# Re-initialising page after validation fails

**URL:** <https://www.ruby-forum.com/t/re-initialising-page-after-validation-fails/173424>\
**Category:** Rails\
**Created:** [August 8, 2009, 1:20pm UTC](https://www.ruby-forum.com/t/re-initialising-page-after-validation-fails/173424 "2009-08-08T13:20:03Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![akm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/57b2e6/32.png) [@akm](https://www.ruby-forum.com/u/akm)\
**Post date:** [August 8, 2009, 1:20pm UTC](https://www.ruby-forum.com/t/re-initialising-page-after-validation-fails/173424/1 "2009-08-08T13:20:03Z")

</div>

Hi,

I have a controller and two of the actions in it are as follows:

# GET /bids/new

# GET /bids/new.xml

def new  
@bid = Bid.new  
@auctionItems = AuctionItem.find(:all)

```
respond_to do |format|
  format.html # new.html.erb
  format.xml { render :xml => @bid }
end

```

end

# GET /bids/1/edit

def edit  
@bid = Bid.find(params[:id])  
end

# POST /bids

# POST /bids.xml

def create  
@bid = Bid.new(params[:bid])

```
respond_to do |format|
  if @bid.save
    flash[:notice] = 'Bid was successfully created.'
    format.html { redirect_to(@bid) }
    format.xml { render :xml => @bid, :status => :created,

```

:location =\> @bid }  
else  
format.html { render :action =\> “new” }  
format.xml { render :xml =\> @bid.errors, :status =\>  
:unprocessable\_entity }  
end  
end  
end

The new.html.erb contains this line:

\<%= f.select(:auction\_item\_id, @auctionItems.collect {|i| [ i.title,  
i.id ]

Which populates a select with the auctionItems fetched in the new  
action.

If validation fails in the “create”, I get an error something like:

NoMethodError in Bids#create

Showing app/views/bids/new.html.erb where line #8 raised:

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

Extracted source (around line #8):

5:  
6:  
7:

8: \<%= f.select(:auction\_item\_id, @auctionItems.collect {|i| [ i.title,  
i.id ] }, { :include\_blank =\> true }) %\>  
9:

  
10:  
11: 

I am guessing this is because the auctionItems is not repopulated for  
this request.

So, does this:

```
    format.html { render :action => "new" }

```

Mean it only displays new.html.erb, and not re-runs the “new” action?

What is the best way to ensure that @auctionItems gets repopulated. I  
suppose I modify create like this:

def create  
@bid = Bid.new(params[:bid])

```
respond_to do |format|
  if @bid.save
    flash[:notice] = 'Bid was successfully created.'
    format.html { redirect_to(@bid) }
    format.xml { render :xml => @bid, :status => :created,

```

:location =\> @bid }  
else  
@auctionItems = AuctionItem.find(:all)  
format.html { render :action =\> “new” }  
format.xml { render :xml =\> @bid.errors, :status =\>  
:unprocessable\_entity }  
end  
end  
end

But it doesn’t seem the best practice. Is there a better way to do  
this? I have seen some mention of “Helpers” - is this something they  
could be used for?

Many thanks,  
Andrew.

---

<div class="post-metadata">

**Author:** ![akm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/57b2e6/32.png) [@akm](https://www.ruby-forum.com/u/akm)\
**Post date:** [August 9, 2009, 5:55pm UTC](https://www.ruby-forum.com/t/re-initialising-page-after-validation-fails/173424/2 "2009-08-09T17:55:56Z")

</div>

On Aug 8, 7:20 am, Andrew M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> Extracted source (around line #8):  
> I am guessing this is because the auctionItems is not repopulated for  
> this request.
> 
> So, does this:
> 
> ```
> format.html { render :action => "new" }
> 
> ```
> 
> Mean it only displays new.html.erb, and not re-runs the “new” action?

Yep - all that does is render the selected template. The idea is that  
that the form will be redisplayed with the contents of @bid.

> ```
> format.html { redirect_to(@bid) }
> 
> ```
> 
> But it doesn’t seem the best practice. Is there a better way to do  
> this? I have seen some mention of “Helpers” - is this something they  
> could be used for?

This is a very typical use of helpers - you could put this code into  
app/helpers/bid\_helper.rb:

def auction\_select(form)  
form.select(:auction\_item\_id, AuctionItem.all.collect {|i|  
[ i.title,  
i.id ] })  
end

and then call it from your views as:

\<%= auction\_select(f) %\>

It tidies things up, and then when you need to select an auction  
someplace else, it can be reused.

BTW, mixed-case variable names are nonstandard in Rails - normally,  
you use underscored names (@auction\_items rather than @auctionItems).  
No real difference, but it looks odd to experienced programmers.

–Matt J.

---

<div class="post-metadata">

**Author:** ![akm](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/57b2e6/32.png) [@akm](https://www.ruby-forum.com/u/akm)\
**Post date:** [August 10, 2009, 12:53am UTC](https://www.ruby-forum.com/t/re-initialising-page-after-validation-fails/173424/3 "2009-08-10T00:53:14Z")

</div>

Thanks Matt - that sounds like the solution I am after. Also thanks for  
the advice re variable names. I am coming to Ruby from Java and have a  
bit to learn in that regard. 🙂

Matt J. wrote:

> This is a very typical use of helpers - you could put this code into  
> app/helpers/bid\_helper.rb:
> 
> def auction\_select(form)  
> form.select(:auction\_item\_id, AuctionItem.all.collect {|i|  
> [ i.title,  
> i.id ] })  
> end
> 
> and then call it from your views as:
> 
> \<%= auction\_select(f) %\>
> 
> It tidies things up, and then when you need to select an auction  
> someplace else, it can be reused.
> 
> BTW, mixed-case variable names are nonstandard in Rails - normally,  
> you use underscored names (@auction\_items rather than @auctionItems).  
> No real difference, but it looks odd to experienced programmers.
> 
> –Matt J.