Actually, the conversion of parameters is based on ValueEncoders. For
example, using tapestry-hibernate, Hibernate entities are expressed in
URLs as their primary key (usually a number). They are converted back
from strings to numbers to entities when the event handler method is
invoked.
The same approach can be applied to other domains. The
tapestry-hibernate code will give you an idea of how to do this.
Serializing POJOs into the URL is not a great idea; there's issues
with serialzing object graphs when you just want the object. T4 used
this approach, which led to endless discussions about how to get
Tapestry to *not* do that.
On Sun, Mar 23, 2008 at 2:40 PM, Yura Tkachenko
<[EMAIL PROTECTED]> wrote:
> Yes, I agree that for <a> tags Tapestry should pass data via URL. But in my
> example I'm using form component.
> <t:form t:id="userInputForm">
> <input type="text" t:id="theTextBox"/>
> <input type="submit" value="Submit"/>
> </t:form>
> As the result my form will be rendered into <form
> ...method=""POST>...</form> But even with that component when I'm passing
> some data during onSubmit event for form I'm getting such URL which contains
> encoded page activation context. I'm saying it not because I don't like long
> URLs. But if form already has an HTTP POST why not pass activation context
> as some parameter in this post request. In that case you won't have any
> limitation to the size of page activation context.
>
> Another concern is about type coercion.
> After trying to pass some object let's call it PageDataWrapper via
> activation context and implementing TypeCoercer for that particular object I
> realized that in big systems or big enterprise applications I might want to
> use different objects (different POJOs) as the result I should implement for
> each of this POJO TypeCoercer. But really POJO it's simply a Java Bean which
> eventually will be serialized/deserialized in TypeCoercer. So my question is
> why not have a rule in Typestry that each POJO which you wanna pass via Page
> Activation Context should implement Serializable interface and that's it.
> After that Typestry automatically will do coercion for serialized objects.
> Of course, some one can argue that you shouldn't pass big POJOs via
> activation context. But sometimes we need to pass data between pages using
> http request context, not http session.
>
> Thanks,
> Yura.
>
> On Sun, Mar 23, 2008 at 12:15 PM, Howard Lewis Ship <[EMAIL PROTECTED]>
> wrote:
>
>
>
> > Because the designers of HTML haven't figure out yet that an <a> tag
> > should have a method attribute, like a <form>.
> >
> > Also, the URLs should not be particularly long, as you should be
> > putting in just the ids of objects. If objects are showing up a long
> > MIME encoded serialized strings, you may want to rethink your
> > strategy.
> >
> > On Sun, Mar 23, 2008 at 11:24 AM, Yura Tkachenko
> > <[EMAIL PROTECTED]> wrote:
> > > Thank you Anton. Both solutions are works good for me. But still I have
> > a
> > > question why Tapestry 5 is generating long URL for activation context
> > > instead of sending these data using HTTP POST?
> > >
> > >
> > >
> > >
> > > On Sun, Mar 23, 2008 at 12:54 AM, Anton Litvinenko <
> > > [EMAIL PROTECTED]> wrote:
> > >
> > > > To pass more than parameter, a) from onPassivate method you should
> > > > return an object array:
> > > >
> > > > Object[] onPassivate() {
> > > > return new Object[] {getProductId(), "some string", true};
> > > > }
> > > >
> > > > b) Then you either define onActivate method as
> > > >
> > > > void onActivate(long productId, String xxx, Boolean yyy) {
> > > > setProductId(productId);
> > > > loadProduct();
> > > > }
> > > >
> > > > or
> > > >
> > > > void onActivate(Object[] context) {
> > > > Long projectId = Long.parseLong(((String) context[0]));
> > > > ....
> > > > }
> > > >
> > > > In case you decide to use the latter, then you should be aware that
> > > > context contains String representations of objects returned by
> > > > onPassivate.
> > > >
> > > > The second question: to pass your own value objects as context
> > > > parameters you should specify the strategy for converting your object
> > > > to string and restoring its state from the string (i.e. coercer) in
> > > > you AppModule. For instance to specify Date-to-String and
> > > > String-to-Date coercing you'd have to do the following:
> > > >
> > > > public static void
> > > > contributeTypeCoercer(Configuration<CoercionTuple> configuration) {
> > > > Coercion<Date, String> dateToString = new Coercion<Date,
> > String>()
> > > > {
> > > > public String coerce(Date date) {
> > > > return (new
> > > > SimpleDateFormat(DATETIME_PATTERN)).format(date);
> > > > }
> > > > };
> > > >
> > > > Coercion<String, Date> stringToDate = new Coercion<String,
> > Date>()
> > > > {
> > > > public Date coerce(String date) {
> > > > try {
> > > > return (new
> > > > SimpleDateFormat(DATETIME_PATTERN)).parse(date);
> > > > } catch (ParseException e) {
> > > > throw new RuntimeException("Coercion failed!", e);
> > > > }
> > > > }
> > > > };
> > > >
> > > > configuration.add(new CoercionTuple<Date, String>(Date.class,
> > > > String.class, dateToString));
> > > > configuration.add(new CoercionTuple<String,
> > > > Date>(String.class, Date.class, stringToDate));
> > > > }
> > > >
> > > > Check this for more:
> > > > http://tapestry.apache.org/tapestry5/tapestry-ioc/coerce.html
> > > >
> > > > Good luck!
