What annotations are on the brand field of your Main class? Something has
changes that field to be read-only, which is usually a sign that a value was
injected.
On 5/4/07, Joel Wiegman <[EMAIL PROTECTED]> wrote:
Still getting unintuitive errors... I've added the ValueEncoder and now
when I submit the form I get the following stack trace (and yes the
"Main" component has a setBrand(Brand) method, which from the root cause
exception seems to be the cause of the problem?):
[ERROR] RequestExceptionHandler Processing of request failed with
uncaught exception:
org.apache.tapestry.ioc.internal.util.TapestryException: Failure writing
parameter value of component com.foo.pages.Main:brand: Field
com.foo.pages.Main.brand is read-only. [at context:WEB-INF/Main.html,
line 89, column 278]
java.lang.RuntimeException:
org.apache.tapestry.ioc.internal.util.TapestryException: Failure writing
parameter value of component com.foo.
pages.Main:brand: Field com.foo.pages.Main.brand is read-only. [at
context:WEB-INF/Main.html, line 89, column 278]
at
org.apache.tapestry.corelib.components.Form.onAction(Form.java:356)
at
org.apache.tapestry.corelib.components.Form.handleComponentEvent(Form.ja
va)
at
org.apache.tapestry.internal.structure.ComponentPageElementImpl.handleEv
ent(ComponentPageElementImpl.java:903)
at
org.apache.tapestry.internal.structure.ComponentPageElementImpl.triggerE
vent(ComponentPageElementImpl.java:1002)
at
org.apache.tapestry.internal.services.ActionLinkHandlerImpl.handle(Actio
nLinkHandlerImpl.java:100)
at
org.apache.tapestry.internal.services.ActionLinkHandlerImpl.handle(Actio
nLinkHandlerImpl.java:53)
at
$ActionLinkHandler_11258c2d07d.handle($ActionLinkHandler_11258c2d07d.jav
a)
at
org.apache.tapestry.internal.services.ComponentActionDispatcher.dispatch
(ComponentActionDispatcher.java:115)
... 40 more
Caused by: org.apache.tapestry.ioc.internal.util.TapestryException:
Failure writing parameter value of component com.foo.pages.Main:brand:
Field com.foo.pages.Main.brand is read-only. [at
context:WEB-INF/Main.html, line 89, column 278]
at
org.apache.tapestry.internal.structure.InternalComponentResourcesImpl.wr
iteParameter(InternalComponentResourcesImpl.java:223)
at
org.apache.tapestry.corelib.components.Select._$update_parameter_value_0
(Select.java)
at
org.apache.tapestry.corelib.components.Select.processSubmission(Select.j
ava:238)
at
org.apache.tapestry.corelib.base.AbstractField.processSubmission(Abstrac
tField.java:210)
at
org.apache.tapestry.corelib.base.AbstractField.access$100(AbstractField.
java:47)
at
org.apache.tapestry.corelib.base.AbstractField$ProcessSubmissionAction.e
xecute(AbstractField.java:116)
at
org.apache.tapestry.corelib.base.AbstractField$ProcessSubmissionAction.e
xecute(AbstractField.java:110)
at
org.apache.tapestry.corelib.components.Form.onAction(Form.java:347)
... 40 more
Caused by: org.apache.tapestry.ioc.internal.util.TapestryException:
Field com.foo.pages.Main.brand is read-only. [at context:WEB-INF/Main.
html, line 89, column 278]
at
org.apache.tapestry.internal.bindings.PropBinding.set(PropBinding.java:7
1)
at
org.apache.tapestry.internal.structure.InternalComponentResourcesImpl.wr
iteParameter(InternalComponentResourcesImpl.java:219)
... 47 more
Caused by: java.lang.RuntimeException: Field com.foo.pages.Main.brand is
read-only.
at com.foo.pages.Main._$write_brand(Main.java)
at com.foo.pages.Main.setBrand(Main.java:92)
at
$PropertyConduit_11258c2d0a9.set($PropertyConduit_11258c2d0a9.java)
at
org.apache.tapestry.internal.bindings.PropBinding.set(PropBinding.java:6
7)
... 48 more
-----Original Message-----
From: Howard Lewis Ship [mailto:[EMAIL PROTECTED]
Sent: Friday, May 04, 2007 2:32 PM
To: Tapestry users
Subject: Re: T5: SelectModel - a real world example
In your OptionModel, the label is the Brand description, and the value
is the Brand itself.
You then supply a ValueEncoder that converts between Brands and brand
ids (as strings, for the client side). If Brand is an entity object,
then it may be necessary to have the ValueEncoder talk to the database
or session store.
On 5/4/07, Joel Wiegman <[EMAIL PROTECTED]> wrote:
>
> Thanks for the reply Howard.
>
> >> The Select component doesn't know how to create a client-side
> representation of a Brand (it doesn't magically know to use the id).
>
> So, then... I guess my question would be... what is the
> BrandSelectModel for? In that object, I'm essentially mapping a
> Brand's "description" to the Brand object.
>
> Just curious what your thoughts are on that...
>
>
> -----Original Message-----
> From: Howard Lewis Ship [mailto:[EMAIL PROTECTED]
> Sent: Friday, May 04, 2007 1:42 PM
> To: Tapestry users
> Subject: Re: T5: SelectModel - a real world example
>
> In the simplest case, T5 thinks that the options in the drop down list
> are all strings.
