestry.link.DefaultLinkRenderer.constructURL(DefaultLinkRendere
r.java:120)
        at
org.apache.tapestry.link.DefaultLinkRenderer.renderLink(DefaultLinkRenderer.
java:68)
        at
org.apache.tapestry.link.AbstractLinkComponent.renderComponent(AbstractLinkC
omponent.java:94)
        at
org.apache.tapestry.AbstractComponent.render(AbstractComponent.java:725)


[..snip..]

Caused by: org.apache.hivemind.ApplicationRuntimeException: Unable to parse
OGNL expression 'model': model
        at
org.apache.tapestry.services.impl.ExpressionCacheImpl.parse(ExpressionCacheI
mpl.java:156)
        at
org.apache.tapestry.services.impl.ExpressionCacheImpl.getCompiledExpression(
ExpressionCacheImpl.java:115)
        at
$ExpressionCache_1189177e273.getCompiledExpression($ExpressionCache_1189177e
273.java)
        at
org.apache.tapestry.binding.ExpressionBinding.resolveExpression(ExpressionBi
nding.java:134)
        ... 89 more
Caused by: ognl.OgnlException: model [org.apache.tapestry.BindingException:
Unable to parse OGNL expression
'page.persistenceService.getInstance(gov.nasa.jpl.edrn.Participant.class)':
$HomePage_0.gov [context:/WEB-INF/Home.html, line 7]]
        at ognl.OgnlRuntime.getMethodValue(OgnlRuntime.java:1215)
        at
ognl.ObjectPropertyAccessor.getPossibleProperty(ObjectPropertyAccessor.java:
60)
        at
ognl.ObjectPropertyAccessor.getProperty(ObjectPropertyAccessor.java:144)

[..snip..]

As far as I can tell the TrailsPage component that all pages inherit from
(I'm guessing the Home.page does too) provides the persistenceService, so I
should be able to access it from ognl:, and as far as I can tell as well,
the model="" parameter of the EditLink expects a java.lang.Object, which I'm
guessing is the object to bring up an edit page for. The weirdest thing is,
if I change my EditLink call above to:

<a href="#" jwcid="@trails:EditLink" model="ognl:new
gov.nasa.jpl.edrn.Participant()">Add a New Participant</a>

The link renders on my Home.page, but when I click it, I get a null pointer
exception message when it tries to take me to the EditPage. So I guess that
Hibernate probably sets up some magic in the Participant object returned
from persistenceService.getInstance that my regular old new Participant()
call didn't do. So, I thought that calling it would fix the problem but it
didn't. Can anyone help me?

Thanks!

Cheers,
 Chris



______________________________________________
Chris Mattmann, Ph.D.
Chris.Mattmann@...
Cognizant Development Engineer
Early Detection Research Network Project
_________________________________________________
Jet Propulsion Laboratory            Pasadena, CA
Office: 171-266B                     Mailstop:  171-246
_______________________________________________________

Disclaimer:  The opinions presented within are my own and do not reflect
those of either NASA, JPL, or the California Institute of Technology.



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[Alejandro Scandroli]

Hi Chris

The first error is due to the ognl expression This is how you
reference a class from ognl:
"ognl:@gov.nasa.jpl.edrn.Participant@class"
http://www.ognl.org/2.6.9/Documentation/html/LanguageGuide/staticMethods.html

You are right, the EditLink expects an hibernate entity so that code
won't work. You can try something like this

 <a href="#" jwcid="@trails:EditLink"
model="ognl:page.persistenceService.getInstance(@gov.nasa.jpl.edrn.Participant@class,
1)" >
Edit Participant Nº 1
</a>

That should work, but I have never tried it.

I think that the NewLink component is what you are looking for.
Try with this:

<a class="newlink" href="#" jwcid="@trails:NewLink"
type="ognl:@gov.nasa.jpl.edrn.Participant@class">Add a New
Participant</a>

I know Trails lacks good documentation :( ,and I'm responsible for
that, so this mailing list is the best way to get some help.


Hope this helps.
Let me know how it goes.
Saludos.
Alejandro.


