What do you think of Arron's idea, Craig? It would be ten times more intuitive to
have DynaForms work more like an ArrayList - you instantiate the form, call an indexed
setter and it just works - no exceptions. Rick and I are merely the first of many who
will hit this annoying, counter-intuitive, undocumented speed bump. Rick finally gave
up and just went back to regular ActionForms, and I came close to that before I
figured it out.
I haven't looked into the lazy collections code yet, but it sounds like a great
solution.
Roman
-----Original Message-----
From: Arron Bates [mailto:[EMAIL PROTECTED]]
Sent: Wed 7/17/2002 5:28 AM
To: Struts Users Mailing List
Cc:
Subject: Re: Re[2]: getting nested tags to work with DynaActionForm???
Craig, wouldn't this be fixed by getting the collections in the
DynaForm
to be wrapped by the lazy lists I commited a few weeks ago to
commons?... then when they're being created when the request comes in,
it'll all grow as needed and it'd just happen.
Been missing the past couple of weeks due to bad flu among other
things.
Love to get in there and code it, but time is hard to find at the
moment
and there's other things I need to get on to, but the above feels like
a
good marriage.
One of the things I have to do is describe the lazy collections to the
masses. Seems a few have had list constrcution issues with request
scope
beens in the last fortnight.
On Wed, 2002-07-17 at 12:45, Craig R. McClanahan wrote:
>
>
> On Tue, 16 Jul 2002, Rick Reumann wrote:
>
> > Date: Tue, 16 Jul 2002 22:04:54 -0400
> > From: Rick Reumann <[EMAIL PROTECTED]>
> > To: Craig R. McClanahan <[EMAIL PROTECTED]>
> > Cc: Struts Users Mailing List <[EMAIL PROTECTED]>
> > Subject: Re[2]: getting nested tags to work with DynaActionForm???
> >
> > On Tuesday, July 16, 2002, 9:04:04 PM, Craig R. McClanahan wrote:
> >
> > CRM> Setting stuff like this up in the reset() method is the
standard approach.
> > CRM> Arrays have to exist already for either standard
JavaBean-based
> > CRM> ActionForms, as well as DynaActionForms.
> >
> > I'm still a bit confused by this. When I use a standard
> > ActionForm I don't have to do anything special with my
ArrayList
> > in the ActionForm. A page that uses this ArrayList works
fine.
> > However as soon as I try to use this ArrayList as property in
a
> > DynaActionForm I run into problems trying to submit a jsp
page
> > that was populated with the ArrayList info (the display works
> > fine, it's just upon submission).
> >
>
> If you're using request scope beans, a new instance gets created on
every
> request. And I will bet that you probably have an initialization of
this
> array happening in your constructor, or in an initialization
expression,
> right?
>
> For DynaActionForm instances, the default initialization of all
> non-primitives in null. That's why you still need to initialize in
> reset(), or use the new "initial" property described below.
>
> > CRM> In recent nightly builds, we added support for an additional
mechanism --
> > CRM> you can declare an intiialization expression for arrays in
the
> > CRM> <form-property> for a DynaActionForm bean, using the
"initial" attribute.
> > CRM> The syntax is basically like what you use in Java to
initialize an array
> > CRM> to a set of values in a variable declaration -- for example:
> >
> > CRM> <form-bean name="myform"
> > CRM> type="org.apache.struts.action.DynaActionForm">
> >
> > CRM> <form-property name="intArray" type="int[]"
> > CRM> initial="{ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 }"/>
> >
> > CRM> </form-bean>
> >
> > What if the information in an ArrayList of beans that you
want in a
> > DynaActionForm is to first be populated by some database
info.
> > Do you need to first initialize it like a above to a bunch
of
> > nulls? If so what if the list size fluctuates (hence use of
> > ArrayList) how do you know how many to initialize the
ArrayList
> > with?
> >
>
> That's definitely a place where loading the arrays in the reset()
method
> makes sense.
>
> Having an "intArray" property of type "int[]" on a DynaBean is very
much
> like having the following method signatures on a standard JavaBean:
>
> public int[] getIntArray();
> public void setIntArray(int intArray[]);
>
> so you don't have to pre-initialze the array to nulls or anything.
Just
> set up the array you want as a local variable (of any desired
> length), populate its values, and call:
>
> int intArray[] = ...;
> dynaform.set("intArray", intArray);
>
> One really common scenario is that you don't know ahead of time how
many
> items you're going to read from the database. An approach I use a
lot is
> to use an ArrayList to accumulate the values, then convert them to
an
> array. Something like this (assuming you have a "labels" property
of
> type "java.lang.String[]"):
>
> ArrayList temp = new ArrayList();
> Connection conn = ...;
> Statement stmt = conn.createStatement();
> ResultSet rs = stmt.executeQuery("select label from
customer_types");
> while (rs.next()) {
> temp.add(rs.getString(1));
> }
> String labels[] = (String[]) temp.toArray(new
String[temp.size()]);
> dynaFormBean.set("labels", labels);
>
> Alternatively, you could set your property type to java.util.List
instead
> -- all the Struts tags that support indexed access against arrays
work
> perfectly well against a List as well.
>
> > Thanks for any more thoughts.
> >
> > --
> >
> > Rick
> >
> > mailto:[EMAIL PROTECTED]
> >
> >
>
> Craig
>
>
>
> --
> To unsubscribe, e-mail:
<mailto:[EMAIL PROTECTED]>
> For additional commands, e-mail:
<mailto:[EMAIL PROTECTED]>
