2:54 p.m.
So here's one of those, "why is this different than that?" questions:
Unless I'm mistaken, ui:repeat is not a component and therefore cannot
be bound to a backing bean, but -- would it make sense to support
something *like* <h:dataTable> in order to support determining the
selected row on action events and value change events? A component that
would privide a bindable DataModel / List<Object> row access like
<h:dataTable>?
My use case is this:
* Managed Bean contains a List of objects
* Each object rendered to screen with input field
* User submits the input field (with a command link or button,
etc)
* ManagedBean needs to take action on the appropriate row values
I have a list of objects - I need to render them onto the screen (not
necessarily in an HTML table, maybe a <ul> would be nicer) but I can't
use <ui:repeat> because each row has a commandLink, and I need to be
able to determine which row the user clicked on in order to take the
appropriate action.
EL2 helps with this, but... now what if I have a ValueChangeEvent for an
input field on each <li> row? Now I can no longer use EL2 to pass the
row into the ValueChangeListener, and I would have to use something like
<f:setPropertyActionListener> which is not only getting increasingly
complicated, but I'd also have to set an attribute insidethe VCL itself,
or in a bean VCL knows about - then referencing it - which is terribly
ugly. Now try to fit all that into a composite component and it gets
really ugly to try attaching tons of VCLs or ALs or SPALs to values
inside the component.
Am I attacking this problem in the wrong way? Is this one of those
things that has an easy solution I'm not seeing? Or is this a genuine
gap?
--Lincoln
1:38 p.m.
Lincoln,
There is an approach which will work in this case, but it doesn't rule out
the possibility that refinement is needed. Let me open with the example.
On the home page, there is a link that will load a feature list and navigate
to the list page.
/home.xhtml
<h:form>
<h:commandButton action="#{featureList.load}" value="View feature
list"/>
</h:form>
/list.xhtml
<h:form>
<ul>
<ui:repeat var="f" value="#{featureList.features}">
<h:inputText value="#{f.name}"/> <h:commandButton
action="#{featureList.action}" value="Action"/>
</ui:repeat>
</ul>
</h:form>
And finally, the controller:
@ManagedBean
@SessionScoped // chosen for convenience, really it should be view-scoped or
conversation-scoped (299)
public class FeatureList
{
private DataModel features;
public DataModel getFeatures() { return features; }
public String load() {
List<Feature> l = new ArrayList<Feature>();
l.add(new Feature("One"));
l.add(new Feature("Two"));
features = new ListDataModel(l);
}
public void action()
{
System.out.println("You clicked on the button in the row with
feature " + ((Feature) features.getRowData()).getName());
}
}
Note that the getRowData() method is positioned at the row which received
the action during the invocation of any listener. Be careful, though,
because it points to the first row if no row is selected. First check if
getRowIndex() >= 0 to see if a row received an action.
Regardless, this is still a horrible way (IMO) of having to select the row.
It is very opaque. This is one area where you really take Seam for granted
because you would instead use injection of the selected row:
@DataModelSelection Feature selectedFeature;
There may be some edge cases where this doesn't work. Please apply to your
use case and report back any gaps.
-Dan
--
Dan Allen
Senior Software Engineer, Red Hat | Author of Seam in Action
Registered Linux User #231597
http://mojavelinux.com
http://mojavelinux.com/seaminaction
http://in.relation.to/Bloggers/Dan
1:31 a.m.
Hi Lincoln,
Unless I'm mistaken, ui:repeat is not a component and therefore
cannot
be bound to a backing bean,
I thought it was - and just checked, it derives from UIComponentBase.
Does the binding attribute not work for you?
EL2 helps with this, but... now what if I have a ValueChangeEvent for
an
input field on each <li> row? Now I can no longer use EL2 to pass the
row into the ValueChangeListener
why not? <h:inputText
valueChangeListener="#{myBean.valueChangeListener(listItem)}"/> should
work in the next EL version respectively the JBoss EL, right?
regards,
Martin
12:45 p.m.
> EL2 helps with this, but... now what if I have a ValueChangeEvent for an
> input field on each <li> row? Now I can no longer use EL2 to pass the
> row into the ValueChangeListener
why not? <h:inputText
valueChangeListener="#{myBean.valueChangeListener(listItem)}"/> should
work in the next EL version respectively the JBoss EL, right?
In theory. Someone should check this because there are two things happening
here:
- Optional no-arguments method for ValueChangeListener
- Parametrized method in EL
Granted, in this case you aren't going to get the ValueChangeEvent argument
because you are opting to not accept it. Does that sound right?
-Dan
--
Dan Allen
Senior Software Engineer, Red Hat | Author of Seam in Action
Registered Linux User #231597
http://mojavelinux.com
http://mojavelinux.com/seaminaction
http://in.relation.to/Bloggers/Dan
5:26 p.m.
