Wizard pages in Struts design question
I read the HowTo write a wizard on the Struts web-site but I wasn't
really happy with the solution, and I am looking for a better one. I
came up with another way and I would appreciate your comments.
The design consists of:
- The 'form' is a session scope form
- WizardAction class (a DispatchAction based) with following methods:
* init () - starting the wizard and redirect to the first page
* finish () - (or save()) finish the wizard and save the
information in the form using some business logic
delegate.
- Each Page or step in the wizard is a separate Action class, extending
a WizrardBaseAction (a DispatchAction based) which contains some
shared methods.
For example: Page1Action extends WizardBaseAction {
// initializes the page (done only on first
encounter)
ActionForward init (mapping,...) throws
Exception;
ActionForward back (mapping,...) throws
Exception;
ActionForward next (mapping,...) throws
Exception; ActionForward finish
(mapping,...) throws Exception;
}
- Each page/step has a separate action-mapping item in the configuration
with local forwards for : 'back' (if not the first page), 'next',
'finish' (if allowed from that page).
I apologize for not sketching the whole idea down to the last bit but I
hope you get the picture.
Only problem is that this design touches the question of chaining
actions verses forward redirection (not just dispatching).
For example the Page1Action.next() does the following:
1. validate the page
2. perform whatever processing required
3. return the next action to forward to (redirect or chain with
all its illness..)
In my opinion (humble one of course :) having such a separation keeping
each step in its own class is better and clearer design than having them
all in the same Action class.
Isn't there a way to prevent the reset + pre-population of the form done
while chaining actions? Furthermore, is it so bad to redirect between
actions?
Thanks in advance,
Erez
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Re: Wizard pages in Struts design question
To prevent repopulation of an ActionForm's properties, you just need to
provide a property that observes that status of another property that
indicates whether the form is readonly or not. So, instead of just doing
this.property = property
you have
if (mutable) this.property = property
Or do something more sophisticated, like have it look at the page number
and then decide whether to set itself or not.
Though, IMHO, the behavior for a step is so complicated that you want to
put it in its own action, it should probably be outside of Struts all
together, and part of the business logic layer.
(This is why chaining is frowned upon. It's a red flag that indicates
business logic is creeping into your Action classes. When the business
logic is sufficiently fine-grained, you should just be able to whatever
you need to do from whatever Action you happen to be in. As work
progresses on Commons Chain, I think this will provide a solution many
people will prefer to chaining Struts Action).
I haven't had a chance to abstract it into a standard class, but here's
a wizard Action that I'm working with now. It submits back to the same
class, but uses a dispatch action so that if a step needs more behavior
it can be encapsulated that way.
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/wqdata/wqdata/src/java/apps/cpu/us_ok_deq_wqdata/cpu/WizardAction.java
The steps are laid out as ActionForwards to the instant ActionMapping,
making it very easy to rewrite.
-Ted.
Erez Efrati wrote:
I read the HowTo write a wizard on the Struts web-site but I wasn't
really happy with the solution, and I am looking for a better one. I
came up with another way and I would appreciate your comments.
The design consists of:
- The 'form' is a session scope form
- WizardAction class (a DispatchAction based) with following methods:
* init () - starting the wizard and redirect to the first page
* finish () - (or save()) finish the wizard and save the
information in the form using some business logic
delegate.
- Each Page or step in the wizard is a separate Action class, extending
a WizrardBaseAction (a DispatchAction based) which contains some
shared methods.
For example: Page1Action extends WizardBaseAction {
// initializes the page (done only on first
encounter)
ActionForward init (mapping,...) throws
Exception;
ActionForward back (mapping,...) throws
Exception;
ActionForward next (mapping,...) throws
Exception; ActionForward finish
(mapping,...) throws Exception;
}
- Each page/step has a separate action-mapping item in the configuration
with local forwards for : 'back' (if not the first page), 'next',
'finish' (if allowed from that page).
I apologize for not sketching the whole idea down to the last bit but I
hope you get the picture.
Only problem is that this design touches the question of chaining
actions verses forward redirection (not just dispatching).
For example the Page1Action.next() does the following:
1. validate the page
2. perform whatever processing required
3. return the next action to forward to (redirect or chain with
all its illness..)
