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Posted to users@tapestry.apache.org by "talk.small" <ta...@gmail.com> on 2007/05/22 03:24:52 UTC
Does the 'source' of @For in a form got evaluated during a rewind ?
<form jwcid="cartForm">
<table class="shoppingcart">
<tr>
<td></td>
<td></td>
</tr>
</table>
</form>
I thought upon a rewind, the source="ognl:itemList" will not be evaluated by
pulling data from server side database, becuase the itemlist has been stores
as hidden fields in the generated html form. It is the items in hidden
fields that will be restored to the list for rewinding the loop.
But when I debug the page, the result is quite on the contrary:
getItemList() is got called in a rewinding to restore the data from
database. So why bother to store the list of items to as the hidden fields,
since they seems no use for the submision?
BTW, I am using T4.0.2
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Re: Does the 'source' of @For in a form got evaluated during a
rewind ?
Posted by "talk.small" <ta...@gmail.com>.
Jessek, thanks for your reply!
I know there is 'convert' mechnism to save the network bandwidth,
my understanding is, even with 'convert' mechnism, the question is still
there:
That is, upon rewinding, the item list of the for loop is constructed from
server side
(e.g. by invoking getItemList() to retrieve data from backend database), or
from
the hidden fields biggybacked in the submission?
And my second question maybe like 'why it is designed to be so'?
Simon
Jessek wrote:
>
> The reason being is that most of the time storing an entire object
> (serializing / size / etc ) is a huge amount of overhead both in terms of
> bandwidth and server execution time.
>
> You'd be better off using the "convert" / "keyExpression" or "primaryKeys"
> parameter to the component - in which case only the very minimal needed to
> match a specific object is stored in the form.
>
> http://tapestry.apache.org/tapestry4.1/components/general/for.html
>
> On 5/21/07, talk.small <ta...@gmail.com> wrote:
>>
>>
>> <form jwcid="cartForm">
>> <table class="shoppingcart">
>>
>> <tr>
>> <td></td>
>> <td></td>
>> </tr>
>>
>> </table>
>> </form>
>>
>>
>> I thought upon a rewind, the source="ognl:itemList" will not be evaluated
>> by
>> pulling data from server side database, becuase the itemlist has been
>> stores
>> as hidden fields in the generated html form. It is the items in hidden
>> fields that will be restored to the list for rewinding the loop.
>>
>> But when I debug the page, the result is quite on the contrary:
>> getItemList() is got called in a rewinding to restore the data from
>> database. So why bother to store the list of items to as the hidden
>> fields,
>> since they seems no use for the submision?
>>
>> BTW, I am using T4.0.2
>>
>>
>>
>> --
>> View this message in context:
>> http://www.nabble.com/Does-the-%27source%27-of-%40For-in-a-form-got-evaluated-during-a-rewind---tf3793753.html#a10730070
>> Sent from the Tapestry - User mailing list archive at Nabble.com.
>>
>>
>> ---------------------------------------------------------------------
>> To unsubscribe, e-mail: users-unsubscribe@tapestry.apache.org
>> For additional commands, e-mail: users-help@tapestry.apache.org
>>
>>
>
>
> --
> Jesse Kuhnert
> Tapestry/Dojo team member/developer
>
> Open source based consulting work centered around
> dojo/tapestry/tacos/hivemind. http://blog.opencomponentry.com
>
>
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Re: Does the 'source' of @For in a form got evaluated during a rewind ?
Posted by Jesse Kuhnert <jk...@gmail.com>.
The reason being is that most of the time storing an entire object
(serializing / size / etc ) is a huge amount of overhead both in terms of
bandwidth and server execution time.
You'd be better off using the "convert" / "keyExpression" or "primaryKeys"
parameter to the component - in which case only the very minimal needed to
match a specific object is stored in the form.
http://tapestry.apache.org/tapestry4.1/components/general/for.html
On 5/21/07, talk.small <ta...@gmail.com> wrote:
>
>
> <form jwcid="cartForm">
> <table class="shoppingcart">
>
> <tr>
> <td></td>
> <td></td>
> </tr>
>
> </table>
> </form>
>
>
> I thought upon a rewind, the source="ognl:itemList" will not be evaluated
> by
> pulling data from server side database, becuase the itemlist has been
> stores
> as hidden fields in the generated html form. It is the items in hidden
> fields that will be restored to the list for rewinding the loop.
>
> But when I debug the page, the result is quite on the contrary:
> getItemList() is got called in a rewinding to restore the data from
> database. So why bother to store the list of items to as the hidden
> fields,
> since they seems no use for the submision?
>
> BTW, I am using T4.0.2
>
>
>
> --
> View this message in context:
> http://www.nabble.com/Does-the-%27source%27-of-%40For-in-a-form-got-evaluated-during-a-rewind---tf3793753.html#a10730070
> Sent from the Tapestry - User mailing list archive at Nabble.com.
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@tapestry.apache.org
> For additional commands, e-mail: users-help@tapestry.apache.org
>
>
--
Jesse Kuhnert
Tapestry/Dojo team member/developer
Open source based consulting work centered around
dojo/tapestry/tacos/hivemind. http://blog.opencomponentry.com