My approach has to been to keep everything internal if possible. Thus an
interface is public, the implementation is internal.
If something is truly necessary, such as OptionModelImpl, there are two
approaches:
1) Make the implementation class public (possibly breaking existing code
that extends from the internal class) .... oh, and probably make it final as
well.
2) Define a public factory service for the implementation.
Right now, you can actually use the TypeCoercer as a kind of factory; if you
pass in a comma-separated string and ask for an SelectModel you'll get it.
Here, though, you're looking for something a little better adapted to your
entity classes. However, a bare-bones implementation of OptionModel (that
always returns false for isDisabled(), and null for getAttributes() ) is
only a couple of lines of code.
I think T4 fell into a trap of too much convenience stuff exposed as public
APIs. I would rather err on the side of over-zealousness for T5. You can
take internals public, but not the other way around, and once something is
public, it also is (or should be) final.
On 5/7/07, Bill Holloway <[EMAIL PROTECTED]> wrote:
I've written similar code -- while remembering that OptionModelImpl is
an "internal" class that Howard, in the documentation, has admonished
us not to use.
Community, what's the better solution?
Bill
On 5/7/07, Joel Wiegman <[EMAIL PROTECTED]> wrote:
> Eureka!
>
> Finally got it all working. What caused the drop down to not be
> defaulting is the fact that I declared my "Brand" list in two separate
> lists... One for the ValueEncoder and one for the SelectModel. Big no
> no! An "equals" is called on the value from the SelectModel and the
> value from the ValueEncoder, so if they are initialized as separate
> objects in separate lists the framework won't notice that they are equal
> (because they would point to a different memory location). I found that
> the framework also seems to like things better if the List of Brands is
> "@Persist"ed between pages. Here's the final source code that I used to
> get it all working (Enjoy!):
>
> Brand.java (simple POJO):
>
> 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;
> }
>
> }
>
>
> Test.java
>
> public class Test {
>
> @Persist
> private Brand brand;
>
> @Persist
> private List<Brand> brands;
>
> public Brand getBrand() {
> return brand;
> }
>
> public void setBrand(Brand brand) {
> this.brand = brand;
> }
>
> private List<Brand> getBrands()
> {
> if(brands == null) {
> 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"));
> brands.add(new Brand("4", "Brand 4"));
> }
>
> return brands;
> }
>
> public BrandSelectModel getBrandSelectModel() {
> return new BrandSelectModel(getBrands());
> }
>
> public BrandValueEncoder getBrandValueEncoder() {
> return new BrandValueEncoder(getBrands());
> }
>
> public class BrandValueEncoder implements ValueEncoder<Brand> {
>
> private List<Brand> brands;
>
> public BrandValueEncoder(List<Brand> brands) {
> this.brands = brands;
> }
>
> public String toClient(Brand brand) {
> return brand.getDescription();
> }
>
> public Brand toValue(String string) {
> for(Brand brand : brands) {
>
> if(brand.getDescription().equals(string)) {
> return brand;
> }
> }
> return null;
> }
>
> }
>
> 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;
> }
>
> }
>
> }
>
>
> Test.html
>
> <html xmlns:t="http://tapestry.apache.org/schema/tapestry_5_0_0.xsd";>
> <t:form>
>
> <select t:type="select" t:id="brand"
> value="brand" model="brandSelectModel"
> encoder="brandValueEncoder"
> onchange="this.form.submit();" />
>
> <br/>
>
> <t:if test="brand">
> ${brand.description}
> </t:if>
>
> </t:form>
> </html>
>
>
> -----Original Message-----
> From: Howard Lewis Ship [mailto:[EMAIL PROTECTED]
> Sent: Monday, May 07, 2007 12:17 PM
> To: Tapestry users
> Subject: Re: T5: SelectModel - a real world example
>
> Odd that you lost your value; the field is itself persistent (@Persist).
> Unless you are testing on a multi-machine cluster, you shouldn't see any
> problems along these lines!
>
> On 5/7/07, Joel Wiegman <[EMAIL PROTECTED]> wrote:
> >
> > Impressive! I was injecting that value via Spring to bootstrap it.
> > Makes sense I should have removed that...
> >
> > No errors now... However, the field doesn't appear to be binding on a
>
> > form submission. The encoder and the model appear to be receiving and
>
> > returning the correct values, the brand getter and setter appear to be
>
> > getting called, and the dropdown renders correctly except that it
> > always appears to be reset to the default value...
> >
> > I apologize for being so high-maintenance. If there is a working
> > example of a T5 binding select box anywhere on the web, please point
> > me there and I will leave you alone!