Hi Dan,
I did a little research, and it won't work. Therefore I just sent a
mail out to the JSR-245 spec lead asking for the following signature
in the EL-resolver - that might help at least a little in providing
such functionality. And I thought we had discussed that this should
work at some point of time.
public Object invoke(ELContext context,
Object base,
Object method,
Class[] formalParamTypes,
Object[] formalParams,
Class[] parsedParamTypes,
Object[] parsedParams
) {
...
}
regards,
Martin
On 8/7/09, Dan Allen <dan.j.allen(a)gmail.com> wrote:
>
> > EL2 helps with this, but... now what if I have a ValueChangeEvent for an
> > input field on each <li> row? Now I can no longer use EL2 to pass the
> > row into the ValueChangeListener
>
> why not? <h:inputText
> valueChangeListener="#{myBean.valueChangeListener(listItem)}"/> should
> work in the next EL version respectively the JBoss EL, right?
In theory. Someone should check this because there are two things happening
here:
- Optional no-arguments method for ValueChangeListener
- Parametrized method in EL
Granted, in this case you aren't going to get the ValueChangeEvent argument
because you are opting to not accept it. Does that sound right?
-Dan
--
Dan Allen
Senior Software Engineer, Red Hat | Author of Seam in Action
Registered Linux User #231597
http://mojavelinux.com
http://mojavelinux.com/seaminaction
http://in.relation.to/Bloggers/Dan
--
http://www.irian.at
Your JSF powerhouse -
JSF Consulting, Development and
Courses in English and German
Professional Support for Apache MyFaces
4:14 p.m.
ui:repeat is a normal JSF component that supports binding but
<c:forEach> is compilation directive only that has no component
associated with tag.
The question just recalls me one forgotten problem: h:dataTable and
ui:repeat is complete different components that doing similar jobs.
While ui:repeat knows about UIDataTable and works well inside it,
DataTable itself has no clue what UIRepeat is iteration component,
therefore rendering a set of tables using ui:repeat is not possible.
On 08/03/2009 12:54 PM, Lincoln Baxter, III wrote:
So here's one of those, "why is this different than
that?" questions:
Unless I'm mistaken, ui:repeat is not a component and therefore cannot
be bound to a backing bean, but -- would it make sense to support
something *like* <h:dataTable> in order to support determining the
selected row on action events and value change events? A component that
would privide a bindable DataModel / List<Object> row access like
<h:dataTable>?
*My use case is this:*
* Managed Bean contains a List of objects
* Each object rendered to screen with input field
* User submits the input field (with a command link or button, etc)
* ManagedBean needs to take action on the appropriate row values
I have a list of objects - I need to render them onto the screen (not
necessarily in an HTML table, maybe a <ul> would be nicer) but I can't
use <ui:repeat> because each row has a commandLink, and I need to be
able to determine which row the user clicked on in order to take the
appropriate action.
EL2 helps with this, but... now what if I have a ValueChangeEvent for an
input field on each <li> row? Now I can no longer use EL2 to pass the
row into the ValueChangeListener, and I would have to use something like
<f:setPropertyActionListener> which is not only getting increasingly
complicated, but I'd also have to set an attribute /inside/the VCL
itself, or in a bean VCL knows about - then referencing it - which is
terribly ugly. Now try to fit all that into a composite component and it
gets really ugly to try attaching tons of VCLs or ALs or SPALs to values
inside the component.
Am I attacking this problem in the wrong way? Is this one of those
things that has an easy solution I'm not seeing? Or is this a genuine gap?
--Lincoln
5:31 p.m.
Ok, so perhaps I should explain my dataTable/ui:repeat use case a little
bit more, since it seems like some of these options are not going very
smoothly for me. I've labeled 3 questions, just to keep this long
message slightly more organized.
The Scenario:
-----------------------------------------------------------------------
Everything on your website is RequestScoped -- There are no stateful
pages or SessionScoped beans whatsoever. That means that data is loaded
every time a user accesses a page via GET, POST, etc... if an ajax event
on a page updates some value - it actually needs to be updated via a
service call on the back-end.
You have an Object: "Task" -- a Task has an Assignee, a few Dates, and a
Status.
In order to keep the look and feel of Tasks consistent on the UI, you've
created a "taskBlock.xhtml" composite component to handle the layout.
However -- you would like inline editing and updating of the Task data
to work via Ajax.
Each taskBlock component instance needs to be able to save, delete its
given Task object instance. Hence, you need:
* a delete(Task) action to occur on a commandButton action event (this
part is easy thanks to JBoss Seam/EL2)
* a save(Task) method to be called on a ValueChangeEvent for each
editable field
The latter is the hard part, because the task object may have come from
a list, it may have been passed in by itself. A workaround would be to
have a "Save" button, but that's an extra click for the user, and ugly,
etc, lots of reasons why you wouldn't want this. ValueChanceListeners do
not accept properties, or allow user-specified ValueChange Methods to be
supplied.
Solutions?