--
Alejandro Scandroli - http://weblog.amneris.es/
Amneris: We build process-driven web applications.
http://www.amneris.es




On Sun, Mar 9, 2008 at 4:04 AM, Chris Mattmann
<chris.mattmann@...> wrote:

> Hi Guys,
>
>  How are ya? I have a question about the EditLink component. I am trying to
>  use it to edit an object of type gov.nasa.jpl.edrn.Participant. I have the
>  following simple code snippet in my Trails application's Home.page:
>
>  <p>
>  <a href="#" jwcid="@trails:EditLink"
>   model="ognl:page.persistenceService.getInstance(gov.nasa.jpl.edrn.Participa
>  nt.class)" >Add a new Participant</a>
>  </p>
>
>  It's hard to find examples of how to use this EditLink component on the web.
>  I need it though because I don't want to use the ListAllLink component (that
>  trails uses by default), as I only want to shown certain objects (like the
>  gov.nasa.jpl.edrn.Participant one) and allow users to add/edit them. By
>  browsing around different examples, and the FishEye web repo, I thought
>  maybe the above snippet would work, but it gives me an error (partial stack
>  trace shown):
>
>  org.apache.tapestry.BindingException: Unable to parse OGNL expression
>  'model': model [classpath:/org/trails/component/EditLink.jwc, line 9, column
>  30]
>         at
>  org.apache.tapestry.binding.ExpressionBinding.resolveExpression(ExpressionBi
>  nding.java:145)
>         at
>  org.apache.tapestry.binding.ExpressionBinding.getObject(ExpressionBinding.ja
>  va:125)
>         at
>  org.apache.tapestry.binding.AbstractBinding.getObject(AbstractBinding.java:8
>  4)
>         at $ExternalLink_12.getParameters($ExternalLink_12.java)
>         at
>  org.apache.tapestry.link.ExternalLink.getLink(ExternalLink.java:40)
>         at
>  org.apache.tapestry.link.DefaultLinkRenderer.constructURL(DefaultLinkRendere
>  r.java:120)
>         at
>  org.apache.tapestry.link.DefaultLinkRenderer.renderLink(DefaultLinkRenderer.
>  java:68)
>         at
>  org.apache.tapestry.link.AbstractLinkComponent.renderComponent(AbstractLinkC
>  omponent.java:94)
>         at
>  org.apache.tapestry.AbstractComponent.render(AbstractComponent.java:725)
>
>
>  [..snip..]
>
>  Caused by: org.apache.hivemind.ApplicationRuntimeException: Unable to parse
>  OGNL expression 'model': model
>         at
>  org.apache.tapestry.services.impl.ExpressionCacheImpl.parse(ExpressionCacheI
>  mpl.java:156)
>         at
>  org.apache.tapestry.services.impl.ExpressionCacheImpl.getCompiledExpression(
>  ExpressionCacheImpl.java:115)
>         at
>  $ExpressionCache_1189177e273.getCompiledExpression($ExpressionCache_1189177e
>  273.java)
>         at
>  org.apache.tapestry.binding.ExpressionBinding.resolveExpression(ExpressionBi
>  nding.java:134)
>         ... 89 more
>  Caused by: ognl.OgnlException: model [org.apache.tapestry.BindingException:
>  Unable to parse OGNL expression
>  'page.persistenceService.getInstance(gov.nasa.jpl.edrn.Participant.class)':
>  $HomePage_0.gov [context:/WEB-INF/Home.html, line 7]]
>         at ognl.OgnlRuntime.getMethodValue(OgnlRuntime.java:1215)
>         at
>  ognl.ObjectPropertyAccessor.getPossibleProperty(ObjectPropertyAccessor.java:
>  60)
>         at
>  ognl.ObjectPropertyAccessor.getProperty(ObjectPropertyAccessor.java:144)
>
>  [..snip..]
>
>  As far as I can tell the TrailsPage component that all pages inherit from
>  (I'm guessing the Home.page does too) provides the persistenceService, so I
>  should be able to access it from ognl:, and as far as I can tell as well,
>  the model="" parameter of the EditLink expects a java.lang.Object, which I'm
>  guessing is the object to bring up an edit page for. The weirdest thing is,
>  if I change my EditLink call above to:
>
>  <a href="#" jwcid="@trails:EditLink" model="ognl:new
>  gov.nasa.jpl.edrn.Participant()">Add a New Participant</a>
>
>  The link renders on my Home.page, but when I click it, I get a null pointer
>  exception message when it tries to take me to the EditPage. So I guess that
>  Hibernate probably sets up some magic in the Participant object returned
>  from persistenceService.getInstance that my regular old new Participant()
>  call didn't do. So, I thought that calling it would fix the problem but it
>  didn't. Can anyone help me?
>
>  Thanks!
>
>  Cheers,
>   Chris
>
>
>
>  ______________________________________________
>  Chris Mattmann, Ph.D.
>  Chris.Mattmann@...
>  Cognizant Development Engineer
>  Early Detection Research Network Project
>  _________________________________________________
>  Jet Propulsion Laboratory            Pasadena, CA
>  Office: 171-266B                     Mailstop:  171-246
>  _______________________________________________________
>
>  Disclaimer:  The opinions presented within are my own and do not reflect
>  those of either NASA, JPL, or the California Institute of Technology.
>
>
>
>  ---------------------------------------------------------------------
>  To unsubscribe from this list, please visit:
>
>     http://xircles.codehaus.org/manage_email
>
>
>