> >
> > Main.html
> >
> > <t:form>
> > <select t:type="select" class="mint_font_black_background"
> > t:id="brand"
> > value="brand" model="brandSelectModel" encoder="brandValueEncoder"
> > onchange="this.form.submit();" />
> > </t:form>
> >
> >
> > Main.java
> >
> > public class Main {
> >
> > @Inject
> > @SpringBean("enterprise")
> > private Enterprise enterprise;
> >
> > @Persist
> > private Brand brand;
> >
> > public Brand getBrand() {
> > return brand;
> > }
> >
> > public void setBrand(Brand brand) {
> > this.brand = brand;
> > }
> >
> > public BrandSelectModel getBrandSelectModel() {
> > return new BrandSelectModel(enterprise.getBrands());
> > }
> >
> > public BrandValueEncoder getBrandValueEncoder() {
> > return new BrandValueEncoder(enterprise.getBrands());
> > }
> >
> > public class BrandValueEncoder implements ValueEncoder<Brand>
> > {
> >
> > private List<Brand> brands;
> >
> > public BrandValueEncoder(List<Brand> brands) {
> > this.brands = brands;
> > }
> >
> > public String toClient(Brand brand) {
> > return brand.getDescription();
> > }
> >
> > public Brand toValue(String string) {
> > for(Brand brand : brands) {
> >
> > if(brand.getDescription().equals(string)) {
> > return brand;
> > }
> > }
> > return null;
> > }
> >
> > }
> >
> > 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;
> > }
> >
> > }
> >
> > }
> >
> >
> >
> > -----Original Message-----
> > From: Howard Lewis Ship [mailto:[EMAIL PROTECTED]
> > Sent: Saturday, May 05, 2007 9:45 PM
> > To: Tapestry users
> > Subject: Re: T5: SelectModel - a real world example
> >
> > 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.hand
> > > le
> > > Ev
> > > ent(ComponentPageElementImpl.java:903)
> > > at
> > > org.apache.tapestry.internal.structure.ComponentPageElementImpl.trig
> > > ge
> > > rE
> > > vent(ComponentPageElementImpl.java:1002)
> > > at
> > > org.apache.tapestry.internal.services.ActionLinkHandlerImpl.handle(A
> > > ct
> > > io
> > > nLinkHandlerImpl.java:100)
> > > at
> > > org.apache.tapestry.internal.services.ActionLinkHandlerImpl.handle(A
> > > ct
> > > io
> > > nLinkHandlerImpl.java:53)
> > > at
> > > $ActionLinkHandler_11258c2d07d.handle($ActionLinkHandler_11258c2d07d
> > > .j
> > > av
> > > a)
> > > at
> > > org.apache.tapestry.internal.services.ComponentActionDispatcher.disp
> > > at
> > > ch
> > > (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_val
> > > ue
> > > _0
> > > (Select.java)
> > > at
> > > org.apache.tapestry.corelib.components.Select.processSubmission(Sele
> > > ct
> > > .j
> > > ava:238)
> > > at
> > > org.apache.tapestry.corelib.base.AbstractField.processSubmission(Abs
> > > tr
> > > ac
> > > tField.java:210)
> > > at
> > >
> >
> org.apache.tapestry.corelib.base.AbstractField.access$100(AbstractField.
> > > java:47)
> > > at
> > > org.apache.tapestry.corelib.base.AbstractField$ProcessSubmissionActi
> > > on
> > > .e
> > > xecute(AbstractField.java:116)
> > > at
> > > org.apache.tapestry.corelib.base.AbstractField$ProcessSubmissionActi
> > > on
> > > .e
> > > xecute(AbstractField.java:110)
> > > at
> > > org.apache.tapestry.corelib.components.Form.onAction(Form.java:347)
> > > ... 40 more
> > > Caused by: org.apache.tapestry.ioc.internal.util.TapestryException:
> > > Field com.foo.pages.Main.brand is read-only. [at
> context:WEB-INF/Main.
> > > html, line 89, column 278]
> > > at
> > > org.apache.tapestry.internal.bindings.PropBinding.set(PropBinding.ja
> > > va
> > > :7
> > > 1)
> > > at
> > >
> org.apache.tapestry.internal.structure.InternalComponentResourcesImpl.
> > > wr
> > > iteParameter(InternalComponentResourcesImpl.java:219)
> > > ... 47 more
> > > Caused by: java.lang.RuntimeException: Field
> > > com.foo.pages.Main.brand is read-only.
> > > at com.foo.pages.Main._$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.ja
> > > va
> > > :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.ja
> > > > va
> > > > :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:16
> > > 9)
> > > > > at
> > > > > org.apache.tapestry.corelib.components.Select.beforeRenderTempla
> > > > > te
> > > > > (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
> >
> > ---------------------------------------------------------------------
> > 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]
>
>
--
"The future is here. It's just not evenly distributed yet."
-- Traditional
---------------------------------------------------------------------
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
