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Re: Validating form inputs?

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Davej wrote:
> Lew wrote:
>> Daniel Pitts wrote:
>>> Davej wrote:
>>>> I have been thinking about the way I have been validating form
>>>> inputs in the servelet [sic] and wonder if I would be much
>>>> better off using class methods to verify these inputs?
>>
>> What exactly do you mean by "class methods"? Do you mean 'static'
>> member methods?
>>
>>>> Consider that I am almost always gathering the inputs to
>>>> instantiate one or more objects, but I gather and validate
>>>> -- and then instantiate. Maybe I should instantiate an empty
>>>> object and then use class methods to validate the inputs?
>>
>> Maybe.  It depends on what you mean by "class methods".
>>
> 
> Why? I think it could be done either way. If it was a static method is
> would be made generic. If it was non-static it could be an alternate
> set method...

You asked if you "should instantiate an empty object". That would not be needed if using static methods only. That's why I said "it depends on what you mean by 'class methods'".

> public String ValidateAndSetQuiz1(String q1) //returns error message

Please follow the Java naming conventions.

> {
>   double score;

You could narrow the scope of 'score' more if you wanted to.

>   try{
>      score = Double.parseDouble(q1);
>      if ( score < 0 || score > 100.0)
>         return "Value out of allowed range";
> 
>   }catch (Exception e)

What exception are you catching?

For most routines, catching just 'Exception' is an antipattern.

>   {
>      return "Value is non-numeric";

And as Daniel noted, this is not often the best way to handle an exception.

I would wonder if logging the exception is appropriate here, perhaps.

>   }
> 
>   m_quiz1 = score; //accept and set instance variable m_quiz1
>   return null; //signifies that submitted value was accepted
> }

It's more conventional to return a value than 'null' or a 'String' that are not in the value domain.

It's likely to be better engineering to separate setting and validation into different methods.

-- 
Lew

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Thread

Validating form inputs? Davej <galt_57@hotmail.com> - 2012-03-20 11:16 -0700
  Re: Validating form inputs? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-03-20 12:08 -0700
    Re: Validating form inputs? Lew <lewbloch@gmail.com> - 2012-03-20 12:50 -0700
      Re: Validating form inputs? markspace <-@.> - 2012-03-21 09:24 -0700
      Re: Validating form inputs? Davej <galt_57@hotmail.com> - 2012-03-21 12:02 -0700
        Re: Validating form inputs? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-03-21 12:59 -0700
        Re: Validating form inputs? Lew <lewbloch@gmail.com> - 2012-03-21 13:37 -0700
    Re: Validating form inputs? Davej <galt_57@hotmail.com> - 2012-03-20 12:56 -0700
      Re: Validating form inputs? Lew <lewbloch@gmail.com> - 2012-03-20 13:58 -0700
      Re: Validating form inputs? markspace <-@.> - 2012-03-21 09:30 -0700
  Re: Validating form inputs? Roedy Green <see_website@mindprod.com.invalid> - 2012-03-20 14:28 -0700
    Re: Validating form inputs? Gene Wirchenko <genew@ocis.net> - 2012-03-20 19:16 -0700
      Re: Validating form inputs? Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-03-21 17:41 -0300
        Re: Validating form inputs? Gene Wirchenko <genew@ocis.net> - 2012-03-21 14:46 -0700
          Re: Validating form inputs? Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2012-03-21 19:54 -0300
        Re: Validating form inputs? Roedy Green <see_website@mindprod.com.invalid> - 2012-03-22 10:34 -0700
      Re: Validating form inputs? Lew <lewbloch@gmail.com> - 2012-03-21 14:56 -0700
        Re: Validating form inputs? Gene Wirchenko <genew@ocis.net> - 2012-03-21 19:09 -0700
          Re: Validating form inputs? Daniel Pitts <newsgroup.nospam@virtualinfinity.net> - 2012-03-22 08:36 -0700
            Re: Validating form inputs? Gene Wirchenko <genew@ocis.net> - 2012-03-22 09:40 -0700

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