# How to carry parameters to a new page?

**URL:** <https://www.ruby-forum.com/t/how-to-carry-parameters-to-a-new-page/51938>\
**Category:** Rails\
**Created:** [January 9, 2006, 2:01pm UTC](https://www.ruby-forum.com/t/how-to-carry-parameters-to-a-new-page/51938 "2006-01-09T14:01:31Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![Dzei](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/76d3ee/32.png) [@Dzei](https://www.ruby-forum.com/u/Dzei)\
**Post date:** [January 9, 2006, 2:01pm UTC](https://www.ruby-forum.com/t/how-to-carry-parameters-to-a-new-page/51938/1 "2006-01-09T14:01:31Z")

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Hello,

I have a page where user can register him/herself to the site.

If the user enters something wrong, or leaves blank textboxes, I want to  
reload the page and tell the user what went wrong. Also the  
textbox-values the user already entered, should be kept in the  
textboxes.

For example, in my user-controller:

if @username.length == 0  
redirect\_to :action =\> ‘registeruser’, :message =\> “You must give an  
username”

This gives the url:  
“/user/registeruser?message=You+must+give+an+username” and I can show  
the message with \<%=h @params[‘message’]%\>.

Is this THE way to go, just add the values from textboxes to the url  
also? Or is there a way I can do this without using the url-parameters?

---

<div class="post-metadata">

**Author:** ![Dzei](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/76d3ee/32.png) [@Dzei](https://www.ruby-forum.com/u/Dzei)\
**Post date:** [January 9, 2006, 3:14pm UTC](https://www.ruby-forum.com/t/how-to-carry-parameters-to-a-new-page/51938/2 "2006-01-09T15:14:45Z")

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You could do:

if @username.length == 0  
@session[:error]=“You must give an username”  
redirect\_to :action =\> ‘registeruser’  
end  
and then use @session[:error] to access the error

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<div class="post-metadata">

**Author:** ![Dzei](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/76d3ee/32.png) [@Dzei](https://www.ruby-forum.com/u/Dzei)\
**Post date:** [January 9, 2006, 4:09pm UTC](https://www.ruby-forum.com/t/how-to-carry-parameters-to-a-new-page/51938/3 "2006-01-09T16:09:02Z")

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Hi,

On 9.1.2006, at 15.01, Dzei wrote:

> For example, in my user-controller:  
> Is this THE way to go, just add the values from textboxes to the url  
> also? Or is there a way I can do this without using the url-  
> parameters?

The Rails way of doing this is not to redirect. If there’s something  
wrong with the input data, just re-display the same form:

in the controller:

@user = User.new(params[:user])

if @user.save  
redirect\_to somewhere\_else  
else  
# the user input was invalid  
flash.now(:error) = “There was a problem with your input”  
render :action =\> “add\_user”  
end

Now the add\_user template (the same you used in the original form  
page) will have an invalid @user object at hand. If you used the  
Rails form helper methods like text\_field (you did, didn’t you?), the  
fields with error will be automatically marked as erroneous. You can  
also display error\_messages\_for, which will output a list of all  
fields that were invalid.

Oh, and you shouldn’t have to do things like

> if @username.length == 0  
> redirect\_to :action =\> ‘registeruser’, :message =\> “You must  
> give an  
> username”

yourself. Validations like this belong to the model and the above-  
mentioned depends on the model validations. See the api docs for  
validations [1] for more info.

//jarkko

[1] [http://api.rubyonrails.com/classes/ActiveRecord/Validations.html](http://api.rubyonrails.com/classes/ActiveRecord/Validations.html)

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<div class="post-metadata">

**Author:** ![Dzei](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/76d3ee/32.png) [@Dzei](https://www.ruby-forum.com/u/Dzei)\
**Post date:** [January 9, 2006, 5:57pm UTC](https://www.ruby-forum.com/t/how-to-carry-parameters-to-a-new-page/51938/4 "2006-01-09T17:57:42Z")

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Thank you all for your answers.

And yes I ordered the Agile Web D. with Rails last week. I hope  
it ships soon. 🙂

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<div class="post-metadata">

**Author:** ![Dzei](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/d/76d3ee/32.png) [@Dzei](https://www.ruby-forum.com/u/Dzei)\
**Post date:** [January 9, 2006, 4:57pm UTC](https://www.ruby-forum.com/t/how-to-carry-parameters-to-a-new-page/51938/5 "2006-01-09T16:57:22Z")

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You should really read Agile Web D. with Rails. Using flash  
messages  
is one of the first things discussed, and if your form was built with  
scaffolding, then the support is already there.