# Javascript validation for a form?

**URL:** <https://www.ruby-forum.com/t/javascript-validation-for-a-form/137949>\
**Category:** Rails\
**Created:** [May 18, 2008, 8:58pm UTC](https://www.ruby-forum.com/t/javascript-validation-for-a-form/137949 "2008-05-18T20:58:01Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![san1981](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ad7895/32.png) [@san1981](https://www.ruby-forum.com/u/san1981)\
**Post date:** [May 18, 2008, 8:58pm UTC](https://www.ruby-forum.com/t/javascript-validation-for-a-form/137949/1 "2008-05-18T20:58:01Z")

</div>

Hello,

I’ve made a form with a validation system in rails  
(validates\_presence\_of etc) but I’ld like also to make a classic  
validation with an external javascript to have a direct client  
validation without sending to the server. Is it possible?

Thanks you for your help,

---

<div class="post-metadata">

**Author:** ![san1981](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ad7895/32.png) [@san1981](https://www.ruby-forum.com/u/san1981)\
**Post date:** [May 18, 2008, 9:04pm UTC](https://www.ruby-forum.com/t/javascript-validation-for-a-form/137949/2 "2008-05-18T21:04:22Z")

</div>

How about trying live validation?

On Mon, May 19, 2008 at 2:58 AM, san 1981  
[removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/).
> 
> >

–  
Ramon T.

---

<div class="post-metadata">

**Author:** ![san1981](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ad7895/32.png) [@san1981](https://www.ruby-forum.com/u/san1981)\
**Post date:** [May 18, 2008, 9:37pm UTC](https://www.ruby-forum.com/t/javascript-validation-for-a-form/137949/3 "2008-05-18T21:37:18Z")

</div>

Ramon T. wrote:

> How about trying live validation?
> 
> On Mon, May 19, 2008 at 2:58 AM, san 1981  
> [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:
> 
> > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/).

Thanks Tayag, I didn’t know live validation but that seems really  
interesting, I’ll try this.

I’ve yet a question about the classic rails validation… When I add  
“validates\_presence\_of :email”; if the field “email” is empty, when the  
submitting I receive an error message " You have a nil object when you  
didn’t expect it! You might have expected an instance of Array. The  
error occurred while evaluating nil.collect’. If the field “email” is  
filled, the field with select .collect works perfectly?

---

<div class="post-metadata">

**Author:** ![san1981](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/ad7895/32.png) [@san1981](https://www.ruby-forum.com/u/san1981)\
**Post date:** [May 18, 2008, 9:39pm UTC](https://www.ruby-forum.com/t/javascript-validation-for-a-form/137949/4 "2008-05-18T21:39:00Z")

</div>

san 1981 wrote:

> Ramon T. wrote:
> 
> > How about trying live validation?
> > 
> > On Mon, May 19, 2008 at 2:58 AM, san 1981  
> > [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:
> > 
> > > Posted via [http://www.ruby-forum.com/](http://www.ruby-forum.com/).
> 
> Thanks Tayag, I didn’t know live validation but that seems really  
> interesting, I’ll try this.
> 
> I’ve yet a question about the classic rails validation… When I add  
> “validates\_presence\_of :email”; if the field “email” is empty, when the  
> submitting I receive an error message " You have a nil object when you  
> didn’t expect it! You might have expected an instance of Array. The  
> error occurred while evaluating nil.collect’. If the field “email” is  
> filled, the field with select .collect works perfectly?

I’ll say that if the field “email” is filled, the form is well  
submitted. I received the error message only if this field is empty.