Had another look at the form wizard.
Studying the code in more detail helped me understand what can be
abstracted out of routine multi-page forms processing. It was a good
exercise.
For those interested, looks like the cake wizard would save the
following code every step of the way:
1. Navigation
--------------------
- your code doesn't have to check if the next or previous buttons were
pressed, the wizard does this based on the name of the link
("previous" or "next").
- your code doesn't have to figure out which action to call, as that
is configured up front in "ways", when you init the wizard.
- if you didn't have the wizard, each of your form actions would have
to determine if the "Next" or "Previous" link was pressed, then
redirect itself to the proper action.
- Also, if you have multiple ways through your steps, the wizard
handles those transparently to you, so you don't have to check at each
step where to go next. For example, if the user is not registered, the
wizard will know to first take him to the registration page, then to
the login page to login, then back to the page which required login in
the first place. (of course, in your validation routines you would
have to change the "way" if you see the user is not logged in, I
think).
2. Checking for the presence of data
-----------------------------------------------------
- the wizard checks to see if there is form data submitted, and if
not, calls the current action to redisplay the form with the error
messages as appropriate.
- if you didn't have the wizard, you would have to perform this check.
Not much, but is one less thing to do.
3. Validation
-------------------
- the wizard calls the appropriate validation routines you supply each
step of the way, and reinvokes the same action (which causes the
associated view to be displayed) if there are errors.
- if there are no errors, it invokes the action for the next step,
according to the "ways" you defined at init time.
- If you didn't have the wizard, you would have to call validate
yourself (if you had multiple models involved, or custom validation).
Again, not much, but something else your code doesn't have to do.
4. Accumulating and storing/ retrieving form data in Sessions
-----------------------------------------------------------------------------------------
- after each step, the wizard takes care of storing and accumulating
all the form field data in cake sessions, so you don't have to.
- after reading and writing all the form variables to the session, the
wizard updates everything into the regular cake format $this-
>data['model']['field'] style (even though it is managing it
underneath in sessions) so you can process it like usual cake
programming (ie. both Save validate will find the data).
- by using sessions, it eliminates for you some of the data
accumulation problems of BACK and FORWARD through the steps, and deals
with the session variables transparently to you. Your code doesn't
need to be concerned with sessions at all.
- if you didn't have the wizard, you would have to manage the form
data yourself in sessions, and update the $this->data['model']
['field'] yourself from the sessions before saving.
5. Clearing the session data at the end
---------------------------------------------------------
- after the last step, the wizard clears the session data.
- if you didn't have the wizard, you would have to do this yourself.
NOTE: all the above is only from reading the code. I have not played
with it yet, so please take all the above with a grain of salt, and
verify everything for yourself.
Question
-------------
One of the things I was not sure about - perhaps someone can clarify -
the way the wizard invokes your action is:
$this->controller->$fct(); // $fct() is the name of your action
Does this mean you must put all the actions for that multi-page form
into a single controller?
What do you do if it makes more sense to have different steps of the
form processed by different controllers?
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