> > > > Anton
> > > >
> > > > On Sun, Mar 23, 2008 at 8:32 AM, Yura Tkachenko
> > > > <[EMAIL PROTECTED]> wrote:
> > > > > And how I can pass more than one parameter? Or did you mean "I
> > cannot
> > > > pass
> > > > > more than one parameter"?
> > > > >
> > > > > Thanks,
> > > > > Yura.
> > > > >
> > > > >
> > > > >
> > > > > On Sat, Mar 22, 2008 at 10:46 PM, SergeEby <[EMAIL PROTECTED]>
> > wrote:
> > > > >
> > > > > >
> > > > > > Hi,
> > > > > >
> > > > > > You can pass more than one parameter.
> > > > > >
> > > > > > /Serge
> > > > > >
> > > > > >
> > > > > > Yura Tkachenko wrote:
> > > > > > >
> > > > > > > Hi All,
> > > > > > >
> > > > > > > I've been reading chapter about "Page Activation Context"
> > here:
> > > > > > >
> > > > http://tapestry.apache.org/tapestry5/tapestry-core/guide/pagenav.html
> > .
> > > > > > And
> > > > > > > I
> > > > > > > have a question: can I pass using activation context more than
> > one
> > > > > > > parameter?
> > > > > > >
> > > > > > > For example in help we have an example:
> > > > > > >
> > > > > > > void onActivate(long productId) {
> > > > > > > setProductId(productId);
> > > > > > > loadProduct();
> > > > > > > }
> > > > > > >
> > > > > > > long onPassivate() {
> > > > > > > return getProductId();
> > > > > > > }
> > > > > > >
> > > > > > > Also it was mentioned onPassivate method should be like a
> > mirror of
> > > > > > > onActivate. Does it means I can't pass more than one
> > parameter?
> > > > > > > Another approach I tried is it create another Java Bean
> > (wrapper
> > > > object)
> > > > > > > and
> > > > > > > simple try to pass this bean via activation context. In that
> > case
> > > > my
> > > > > > > onActivate and onPassivate were:
> > > > > > >
> > > > > > > void onActivate(PageWrapper wrappedData) {
> > > > > > > System.out.println("Activated with message: " +
> > > > wrappedData);
> > > > > > > setWrapper(wrappedData);
> > > > > > > }
> > > > > > >
> > > > > > > PageWrapper onPassivate() {
> > > > > > > System.out.println("Page is passivated.");
> > > > > > > return getWrapper();
> > > > > > > }
> > > > > > >
> > > > > > > As the result I got exception. From URL I understood that
> > Typestry
> > > > > > during
> > > > > > > passing parameter via activation context is converting it to
> > get
> > > > > > request.
> > > > > > > In
> > > > > > > my case for wrapped object URL was:
> > > > > > >
> > > > > >
> > > >
> >
> http://localhost:8080/t5first/second/com.packtpub.t5first.utils.PageWrapper%40307efc
> > > > > > > After looking to that URL I realized that T5 just call
> > toString of
> > > > > > passed
> > > > > > > object :-)
> > > > > > > So my additional questions:
> > > > > > > 1) Why not allow to user pass his own objects (POJO)?
> > > > > > > 2) Why not pass data via HTTP POST? Because as far as I know
> > HTTP
> > > > (at
> > > > > > > least
> > > > > > > some browsers and http servers) has some limitations to the
> > length
> > > > of
> > > > > > > URLs.
> > > > > > > Besides sooner or later some smart users will pass string with
> > a
> > > > few
> > > > > > > Kbytes
> > > > > > > and the page will get wrong data (truncated).
> > > > > > >
> > > > > > >
> > > > > >
> > > > > > --
> > > > > > View this message in context:
> > > > > >
> > > >
> >
> http://www.nabble.com/Page-activation-context-question-tp16231642p16231791.html
> > > > > > Sent from the Tapestry - User mailing list archive at Nabble.com
> > .
> > > > > >
> > > > > >
> > > > > >
> > ---------------------------------------------------------------------
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> > > > > > For additional commands, e-mail: [EMAIL PROTECTED]
> > > > > >
> > > > > >
> > > > >
> > > >
> > > >
> > > >
> > > > --
> > > > http://www.sourcekibitzer.org
> > > >
> > > > ---------------------------------------------------------------------
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> > > > For additional commands, e-mail: [EMAIL PROTECTED]
> > > >
> > > >
> > >
> >
> >
> >
> > --
> > Howard M. Lewis Ship
> >
> > Creator Apache Tapestry and Apache HiveMind
> >
> > ---------------------------------------------------------------------
> > To unsubscribe, e-mail: [EMAIL PROTECTED]
> > For additional commands, e-mail: [EMAIL PROTECTED]
> >
> >
>
--
Howard M. Lewis Ship
Creator Apache Tapestry and Apache HiveMind
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