In my opinion (humble one of course :) having such a separation keeping
each step in its own class is better and clearer design than having them
all in the same Action class.
Isn't there a way to prevent the reset + pre-population of the form done
while chaining actions? Furthermore, is it so bad to redirect between
actions?
Thanks in advance,
Erez
-
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For additional commands, e-mail: [EMAIL PROTECTED]
--
Ted Husted,
Junit in Action - http://www.manning.com/massol/,
Struts in Action - http://husted.com/struts/book.html,
JSP Site Design - http://www.amazon.com/exec/obidos/ISBN=1861005512.
Get Ready, We're Moving Out!! - http://www.clark04.com
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RE: Wizard pages in Struts design question
Ted,
From reading your WizardAction code it seems that in a way it maintains
an internal mechanism of redirection between the submitting of the
current step and preparation of the next step sub-actions, while keeping
Struts out of it. So in the end - not exposing the internal redirection
avoids the famous Struts action chaining issue.
Erez
-Original Message-
From: Ted Husted [mailto:[EMAIL PROTECTED]
Sent: Sunday, September 21, 2003 5:00 PM
To: Struts Users Mailing List
Subject: Re: Wizard pages in Struts design question
To prevent repopulation of an ActionForm's properties, you just need to
provide a property that observes that status of another property that
indicates whether the form is readonly or not. So, instead of just doing
this.property = property
you have
if (mutable) this.property = property
Or do something more sophisticated, like have it look at the page number
and then decide whether to set itself or not.
Though, IMHO, the behavior for a step is so complicated that you want to
put it in its own action, it should probably be outside of Struts all
together, and part of the business logic layer.
(This is why chaining is frowned upon. It's a red flag that indicates
business logic is creeping into your Action classes. When the business
logic is sufficiently fine-grained, you should just be able to whatever
you need to do from whatever Action you happen to be in. As work
progresses on Commons Chain, I think this will provide a solution many
people will prefer to chaining Struts Action).
I haven't had a chance to abstract it into a standard class, but here's
a wizard Action that I'm working with now. It submits back to the same
class, but uses a dispatch action so that if a step needs more behavior
it can be encapsulated that way.
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/wqdata/wqdata/src/java/ap
ps/cpu/us_ok_deq_wqdata/cpu/WizardAction.java
The steps are laid out as ActionForwards to the instant ActionMapping,
making it very easy to rewrite.
-Ted.
Erez Efrati wrote:
I read the HowTo write a wizard on the Struts web-site but I wasn't
really happy with the solution, and I am looking for a better one. I
came up with another way and I would appreciate your comments.
The design consists of:
- The 'form' is a session scope form
- WizardAction class (a DispatchAction based) with following methods:
* init () - starting the wizard and redirect to the first page
* finish () - (or save()) finish the wizard and save the
information in the form using some business logic
delegate.
- Each Page or step in the wizard is a separate Action class,
extending
a WizrardBaseAction (a DispatchAction based) which contains some
sharedmethods.
For example: Page1Action extends WizardBaseAction {
// initializes the page (done only on first
encounter)
ActionForward init (mapping,...) throws
Exception;
ActionForward back (mapping,...) throws
Exception;
ActionForward next (mapping,...) throws
Exception;ActionForward finish
(mapping,...) throws Exception;
}
- Each page/step has a separate action-mapping item in the
configuration
with local forwards for : 'back' (if not the first page), 'next',
'finish' (if allowed from that page).
I apologize for not sketching the whole idea down to the last bit but
I
hope you get the picture.
Only problem is that this design touches the question of chaining
actions verses forward redirection (not just dispatching).
For example the Page1Action.next() does the following:
1. validate the page
2. perform whatever processing required
3. return the next action to forward to (redirect or chain with
all its illness..)
In my opinion (humble one of course :) having such a separation
keeping
each step in its own class is better and clearer design than having
them
all in the same Action class.
Isn't there a way to prevent the reset + pre-population of the form
done
while chaining actions? Furthermore, is it so bad to redirect between
actions?