>
> In your case, they are Brands. The Select component doesn't know how
> to create a client-side representation of a Brand (it doesn't
> magically know to use the id).
>
> You must provide a ValueEncoder that can convert between Brands and
> client-side string values. This is the encoder parameter of the
> Select component.
>
>
> On 5/4/07, Joel Wiegman <[EMAIL PROTECTED]> wrote:
> >
> > Not to be harsh, but I don't think I've ever written a select box
> > with
>
> > constant values (Enum). Seems like even Male/Female drop downs need
> > to be data-driven now-a-days. :->
> >
> > I've started to stub out a very simple "real world example" of a
> > select component in T5, but it doesn't appear to be as simple as I
> > thought it would be.
> >
> > A shiny nickel to anyone that can spot the flaw, because I sure
> can't...
> > I'm new to Tapestry in general so I could be missing something
> > really mundane here, but seems like it should work in my mind.
> >
> > Here are the players:
> >
> > << THE ERROR >>
> >
> > [ERROR] DefaultRequestExceptionHandler Processing of request failed
> > with uncaught exception: com.foo.data.Brand cannot be cast to
> > java.lang.String
> > java.lang.ClassCastException: com.foo.data.Brand cannot be cast to
> > java.lang.String
> > at
> >
> org.apache.tapestry.corelib.components.Select$1.toClient(Select.java:6
> 2)
> > at
> > org.apache.tapestry.corelib.components.Select.writeOptions(Select.ja
> > va
> > :1
> > 94)
> > at
> >
org.apache.tapestry.corelib.components.Select.options(Select.java:169)
> > at
> > org.apache.tapestry.corelib.components.Select.beforeRenderTemplate(S
> > el
> > ec
> > t.java)
> >
> >
> > << Main.html (abridged) >>
> >
> > <t:form>
> > <select t:type="select" t:id="brand" value="brand"
> > model="brandSelectModel"/>
> > </t:form>
> >
> >
> > << Main.java (abridged) >>
> >
> > package com.foo.pages;
> >
> > import com.foo.data.Brand;
> >
> > public class Main {
> >
> > private Brand brand;
> >
> > public Brand getBrand() {
> > return brand;
> > }
> >
> > public void setBrand(Brand brand) {
> > this.brand = brand;
> > }
> >
> > public BrandSelectModel getBrandSelectModel() {
> > return new BrandSelectModel(getBrands());
> > }
> >
> > public List<Brand> getBrands() {
> > List<Brand> brands = new ArrayList<Brand>();
> > brands.add(new Brand("1", "Brand 1"));
> > brands.add(new Brand("2", "Brand 2"));
> > brands.add(new Brand("3", "Brand 3"));
> > return brands;
> > }
> >
> > }
> >
> >
> > << Brand.java (abridged) >>
> >
> > package com.foo.data;
> >
> > public class Brand {
> >
> > private String id;
> > private String description;
> >
> > public Brand() {}
> >
> > public Brand(String id, String description) {
> > this.id = id;
> > this.description = description;
> > }
> >
> > public String getId() {
> > return id;
> > }
> >
> > public String getDescription() {
> > return description;
> > }
> >
> > }
> >
> >
> > << BrandSelectModel.java >>
> >
> > package com.foo.uisupport;
> >
> > import com.foo.data.Brand;
> >
> > public class BrandSelectModel implements SelectModel {
> >
> > private List<Brand> brands;
> >
> > public BrandSelectModel(List<Brand> brands) {
> > this.brands = brands;
> > }
> >
> > public List<OptionGroupModel> getOptionGroups() {
> > return null;
> > }
> >
> > public List<OptionModel> getOptions() {
> > List<OptionModel> optionModelList = new
> > ArrayList<OptionModel>();
> > for(Brand brand: brands) {
> > optionModelList.add(new
> > OptionModelImpl(brand.getDescription(), false, brand, new
String[0]));
> > }
> > return optionModelList;
> > }
> >
> > }
> >
> >
> >
> > --------------------------------------------------------------------
> > - To unsubscribe, e-mail: [EMAIL PROTECTED]
> > For additional commands, e-mail: [EMAIL PROTECTED]
> >
> >
>
>
> --
> Howard M. Lewis Ship
> TWD Consulting, Inc.
> Independent J2EE / Open-Source Java Consultant Creator and PMC Chair,
> Apache Tapestry Creator, Apache HiveMind
>
> Professional Tapestry training, mentoring, support and project work.
> http://howardlewisship.com
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: [EMAIL PROTECTED]
> For additional commands, e-mail: [EMAIL PROTECTED]
>
>
--
Howard M. Lewis Ship
TWD Consulting, Inc.
Independent J2EE / Open-Source Java Consultant Creator and PMC Chair,
Apache Tapestry Creator, Apache HiveMind
Professional Tapestry training, mentoring, support and project work.
http://howardlewisship.com
---------------------------------------------------------------------
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
--
Howard M. Lewis Ship
TWD Consulting, Inc.
Independent J2EE / Open-Source Java Consultant
Creator and PMC Chair, Apache Tapestry
Creator, Apache HiveMind
Professional Tapestry training, mentoring, support
and project work. http://howardlewisship.com