-----------------------------------------------------------------------
I tried including a hidden commandLink in the Ajax execute="" attribute
in order to trigger the action after the ValueChangeEvent, but it never
fires -- not sure if that's a bug or intended.
**Question 1: Almost every AJAX framework I know of allows you to simply
execute a method on the server side, with or without params, and return
a result... is this possible with JSF's Ajax framework?
What would be optimal, would be if you could supply, as mentioned in a
previous message in this chain, a ValueChangeMethod:
<h:inputText>
<f:valueChangeMethod method="saveTask(t)" />
</h:inputText>
or
<f:valueChangeMethod method="saveTask(event, t)" />
Which is even more powerful if you consider the new EL, or JBoss EL. If
the method contains a "ValueChangeEvent event" in the method signature,
it should be injected into the call.
Thus, you would not have to write extra classes, or bind any objects, or
retrieve any rows from a DataModel or DataTable.
**Question 2: Without changing the Spec, how would you achieve this and
ensure the user interaction is the same? The value needs to be saved via
Ajax when they change it on the UI... without clicking a save button. If
there is no way to support this type of functionality in the spec
currently, then I propose we add it.
**Question 3: Is this really an uncommon use case? Does everyone make a
separate view/edit page for lists of items?
The UI JavaScript, CSS, and HTML is not my strong point -- perhaps a
component writer would invest more time with JSF's Ajax JavaScript in
order to get the behavior right via custom JS, CS, and HTML..?
I'm basically trying to figure out if I'm way off base here, and need a
paradigm readjustment. It seems like nobody else is raising issues like
this online, so it's possible that JSF doesn't need to change; I'd just
like to know what everyone else is eating before I push for a change ;)
--Lincoln
On Fri, 2009-08-07 at 14:14 -0700, Alexander Smirnov wrote:
ui:repeat is a normal JSF component that supports binding but
<c:forEach> is compilation directive only that has no component
associated with tag.
The question just recalls me one forgotten problem: h:dataTable and
ui:repeat is complete different components that doing similar jobs.
While ui:repeat knows about UIDataTable and works well inside it,
DataTable itself has no clue what UIRepeat is iteration component,
therefore rendering a set of tables using ui:repeat is not possible.
On 08/03/2009 12:54 PM, Lincoln Baxter, III wrote:
> So here's one of those, "why is this different than that?" questions:
>
> Unless I'm mistaken, ui:repeat is not a component and therefore cannot
> be bound to a backing bean, but -- would it make sense to support
> something *like* <h:dataTable> in order to support determining the
> selected row on action events and value change events? A component that
> would privide a bindable DataModel / List<Object> row access like
> <h:dataTable>?
>
> *My use case is this:*
>
> * Managed Bean contains a List of objects
> * Each object rendered to screen with input field
> * User submits the input field (with a command link or button, etc)
> * ManagedBean needs to take action on the appropriate row values
>
>
> I have a list of objects - I need to render them onto the screen (not
> necessarily in an HTML table, maybe a <ul> would be nicer) but I can't
> use <ui:repeat> because each row has a commandLink, and I need to be
> able to determine which row the user clicked on in order to take the
> appropriate action.
>
> EL2 helps with this, but... now what if I have a ValueChangeEvent for an
> input field on each <li> row? Now I can no longer use EL2 to pass the
> row into the ValueChangeListener, and I would have to use something like
> <f:setPropertyActionListener> which is not only getting increasingly
> complicated, but I'd also have to set an attribute /inside/the VCL
> itself, or in a bean VCL knows about - then referencing it - which is
> terribly ugly. Now try to fit all that into a composite component and it
> gets really ugly to try attaching tons of VCLs or ALs or SPALs to values
> inside the component.
>
> Am I attacking this problem in the wrong way? Is this one of those
> things that has an easy solution I'm not seeing? Or is this a genuine gap?
>
> --Lincoln
>
>
6:10 p.m.
IMO this is not an uncommon use case, and we should support via (1)
On 12 Aug 2009, at 23:31, Lincoln Baxter, III wrote:
Ok, so perhaps I should explain my dataTable/ui:repeat use case a
little bit more, since it seems like some of these options are not
going very smoothly for me. I've labeled 3 questions, just to keep
this long message slightly more organized.
The Scenario:
-----------------------------------------------------------------------
Everything on your website is RequestScoped -- There are no stateful
pages or SessionScoped beans whatsoever. That means that data is
loaded every time a user accesses a page via GET, POST, etc... if an
ajax event on a page updates some value - it actually needs to be
updated via a service call on the back-end.
You have an Object: "Task" -- a Task has an Assignee, a few Dates,
and a Status.
In order to keep the look and feel of Tasks consistent on the UI,
you've created a "taskBlock.xhtml" composite component to handle the
layout. However -- you would like inline editing and updating of the
Task data to work via Ajax.