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[Chris Mattmann]

Hi Alejandro,

Thanks for your email!

This code:

> <a class="newlink" href="#" jwcid="@trails:NewLink"
> type="ognl:@gov.nasa.jpl.edrn.Participant@class">Add a New
> Participant</a>

Worked fine, and took me to the edit page, for a new entity, which is
exactly what I wanted to happen. Also, your code to edit a Participant makes
sense, and I will try it out.

I appreciate your help!

Cheers,
 Chris



On 3/9/08 8:07 AM, "Alejandro Scandroli" <alejandroscandroli@...>
wrote:

> Hi Chris
>
> The first error is due to the ognl expression This is how you
> reference a class from ognl:
> "ognl:@gov.nasa.jpl.edrn.Participant@class"
> http://www.ognl.org/2.6.9/Documentation/html/LanguageGuide/staticMethods.html
>
> You are right, the EditLink expects an hibernate entity so that code
> won't work. You can try something like this
>
>  <a href="#" jwcid="@trails:EditLink"
> model="ognl:page.persistenceService.getInstance(@gov.nasa.jpl.edrn.Participant
> @class,
> 1)" >
> Edit Participant Nº 1
> </a>
>
> That should work, but I have never tried it.
>
> I think that the NewLink component is what you are looking for.
> Try with this:
>
> <a class="newlink" href="#" jwcid="@trails:NewLink"
> type="ognl:@gov.nasa.jpl.edrn.Participant@class">Add a New
> Participant</a>
>
> I know Trails lacks good documentation :( ,and I'm responsible for
> that, so this mailing list is the best way to get some help.
>
>
> Hope this helps.
> Let me know how it goes.
> Saludos.
> Alejandro.
>
>
> --
> Alejandro Scandroli - http://weblog.amneris.es/
> Amneris: We build process-driven web applications.
> http://www.amneris.es
>
>
>
>
> On Sun, Mar 9, 2008 at 4:04 AM, Chris Mattmann
> <chris.mattmann@...> wrote:
>> Hi Guys,
>>
>>  How are ya? I have a question about the EditLink component. I am trying to
>>  use it to edit an object of type gov.nasa.jpl.edrn.Participant. I have the
>>  following simple code snippet in my Trails application's Home.page:
>>
>>  <p>
>>  <a href="#" jwcid="@trails:EditLink"
>>   model="ognl:page.persistenceService.getInstance(gov.nasa.jpl.edrn.Participa
>>  nt.class)" >Add a new Participant</a>
>>  </p>
>>
>>  It's hard to find examples of how to use this EditLink component on the web.
>>  I need it though because I don't want to use the ListAllLink component (that
>>  trails uses by default), as I only want to shown certain objects (like the
>>  gov.nasa.jpl.edrn.Participant one) and allow users to add/edit them. By
>>  browsing around different examples, and the FishEye web repo, I thought
>>  maybe the above snippet would work, but it gives me an error (partial stack
>>  trace shown):
>>
>>  org.apache.tapestry.BindingException: Unable to parse OGNL expression
>>  'model': model [classpath:/org/trails/component/EditLink.jwc, line 9, column
>>  30]
>>         at
>>  org.apache.tapestry.binding.ExpressionBinding.resolveExpression(ExpressionBi
>>  nding.java:145)
>>         at
>>  org.apache.tapestry.binding.ExpressionBinding.getObject(ExpressionBinding.ja
>>  va:125)
>>         at
>>  org.apache.tapestry.binding.AbstractBinding.getObject(AbstractBinding.java:8
>>  4)
>>         at $ExternalLink_12.getParameters($ExternalLink_12.java)
>>         at
>>  org.apache.tapestry.link.ExternalLink.getLink(ExternalLink.java:40)
>>         at
>>  org.apache.tapestry.link.DefaultLinkRenderer.constructURL(DefaultLinkRendere
>>  r.java:120)
>>         at
>>  org.apache.tapestry.link.DefaultLinkRenderer.renderLink(DefaultLinkRenderer.
>>  java:68)
>>         at
>>  org.apache.tapestry.link.AbstractLinkComponent.renderComponent(AbstractLinkC
>>  omponent.java:94)
>>         at
>>  org.apache.tapestry.AbstractComponent.render(AbstractComponent.java:725)
