empty fields of an input form get default value after submitting

[Sandra Reichert <re...@bni-hamburg.de>]

Hi,

I have an input form in jsp. After submitting empty fields (user entered
nothing in input field) are set by default with specific values
depending on their data typ.
So an empty Integer field is set to 0, an String field to "" an so on.

But i want to have a null value for empty fields.
Or in other words: How can i decide if for example the 0 is entered by
user or the default initialization.

Can anybody help ....


Thanks
Sandra Reichert



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Re: empty fields of an input form get default value after submitting

[Scott Van Wart <sc...@indosoft.com>]

Laurie Harper wrote:
> Sandra Reichert wrote:
>> Hi,
>>
>> I have an input form in jsp. After submitting empty fields (user entered
>> nothing in input field) are set by default with specific values
>> depending on their data typ.
>> So an empty Integer field is set to 0, an String field to "" an so on.
>>
>> But i want to have a null value for empty fields.
>> Or in other words: How can i decide if for example the 0 is entered by
>> user or the default initialization.
>
> This is one of the many reasons you should prefer String-valued form 
> bean properties, rather than using int/Integer, etc. That way, you can 
> redisplay incorrect/invalid inputs for the user to edit and correct. 
> What if the user types 'two' into a field that's backed by an 
> Integer-typed property? Resetting it to 0 is clearly not what you 
> want, but resetting it to null isn't great either.
>
> If you don't care about redisplaying input values and/or you really 
> can't change your form properties to be String-typed, the best you can 
> do it to re-configure the BeanUtils converters to use null as a 
> default instead of 0.

I use Long/Integer for hidden, state fields that the user won't 
see/can't change.  I've been thinking of using them for <option...> 
values as well, since the user can't see those either.  Idea being that 
the only way the user can change these values is by editing the HTML 
source.  If they do that, all bets are off :).  As long as it doesn't 
muck up the application.  Though I should probably point out the people 
who are using my web apps are the same people who requested it, and no 
more.  Things would obviously be a little different on a public web site 
if a user managed to edit someone else's profile by changing something 
like <input type="hidden" name="userId" value="4"> to another number on 
the system :).

- Scott

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Re: empty fields of an input form get default value after submitting

[Laurie Harper <la...@holoweb.net>]

Sandra Reichert wrote:
> Hi,
> 
> I have an input form in jsp. After submitting empty fields (user entered
> nothing in input field) are set by default with specific values
> depending on their data typ.
> So an empty Integer field is set to 0, an String field to "" an so on.
> 
> But i want to have a null value for empty fields.
> Or in other words: How can i decide if for example the 0 is entered by
> user or the default initialization.

This is one of the many reasons you should prefer String-valued form 
bean properties, rather than using int/Integer, etc. That way, you can 
redisplay incorrect/invalid inputs for the user to edit and correct. 
What if the user types 'two' into a field that's backed by an 
Integer-typed property? Resetting it to 0 is clearly not what you want, 
but resetting it to null isn't great either.

If you don't care about redisplaying input values and/or you really 
can't change your form properties to be String-typed, the best you can 
do it to re-configure the BeanUtils converters to use null as a default 
instead of 0.

L.


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