Each taskBlock component instance needs to be able to save, delete
its given Task object instance. Hence, you need:
* a delete(Task) action to occur on a commandButton action event
(this part is easy thanks to JBoss Seam/EL2)
* a save(Task) method to be called on a ValueChangeEvent for each
editable field
The latter is the hard part, because the task object may have come
from a list, it may have been passed in by itself. A workaround
would be to have a "Save" button, but that's an extra click for the
user, and ugly, etc, lots of reasons why you wouldn't want this.
ValueChanceListeners do not accept properties, or allow user-
specified ValueChange Methods to be supplied.
Solutions?
-----------------------------------------------------------------------
I tried including a hidden commandLink in the Ajax execute=""
attribute in order to trigger the action after the ValueChangeEvent,
but it never fires -- not sure if that's a bug or intended.
**Question 1: Almost every AJAX framework I know of allows you to
simply execute a method on the server side, with or without params,
and return a result... is this possible with JSF's Ajax framework?
What would be optimal, would be if you could supply, as mentioned in
a previous message in this chain, a ValueChangeMethod:
<h:inputText>
<f:valueChangeMethod method="saveTask(t)" />
</h:inputText>
or
<f:valueChangeMethod method="saveTask(event, t)" />
Which is even more powerful if you consider the new EL, or JBoss EL.
If the method contains a "ValueChangeEvent event" in the method
signature, it should be injected into the call.
Thus, you would not have to write extra classes, or bind any
objects, or retrieve any rows from a DataModel or DataTable.
**Question 2: Without changing the Spec, how would you achieve this
and ensure the user interaction is the same? The value needs to be
saved via Ajax when they change it on the UI... without clicking a
save button. If there is no way to support this type of
functionality in the spec currently, then I propose we add it.
**Question 3: Is this really an uncommon use case? Does everyone
make a separate view/edit page for lists of items?
The UI JavaScript, CSS, and HTML is not my strong point -- perhaps a
component writer would invest more time with JSF's Ajax JavaScript
in order to get the behavior right via custom JS, CS, and HTML..?
I'm basically trying to figure out if I'm way off base here, and
need a paradigm readjustment. It seems like nobody else is raising
issues like this online, so it's possible that JSF doesn't need to
change; I'd just like to know what everyone else is eating before I
push for a change ;)
--Lincoln
On Fri, 2009-08-07 at 14:14 -0700, Alexander Smirnov wrote:
>
> ui:repeat is a normal JSF component that supports binding but
> <c:forEach> is compilation directive only that has no component
> associated with tag.
> The question just recalls me one forgotten problem: h:dataTable and
> ui:repeat is complete different components that doing similar jobs.
> While ui:repeat knows about UIDataTable and works well inside it,
> DataTable itself has no clue what UIRepeat is iteration component,
> therefore rendering a set of tables using ui:repeat is not possible.
>
>
> On 08/03/2009 12:54 PM, Lincoln Baxter, III wrote:
> > So here's one of those, "why is this different than that?"
> questions:
> >
> > Unless I'm mistaken, ui:repeat is not a component and therefore
> cannot
> > be bound to a backing bean, but -- would it make sense to support
> > something *like* <h:dataTable> in order to support determining the
> > selected row on action events and value change events? A
> component that
> > would privide a bindable DataModel / List<Object> row access like
> > <h:dataTable>?
> >
> > *My use case is this:*
> >
> > * Managed Bean contains a List of objects
> > * Each object rendered to screen with input field
> > * User submits the input field (with a command link or
> button, etc)
> > * ManagedBean needs to take action on the appropriate row
> values
> >
> >
> > I have a list of objects - I need to render them onto the screen
> (not
> > necessarily in an HTML table, maybe a <ul> would be nicer) but I
> can't
> > use <ui:repeat> because each row has a commandLink, and I need to
> be
> > able to determine which row the user clicked on in order to take
> the
> > appropriate action.
> >
> > EL2 helps with this, but... now what if I have a ValueChangeEvent
> for an
> > input field on each <li> row? Now I can no longer use EL2 to pass
> the
> > row into the ValueChangeListener, and I would have to use
> something like
> > <f:setPropertyActionListener> which is not only getting
> increasingly
> > complicated, but I'd also have to set an attribute /inside/the VCL
> > itself, or in a bean VCL knows about - then referencing it -
> which is
> > terribly ugly. Now try to fit all that into a composite component
> and it
> > gets really ugly to try attaching tons of VCLs or ALs or SPALs to
> values
> > inside the component.
> >
> > Am I attacking this problem in the wrong way? Is this one of those
> > things that has an easy solution I'm not seeing? Or is this a
> genuine gap?
> >
> > --Lincoln
> >
> >
6:45 p.m.
my +1.
2 steps:
1) add a method-attribute to the f:valueChangeListener-tag
2) get Unified-EL to also support passing the formal parameters (see
my mail to the spec lead)
with that, everything should be sorted.
regards,
Martin
On 8/13/09, Pete Muir <pmuir(a)redhat.com> wrote:
IMO this is not an uncommon use case, and we should support via (1)
On 12 Aug 2009, at 23:31, Lincoln Baxter, III wrote:
> Ok, so perhaps I should explain my dataTable/ui:repeat use case a
> little bit more, since it seems like some of these options are not
> going very smoothly for me. I've labeled 3 questions, just to keep
> this long message slightly more organized.