>>
>>
>>  [..snip..]
>>
>>  Caused by: org.apache.hivemind.ApplicationRuntimeException: Unable to parse
>>  OGNL expression 'model': model
>>         at
>>  org.apache.tapestry.services.impl.ExpressionCacheImpl.parse(ExpressionCacheI
>>  mpl.java:156)
>>         at
>>  org.apache.tapestry.services.impl.ExpressionCacheImpl.getCompiledExpression(
>>  ExpressionCacheImpl.java:115)
>>         at
>>  $ExpressionCache_1189177e273.getCompiledExpression($ExpressionCache_1189177e
>>  273.java)
>>         at
>>  org.apache.tapestry.binding.ExpressionBinding.resolveExpression(ExpressionBi
>>  nding.java:134)
>>         ... 89 more
>>  Caused by: ognl.OgnlException: model [org.apache.tapestry.BindingException:
>>  Unable to parse OGNL expression
>>  'page.persistenceService.getInstance(gov.nasa.jpl.edrn.Participant.class)':
>>  $HomePage_0.gov [context:/WEB-INF/Home.html, line 7]]
>>         at ognl.OgnlRuntime.getMethodValue(OgnlRuntime.java:1215)
>>         at
>>  ognl.ObjectPropertyAccessor.getPossibleProperty(ObjectPropertyAccessor.java:
>>  60)
>>         at
>>  ognl.ObjectPropertyAccessor.getProperty(ObjectPropertyAccessor.java:144)
>>
>>  [..snip..]
>>
>>  As far as I can tell the TrailsPage component that all pages inherit from
>>  (I'm guessing the Home.page does too) provides the persistenceService, so I
>>  should be able to access it from ognl:, and as far as I can tell as well,
>>  the model="" parameter of the EditLink expects a java.lang.Object, which I'm
>>  guessing is the object to bring up an edit page for. The weirdest thing is,
>>  if I change my EditLink call above to:
>>
>>  <a href="#" jwcid="@trails:EditLink" model="ognl:new
>>  gov.nasa.jpl.edrn.Participant()">Add a New Participant</a>
>>
>>  The link renders on my Home.page, but when I click it, I get a null pointer
>>  exception message when it tries to take me to the EditPage. So I guess that
>>  Hibernate probably sets up some magic in the Participant object returned
>>  from persistenceService.getInstance that my regular old new Participant()
>>  call didn't do. So, I thought that calling it would fix the problem but it
>>  didn't. Can anyone help me?
>>
>>  Thanks!
>>
>>  Cheers,
>>   Chris
>>
>>
>>
>>  ______________________________________________
>>  Chris Mattmann, Ph.D.
>>  Chris.Mattmann@...
>>  Cognizant Development Engineer
>>  Early Detection Research Network Project
>>  _________________________________________________
>>  Jet Propulsion Laboratory            Pasadena, CA
>>  Office: 171-266B                     Mailstop:  171-246
>>  _______________________________________________________
>>
>>  Disclaimer:  The opinions presented within are my own and do not reflect
>>  those of either NASA, JPL, or the California Institute of Technology.
>>
>>
>>
>>  ---------------------------------------------------------------------
>>  To unsubscribe from this list, please visit:
>>
>>     http://xircles.codehaus.org/manage_email
>>
>>
>>
>
> ---------------------------------------------------------------------
> To unsubscribe from this list, please visit:
>
>     http://xircles.codehaus.org/manage_email
>
>

______________________________________________
Chris Mattmann, Ph.D.
Chris.Mattmann@...
Cognizant Development Engineer
Early Detection Research Network Project
_________________________________________________
Jet Propulsion Laboratory            Pasadena, CA
Office: 171-266B                     Mailstop:  171-246
_______________________________________________________

Disclaimer:  The opinions presented within are my own and do not reflect
those of either NASA, JPL, or the California Institute of Technology.



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