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From Laurie Harper <>
Subject Re: Dynamically Initializing Checkbox Value
Date Wed, 30 Aug 2006 17:34:08 GMT
Yes you do, the form is passed in as one of the parameters to execute(). 
The typical pattern is for the action to be invoked via an action 
mapping, populate the form bean and forward to the JSP. It's during this 
action processing that you copy your business data into the form bean, 
thus initializing it.

The form in the JSP is then bound to the form bean, both reading from 
and writing to the same place. When the form is submitted, another 
action is invoked and in that action you copy the appropriate data from 
the form to wherever you need it to complete the operation.

To answer your earlier question, you *can* have a form which takes its 
values from a bean other than the form bean -- I think you've already 
had that working for some input types. However, in the case of 
checkboxes, that's going to be problematic, since the input's value is 
doing double duty -- it's specifying the value that should be submitted 
*if* the checkbox is selected, and also specifying the value that the 
checkbox property must have for it to be considered selected already.

If you don't want to copy the permission data from your model into the 
form bean before rendering the form, you can do as previously suggested 
and put the entire business object into the form bean; that solution 
actually doesn't prevent the properties being written/updated. There are 
problems with this approach for certain types of inputs, but for boolean 
values rendered as checkboxes it should work fine.


Anthony N. Frasso wrote:
> I guess I don't follow....
> How do I prepopulate the form bean?  I have a list
> page which lists all of the roles in the system.  When
> the form on the list page is submitted, I can retrieve
> the ID of the role that the user wants to edit.  In
> the action class I then retrieve that role, and put it
> into the request scope.
> The question is... how do I pre-populate the form bean
> with that role?  I don't have access to the form bean
> yet from the action class.
> Regards,
> Anthony Frasso
> --- Puneet Lakhina <> wrote:
>> On 8/30/06, Anthony N. Frasso <>
>> wrote:
>>> Actually, that's incorrect.  I want to *read* from
>> the
>>> Role bean.  I want to *write* to the form bean.  I
>>> just don't know how to go about it yet. :)  It
>> seems
>>> like I have to read/write to the same form bean,
>> which
>>> doesn't make sense, because I don't have the form
>> bean
>>> until I get to the JSP page, so there's no way to
>>> initialize it.
>> Actually you have probably missed the total concept
>> of prepopulating. You
>> put initial values in you form beans, when your JSP
>> page loads your struts
>> tags call the getter methods of the relevant  to put
>> initial values in your
>> fields. And then when the form is submitted setter
>> methods are called
>> followed by validate(if present and the action has
>> set validate="true"), and
>> in case of no errors in validate the action methods
>> execute is called which
>> in turn returns a forward to a page.
>> so your cycle for a normal form submit is like this.
>> request for jsp->prepoulate using getter->jsp
>> rendered->submit->call
>> setters->validate->if no errors ->execute of
>> Action->forward
>> -- 
>> Puneet
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