>
> The Scenario:
> -----------------------------------------------------------------------
>
> Everything on your website is RequestScoped -- There are no stateful
> pages or SessionScoped beans whatsoever. That means that data is
> loaded every time a user accesses a page via GET, POST, etc... if an
> ajax event on a page updates some value - it actually needs to be
> updated via a service call on the back-end.
>
> You have an Object: "Task" -- a Task has an Assignee, a few Dates,
> and a Status.
>
> In order to keep the look and feel of Tasks consistent on the UI,
> you've created a "taskBlock.xhtml" composite component to handle the
> layout. However -- you would like inline editing and updating of the
> Task data to work via Ajax.
>
> Each taskBlock component instance needs to be able to save, delete
> its given Task object instance. Hence, you need:
>
> * a delete(Task) action to occur on a commandButton action event
> (this part is easy thanks to JBoss Seam/EL2)
> * a save(Task) method to be called on a ValueChangeEvent for each
> editable field
>
> The latter is the hard part, because the task object may have come
> from a list, it may have been passed in by itself. A workaround
> would be to have a "Save" button, but that's an extra click for the
> user, and ugly, etc, lots of reasons why you wouldn't want this.
> ValueChanceListeners do not accept properties, or allow user-
> specified ValueChange Methods to be supplied.
>
> Solutions?
> -----------------------------------------------------------------------
>
> I tried including a hidden commandLink in the Ajax execute=""
> attribute in order to trigger the action after the ValueChangeEvent,
> but it never fires -- not sure if that's a bug or intended.
>
> **Question 1: Almost every AJAX framework I know of allows you to
> simply execute a method on the server side, with or without params,
> and return a result... is this possible with JSF's Ajax framework?
>
> What would be optimal, would be if you could supply, as mentioned in
> a previous message in this chain, a ValueChangeMethod:
>
> <h:inputText>
> <f:valueChangeMethod method="saveTask(t)" />
> </h:inputText>
>
> or
>
> <f:valueChangeMethod method="saveTask(event, t)" />
>
> Which is even more powerful if you consider the new EL, or JBoss EL.
> If the method contains a "ValueChangeEvent event" in the method
> signature, it should be injected into the call.
>
> Thus, you would not have to write extra classes, or bind any
> objects, or retrieve any rows from a DataModel or DataTable.
>
> **Question 2: Without changing the Spec, how would you achieve this
> and ensure the user interaction is the same? The value needs to be
> saved via Ajax when they change it on the UI... without clicking a
> save button. If there is no way to support this type of
> functionality in the spec currently, then I propose we add it.
>
> **Question 3: Is this really an uncommon use case? Does everyone
> make a separate view/edit page for lists of items?
>
> The UI JavaScript, CSS, and HTML is not my strong point -- perhaps a
> component writer would invest more time with JSF's Ajax JavaScript
> in order to get the behavior right via custom JS, CS, and HTML..?
>
> I'm basically trying to figure out if I'm way off base here, and
> need a paradigm readjustment. It seems like nobody else is raising
> issues like this online, so it's possible that JSF doesn't need to
> change; I'd just like to know what everyone else is eating before I
> push for a change ;)
>
> --Lincoln
>
>
> On Fri, 2009-08-07 at 14:14 -0700, Alexander Smirnov wrote:
>>
>> ui:repeat is a normal JSF component that supports binding but
>> <c:forEach> is compilation directive only that has no component
>> associated with tag.
>> The question just recalls me one forgotten problem: h:dataTable and
>> ui:repeat is complete different components that doing similar jobs.
>> While ui:repeat knows about UIDataTable and works well inside it,
>> DataTable itself has no clue what UIRepeat is iteration component,
>> therefore rendering a set of tables using ui:repeat is not possible.
>>
>>
>> On 08/03/2009 12:54 PM, Lincoln Baxter, III wrote:
>> > So here's one of those, "why is this different than that?"
>> questions:
>> >
>> > Unless I'm mistaken, ui:repeat is not a component and therefore
>> cannot
>> > be bound to a backing bean, but -- would it make sense to support
>> > something *like* <h:dataTable> in order to support determining the
>> > selected row on action events and value change events? A
>> component that
>> > would privide a bindable DataModel / List<Object> row access like
>> > <h:dataTable>?
>> >
>> > *My use case is this:*
>> >
>> > * Managed Bean contains a List of objects
>> > * Each object rendered to screen with input field
>> > * User submits the input field (with a command link or
>> button, etc)
>> > * ManagedBean needs to take action on the appropriate row
>> values
>> >
>> >
>> > I have a list of objects - I need to render them onto the screen
>> (not
>> > necessarily in an HTML table, maybe a <ul> would be nicer) but I
>> can't
>> > use <ui:repeat> because each row has a commandLink, and I need to
>> be
>> > able to determine which row the user clicked on in order to take
>> the
>> > appropriate action.
