Re: Value-ChangeEvent under Struts-Faces
Dear Craig,
Thanks a lot, but I'm still a bit confused...
Is mybean an ActionForm, an Action or an adapter to Faces Backing Bean ???
Gracias!!
This kind of thing will work in Struts-Faces, but only if you correctly
specify the expressions, and use an input field :-)
h:inputText id=city value=#{mybean.city} valueChangeListener=#{
mybean.cityChanged}/
Craig
---
Re: Value-ChangeEvent under Struts-Faces
On 2/20/06, Leila Carvalho [EMAIL PROTECTED] wrote:
Dear Craig,
Thanks a lot, but I'm still a bit confused...
Is mybean an ActionForm, an Action or an adapter to Faces Backing Bean ???
Gracias!!
Technically, mybean would be a Faces backing bean, but it *could* be any
of the above ... JSF does not care whether or not backing beans implement a
particular interface, or subclass a particular base class. But you have to
be careful of one particular scenario. Struts only creates one instance of
an Action class for the entire application, so that is not a good place to
put request-specific event handlers.
By the way, are you writing a new application, or trying to adapt something
that already exists? If it is a new work, you'll find it a *lot* simpler to
just go with JSF, or use JSF+Shale, rather than trying to use the
integration library. The library fits best when you are trying to
incrementally add JSF based facilities to an existing Struts based webapp.
Craig
This kind of thing will work in Struts-Faces, but only if you correctly
specify the expressions, and use an input field :-)
h:inputText id=city value=#{mybean.city} valueChangeListener=#{
mybean.cityChanged}/
Craig
---
Re: Value-ChangeEvent under Struts-Faces
Craig, First of all, congratulations for your Struts-Faces library!! This library is what I have been looking for.. be careful of one particular scenario. Struts only creates one instance of an Action class for the entire application, so that is not a good place to put request-specific event handlers. --great!!! I´m newbie in Faces, so I´m dissecting struts-faces' very good examples 1 and 2. I´m sure that all run well for actionEvents and there are some backing beans for that. Please, is there some sample code for Value-change Events in Struts-Faces??? I would like saving time not doing my own tests... By the way, are you writing a new application, or trying to adapt something that already exists? --My Struts application already exists. All I need at first is avoiding JavaScript when relating 2 modal comboboxes. Can I apply Value-change Events instead?? Thanks!! --
Re: Value-ChangeEvent under Struts-Faces
On 2/20/06, Leila Carvalho [EMAIL PROTECTED] wrote:
Craig,
First of all, congratulations for your Struts-Faces library!!
This library is what I have been looking for..
be careful of one particular scenario. Struts only creates one instance
of
an Action class for the entire application, so that is not a good place
to
put request-specific event handlers.
--great!!!
I´m newbie in Faces, so I´m dissecting struts-faces' very good examples 1
and 2.
I´m sure that all run well for actionEvents and there are some backing
beans
for that.
Please, is there some sample code for Value-change Events in
Struts-Faces???
I would like saving time not doing my own tests...
By the way, are you writing a new application, or trying to adapt
something
that already exists?
--My Struts application already exists. All I need at first is avoiding
JavaScript when
relating 2 modal comboboxes. Can I apply Value-change Events instead??
Here is an outline of one way to accomplish this task -- it's not by any
means the only possible pattern.
I need to start with an assumption -- that the relationship between the two
combo boxes is specific to a particular user? If so, that means the backing
bean we are talking about will naturally fit into session scope. Next, I'll
make one more assumption ... the set of options in the second checkbox
should depend on the user's choice in the first box. If I'm correct so far,
let's pretend the first combobox is the set of US states, and the second one
changes to be the set of cities appropriate to that state. This is just to
make the illustration clearer.
Now, assume you have a backing bean called geography that is defined to be
a managed bean in session scope. On this bean, you'll have two methods:
// Return selection items for *all* states
public SelectItem[] getStates() { return this.states; }
// Return selection items for cities in the specified state
public SelectItem[] getCities() { return this.cities; }
With a couple of instance variables (by the way, SelectItem is the
representation of the label and value of a particular option to show in a
dropdown).
// Initialize the states list to all the state abbreviations and names
private SelectItem[] states = new SelectItem[] {
new SelectItem(AL, Alabama),
new SelectItem(AK, Alaska),
...
}
// Initialize the cities list to a zero-length arary
private SelectItem[] cities = new SelectItem[0];
In addition, this bean might have a value change listener method like this:
// Respond to changes in which state is selected
public void stateChanged(ValueChangeEvent event) {
String newState = (String) event.getNewValue();
cities = ... calculate array of cities based on the value of
newState ...
}
Putting this together into one page, you would have your two combo boxes
declared something like this:
h:selectOneMenu id=state value=#{formBean.state}
valueChangeListener=#{geography.stateChanged}
f:selectItems value=#{geography.states}/
/h:selectOneMenu
h:selectOneMenu id=city value=#{formBean.city}
f:selectItems value=#{geography.cities}/
/h:selectOneMenu
There are a couple of issues still to deal with your comment about doing
this kind of thing without Javascript but the details really depend on how
seriously that is actually to be taken. Making this work with Javascript
disabled in the browser, for example, is possible ... but you have to be
ready to deal with the fact that you need the entire form submitted for the
value change event to be fired, since it (like all the other events that JSF
defines) happen on the *server*, not on the *client*.
It's also possible to look for combo box components that are more
sophisticated than the one defined by the standard ... perhaps even one that
uses AJAX techniques to change the city list on the fly, without requiring a
form submit. But any component like this is going to depend on being able
to execute Javascript in the client.
Thanks!!
--
Craig
Re: Value-ChangeEvent under Struts-Faces
From: Leila Carvalho [EMAIL PROTECTED]
Can I apply Value-change Event in my jsp pages under Struts-Faces
Integration ???
How??
Thanks in advance.
Leila.
You can add a value change listener as an action binding method on a backing
bean,
h:outputText id=city value=mybean.city
valueChangeListener=mybean.cityChanged/
public void cityChanged(ValueChangeEvent event) {
}
or, as a nested object.
h:ouputText id=city value=mybean.city
f:valueChangeListener type=com.acme.MyListener/
/h:ouputText
public class MyListener implements ValueChangeListener {
public void processValueChange(ValueChangeEvent event) {
}
}
Gary
Re: Value-ChangeEvent under Struts-Faces
On 2/19/06, Gary VanMatre [EMAIL PROTECTED] wrote:
From: Leila Carvalho [EMAIL PROTECTED]
Can I apply Value-change Event in my jsp pages under Struts-Faces
Integration ???
How??
Thanks in advance.
Leila.
You can add a value change listener as an action binding method on a
backing bean,
h:outputText id=city value=mybean.city valueChangeListener=
mybean.cityChanged/
This kind of thing will work in Struts-Faces, but only if you correctly
specify the expressions, and use an input field :-)
h:inputText id=city value=#{mybean.city} valueChangeListener=#{
mybean.cityChanged}/
Craig
public void cityChanged(ValueChangeEvent event) {
}
or, as a nested object.
h:ouputText id=city value=mybean.city
f:valueChangeListener type=com.acme.MyListener/
/h:ouputText
public class MyListener implements ValueChangeListener {
public void processValueChange(ValueChangeEvent event) {
}
}
Gary