Thanks in advance,
Erez
-
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
--
Ted Husted,
Junit in Action - http://www.manning.com/massol/,
Struts in Action - http://husted.com/struts/book.html,
JSP Site Design -
http://www.amazon.com/exec/obidos/ISBN=1861005512.
Get Ready, We're Moving Out!! - http://www.clark04.com
-
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
-
To unsubscribe, e-mail: [EMAIL PROTECTED
RE: Wizard pages in Struts design question
About your suggestion of avoiding repopulating... I guess this cannot be
done using DynaActionForms, or am missing something?
I agree that the step code should be part of the logic but still the
action should activate it somehow, by calling it.
I can't see how chaining actions has to be an indication of logic code
creeping into the action code - It see how it can indicate but IMMO it's
not always the case. In the wizard example, I can't see why not having
each step in its own Struts action. Clicking next on the page1,
activates the submit on that step action, which may call some business
logic delegate to perform whatever is necessary, and then directing to
the next step dispatching its init method. After page2 step init()
method is done, it directs to something like 'viewForm' and next step is
displayed populated as required.
Erez
-Original Message-
From: Ted Husted [mailto:[EMAIL PROTECTED]
Sent: Sunday, September 21, 2003 5:00 PM
To: Struts Users Mailing List
Subject: Re: Wizard pages in Struts design question
To prevent repopulation of an ActionForm's properties, you just need to
provide a property that observes that status of another property that
indicates whether the form is readonly or not. So, instead of just doing
this.property = property
you have
if (mutable) this.property = property
Or do something more sophisticated, like have it look at the page number
and then decide whether to set itself or not.
Though, IMHO, the behavior for a step is so complicated that you want to
put it in its own action, it should probably be outside of Struts all
together, and part of the business logic layer.
(This is why chaining is frowned upon. It's a red flag that indicates
business logic is creeping into your Action classes. When the business
logic is sufficiently fine-grained, you should just be able to whatever
you need to do from whatever Action you happen to be in. As work
progresses on Commons Chain, I think this will provide a solution many
people will prefer to chaining Struts Action).
I haven't had a chance to abstract it into a standard class, but here's
a wizard Action that I'm working with now. It submits back to the same
class, but uses a dispatch action so that if a step needs more behavior
it can be encapsulated that way.
http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/wqdata/wqdata/src/java/ap
ps/cpu/us_ok_deq_wqdata/cpu/WizardAction.java
The steps are laid out as ActionForwards to the instant ActionMapping,
making it very easy to rewrite.
-Ted.
Erez Efrati wrote:
I read the HowTo write a wizard on the Struts web-site but I wasn't
really happy with the solution, and I am looking for a better one. I
came up with another way and I would appreciate your comments.
The design consists of:
- The 'form' is a session scope form
- WizardAction class (a DispatchAction based) with following methods:
* init () - starting the wizard and redirect to the first page
* finish () - (or save()) finish the wizard and save the
information in the form using some business logic
delegate.
- Each Page or step in the wizard is a separate Action class,
extending
a WizrardBaseAction (a DispatchAction based) which contains some
sharedmethods.
For example: Page1Action extends WizardBaseAction {
// initializes the page (done only on first
encounter)
ActionForward init (mapping,...) throws
Exception;
ActionForward back (mapping,...) throws
Exception;
ActionForward next (mapping,...) throws
Exception;ActionForward finish
(mapping,...) throws Exception;
}
- Each page/step has a separate action-mapping item in the
configuration
with local forwards for : 'back' (if not the first page), 'next',
'finish' (if allowed from that page).
I apologize for not sketching the whole idea down to the last bit but
I
hope you get the picture.
Only problem is that this design touches the question of chaining
actions verses forward redirection (not just dispatching).
For example the Page1Action.next() does the following:
1. validate the page
2. perform whatever processing required
3. return the next action to forward to (redirect or chain with
all its illness..)
In my opinion (humble one of course :) having such a separation
keeping
each step in its own class is better and clearer design than having
them
all in the same Action class.
Isn't there a way to prevent the reset + pre-population of the form
done
while chaining actions? Furthermore, is it so bad to redirect between
actions?
Thanks in advance,
Erez
-
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
--
Ted Husted,
Junit in Action