>> >
>> > EL2 helps with this, but... now what if I have a ValueChangeEvent
>> for an
>> > input field on each <li> row? Now I can no longer use EL2 to pass
>> the
>> > row into the ValueChangeListener, and I would have to use
>> something like
>> > <f:setPropertyActionListener> which is not only getting
>> increasingly
>> > complicated, but I'd also have to set an attribute /inside/the VCL
>> > itself, or in a bean VCL knows about - then referencing it -
>> which is
>> > terribly ugly. Now try to fit all that into a composite component
>> and it
>> > gets really ugly to try attaching tons of VCLs or ALs or SPALs to
>> values
>> > inside the component.
>> >
>> > Am I attacking this problem in the wrong way? Is this one of those
>> > things that has an easy solution I'm not seeing? Or is this a
>> genuine gap?
>> >
>> > --Lincoln
>> >
>> >
--
http://www.irian.at
Your JSF powerhouse -
JSF Consulting, Development and
Courses in English and German
Professional Support for Apache MyFaces
6:38 p.m.
Maybe I'm dense. OK, probably I'm dense, but if you're passing a Task
object into the composite component, why not have that object also have
the save and delete method on it? There's no need for a method to have
a parameter if it's already a part of the object it acts on.
So, instead of delete(task), you'd have task.delete(). Isn't that
possible?
Then, you should be able to use those passed methods as your action and
valueChange targets right?
What am I missing?
Jim
P.S. Not that it wouldn't be handy to execute arbitrary methods on the
server - in one of my examples (poll, I think), I did resort to a hidden
button that I call click() on to do just that. Icky.
On 8/12/09 3:31 PM, Lincoln Baxter, III wrote:
Ok, so perhaps I should explain my dataTable/ui:repeat use case a
little
bit more, since it seems like some of these options are not going very
smoothly for me. I've labeled 3 questions, just to keep this long
message slightly more organized.
*The Scenario:*
-----------------------------------------------------------------------
Everything on your website is RequestScoped -- There are no stateful
pages or SessionScoped beans whatsoever. That means that data is loaded
every time a user accesses a page via GET, POST, etc... if an ajax event
on a page updates some value - it actually needs to be updated via a
service call on the back-end.
You have an Object: "Task" -- a Task has an Assignee, a few Dates, and a
Status.
In order to keep the look and feel of Tasks consistent on the UI, you've
created a "taskBlock.xhtml" composite component to handle the layout.
However -- you would like inline editing and updating of the Task data
to work via Ajax.
Each taskBlock component instance needs to be able to save, delete its
given Task object instance. Hence, you need:
* a delete(Task) action to occur on a commandButton action event (this
part is easy thanks to JBoss Seam/EL2)
* a save(Task) method to be called on a ValueChangeEvent for each
editable field
The latter is the hard part, because the task object may have come from
a list, it may have been passed in by itself. A workaround would be to
have a "Save" button, but that's an extra click for the user, and ugly,
etc, lots of reasons why you wouldn't want this. ValueChanceListeners do
not accept properties, or allow user-specified ValueChange Methods to be
supplied.
*Solutions?*
-----------------------------------------------------------------------
I tried including a hidden commandLink in the Ajax execute="" attribute
in order to trigger the action after the ValueChangeEvent, but it never
fires -- not sure if that's a bug or intended.
***Question 1: *Almost every AJAX framework I know of allows you to
simply execute a method on the server side, with or without params, and
return a result... is this possible with JSF's Ajax framework?
What would be optimal, would be if you could supply, as mentioned in a
previous message in this chain, a ValueChangeMethod:
<h:inputText>
<f:valueChangeMethod method="saveTask(t)" />
</h:inputText>
or
<f:valueChangeMethod method="saveTask(event, t)" />
Which is even more powerful if you consider the new EL, or JBoss EL. If
the method contains a "ValueChangeEvent event" in the method signature,
it should be injected into the call.
Thus, you would not have to write extra classes, or bind any objects, or
retrieve any rows from a DataModel or DataTable.
***Question 2:* Without changing the Spec, how would you achieve this
and ensure the user interaction is the same? The value needs to be saved
via Ajax when they change it on the UI... without clicking a save
button. If there is no way to support this type of functionality in the
spec currently, then I propose we add it.
***Question 3:* Is this really an uncommon use case? Does everyone make
a separate view/edit page for lists of items?
The UI JavaScript, CSS, and HTML is not my strong point -- perhaps a
component writer would invest more time with JSF's Ajax JavaScript in
order to get the behavior right via custom JS, CS, and HTML..?
I'm basically trying to figure out if I'm way off base here, and need a
paradigm readjustment. It seems like nobody else is raising issues like
this online, so it's possible that JSF doesn't need to change; I'd just
like to know what everyone else is eating before I push for a change ;)
--Lincoln
On Fri, 2009-08-07 at 14:14 -0700, Alexander Smirnov wrote:
> ui:repeat is a normal JSF component that supports binding but
> <c:forEach> is compilation directive only that has no component
> associated with tag.
> The question just recalls me one forgotten problem: h:dataTable and
> ui:repeat is complete different components that doing similar jobs.
> While ui:repeat knows about UIDataTable and works well inside it,
> DataTable itself has no clue what UIRepeat is iteration component,
> therefore rendering a set of tables using ui:repeat is not possible.
>
>
> On 08/03/2009 12:54 PM, Lincoln Baxter, III wrote:
> > So here's one of those,"why is this different than that?"
questions:
> >
> > Unless I'm mistaken, ui:repeat is not a component and therefore cannot
> > be bound to a backing bean, but -- would it make sense to support
> > something *like*<h:dataTable> in order to support determining the
> > selected row on action events and value change events? A component that
> > would privide a bindable DataModel / List<Object> row access like
> > <h:dataTable>?
> >
> > *My use case is this:*
> >
> > * Managed Bean contains a List of objects
> > * Each object rendered to screen with input field
> > * User submits the input field (with a command link or button, etc)
> > * ManagedBean needs to take action on the appropriate row values
> >
> >
> > I have a list of objects - I need to render them onto the screen (not
> > necessarily in an HTML table, maybe a<ul> would be nicer) but I
can't
> > use<ui:repeat> because each row has a commandLink, and I need to be
> > able to determine which row the user clicked on in order to take the
> > appropriate action.
> >
> > EL2 helps with this, but... now what if I have a ValueChangeEvent for an
> > input field on each<li> row? Now I can no longer use EL2 to pass the
> > row into the ValueChangeListener, and I would have to use something like
> > <f:setPropertyActionListener> which is not only getting increasingly
> > complicated, but I'd also have to set an attribute /inside/the VCL
> > itself, or in a bean VCL knows about - then referencing it - which is
> > terribly ugly. Now try to fit all that into a composite component and it
> > gets really ugly to try attaching tons of VCLs or ALs or SPALs to values
> > inside the component.
> >
> > Am I attacking this problem in the wrong way? Is this one of those
> > things that has an easy solution I'm not seeing? Or is this a genuine gap?
> >
> > --Lincoln
> >
> >
6:24 a.m.
In general, the EE programming model encourages you to separate your
domain model (entities) and persistence logic (the persistence
context) into separate objects. To have task.delete() you need to
create a DTO which adapts between these two layers. This can be
considered an issue as it is both unnecessary code, and can complicate
your domain model and business logic. Further, I think it's fair to
say that in general, EE 5+ has been about trying to reduce the amount
of boilerplate code required.
On 18 Aug 2009, at 00:38, Jim Driscoll wrote:
Maybe I'm dense. OK, probably I'm dense, but if you're
passing a
Task object into the composite component, why not have that object
also have the save and delete method on it? There's no need for a
method to have a parameter if it's already a part of the object it
acts on.
So, instead of delete(task), you'd have task.delete(). Isn't that
possible?
Then, you should be able to use those passed methods as your action
and valueChange targets right?
What am I missing?
Jim
P.S. Not that it wouldn't be handy to execute arbitrary methods on
the server - in one of my examples (poll, I think), I did resort to
a hidden button that I call click() on to do just that. Icky.
On 8/12/09 3:31 PM, Lincoln Baxter, III wrote:
> Ok, so perhaps I should explain my dataTable/ui:repeat use case a
> little
> bit more, since it seems like some of these options are not going
> very
> smoothly for me. I've labeled 3 questions, just to keep this long
> message slightly more organized.
>
> *The Scenario:*
> -----------------------------------------------------------------------
>
> Everything on your website is RequestScoped -- There are no stateful
> pages or SessionScoped beans whatsoever. That means that data is
> loaded
> every time a user accesses a page via GET, POST, etc... if an ajax
> event
> on a page updates some value - it actually needs to be updated via a
> service call on the back-end.
>
> You have an Object: "Task" -- a Task has an Assignee, a few Dates,
> and a
> Status.
>
> In order to keep the look and feel of Tasks consistent on the UI,
> you've
> created a "taskBlock.xhtml" composite component to handle the layout.
> However -- you would like inline editing and updating of the Task
> data
> to work via Ajax.
>
> Each taskBlock component instance needs to be able to save, delete
> its
> given Task object instance. Hence, you need:
>
> * a delete(Task) action to occur on a commandButton action event
> (this
> part is easy thanks to JBoss Seam/EL2)
> * a save(Task) method to be called on a ValueChangeEvent for each
> editable field
>
> The latter is the hard part, because the task object may have come
> from
> a list, it may have been passed in by itself. A workaround would be
> to
> have a "Save" button, but that's an extra click for the user, and
> ugly,
> etc, lots of reasons why you wouldn't want this.
> ValueChanceListeners do
> not accept properties, or allow user-specified ValueChange Methods
> to be
> supplied.
>
> *Solutions?*
> -----------------------------------------------------------------------
>
> I tried including a hidden commandLink in the Ajax execute=""
> attribute
> in order to trigger the action after the ValueChangeEvent, but it
> never
> fires -- not sure if that's a bug or intended.
>
> ***Question 1: *Almost every AJAX framework I know of allows you to
> simply execute a method on the server side, with or without params,
> and
> return a result... is this possible with JSF's Ajax framework?
>
> What would be optimal, would be if you could supply, as mentioned
> in a
> previous message in this chain, a ValueChangeMethod:
>
> <h:inputText>
> <f:valueChangeMethod method="saveTask(t)" />
> </h:inputText>
>
> or
>
> <f:valueChangeMethod method="saveTask(event, t)" />
>
> Which is even more powerful if you consider the new EL, or JBoss
> EL. If
> the method contains a "ValueChangeEvent event" in the method
> signature,
> it should be injected into the call.
>
> Thus, you would not have to write extra classes, or bind any
> objects, or
> retrieve any rows from a DataModel or DataTable.
>
> ***Question 2:* Without changing the Spec, how would you achieve this
> and ensure the user interaction is the same? The value needs to be
> saved
> via Ajax when they change it on the UI... without clicking a save
> button. If there is no way to support this type of functionality in
> the
> spec currently, then I propose we add it.
>
> ***Question 3:* Is this really an uncommon use case? Does everyone
> make
> a separate view/edit page for lists of items?
>
> The UI JavaScript, CSS, and HTML is not my strong point -- perhaps a
> component writer would invest more time with JSF's Ajax JavaScript in
> order to get the behavior right via custom JS, CS, and HTML..?
>
> I'm basically trying to figure out if I'm way off base here, and
> need a
> paradigm readjustment. It seems like nobody else is raising issues
> like
> this online, so it's possible that JSF doesn't need to change; I'd
> just
> like to know what everyone else is eating before I push for a
> change ;)
>
> --Lincoln
>
>
> On Fri, 2009-08-07 at 14:14 -0700, Alexander Smirnov wrote:
>> ui:repeat is a normal JSF component that supports binding but
>> <c:forEach> is compilation directive only that has no component
>> associated with tag.
>> The question just recalls me one forgotten problem: h:dataTable and
>> ui:repeat is complete different components that doing similar jobs.
>> While ui:repeat knows about UIDataTable and works well inside it,
>> DataTable itself has no clue what UIRepeat is iteration component,
>> therefore rendering a set of tables using ui:repeat is not possible.
>>
>>
>> On 08/03/2009 12:54 PM, Lincoln Baxter, III wrote:
>> > So here's one of those,"why is this different than that?"
>> questions:
>> >
>> > Unless I'm mistaken, ui:repeat is not a component and therefore
>> cannot
>> > be bound to a backing bean, but -- would it make sense to support
>> > something *like*<h:dataTable> in order to support determining
>> the
>> > selected row on action events and value change events? A
>> component that
>> > would privide a bindable DataModel / List<Object> row access
>> like
>> > <h:dataTable>?
>> >
>> > *My use case is this:*
>> >
>> > * Managed Bean contains a List of objects
>> > * Each object rendered to screen with input field
>> > * User submits the input field (with a command link or
>> button, etc)
>> > * ManagedBean needs to take action on the appropriate row
>> values
>> >
>> >
>> > I have a list of objects - I need to render them onto the
>> screen (not
>> > necessarily in an HTML table, maybe a<ul> would be nicer) but
>> I can't
>> > use<ui:repeat> because each row has a commandLink, and I need
>> to be
>> > able to determine which row the user clicked on in order to
>> take the
>> > appropriate action.
>> >
>> > EL2 helps with this, but... now what if I have a
>> ValueChangeEvent for an
>> > input field on each<li> row? Now I can no longer use EL2 to
>> pass the
>> > row into the ValueChangeListener, and I would have to use
>> something like
>> > <f:setPropertyActionListener> which is not only getting
>> increasingly
>> > complicated, but I'd also have to set an attribute /inside/the
>> VCL
>> > itself, or in a bean VCL knows about - then referencing it -
>> which is
>> > terribly ugly. Now try to fit all that into a composite
>> component and it
>> > gets really ugly to try attaching tons of VCLs or ALs or SPALs
>> to values
>> > inside the component.
>> >
>> > Am I attacking this problem in the wrong way? Is this one of
>> those
>> > things that has an easy solution I'm not seeing? Or is this a
>> genuine gap?
>> >
>> > --Lincoln
>> >
>> >
5499
days inactive
5514
days old
jsr-314-open-mirror@lists.jboss.org
10 comments
6 participants
participants (6)
-
Alexander Smirnov -
Dan Allen -
Jim Driscoll -
Lincoln Baxter, III -
Martin Marinschek -
Pete Muir