Rails - Feb 2006 - newbie-> help understanding "magic" behavior

I am trying out ROR for the first time[1], and have much PHP poisoning 
to overcome in my mental baggage. That said, I was delighted to find 
that I could make a link from a "show" page to the next record in the 
database by simply adding

	@next_page = Content.find(params["id"].next)

to my content_controller.rb and then constructing a link to it within 
my show.rhtml.

The only definition of the ''next'' method I can find is within
the
''paginator'' class, yet I am not invoking that class as far as
I can
tell. So there''s no problem with next per se, but trying to do the 
opposite (in my mind, anyway) by setting

	@prev_page = Content.find(params["id".previous  (and many, many other
attempts, like prev, or id -1, just to be utterly hacky)

Only gets me errors, and googling has so far not yielded the solution.

Any suggestions? Am I even trying to do this in the Right Place? The 
book has been ordered, before you suggest that...

Thanks,

Walter

1. Mac OS X 10.4.4, Locomotive 1.0.0, ruby 1.8.2 (2004-12-25) 
[powerpc-darwin7.9.0], MySQL 4.1.8-standard for apple-darwin7.6.0 on 
powerpc(Official MySQL-standard binary)

The next method is actually a part of the Integer class. Fire up irb and
type
1.next
And behold! You get 2  :)     So, not a lot of magic, and not a particularly
safe way to get to the next record (may not be a record 2) and so forth. But
this is just on of the nice things about everything being an object in Ruby.
You find a whole bunch of hidden treasures.

Also, if you fire up the rails console (from your rails-app path type `ruby
script/console` and then type
1.day.from_now

Hope this explains some of the mysteries!
-nick

On 2/15/06, Walter Lee Davis <waltd@wdstudio.com>
wrote:
>
> I am trying out ROR for the first time[1], and have much PHP poisoning
> to overcome in my mental baggage. That said, I was delighted to find
> that I could make a link from a "show" page to the next record in
the
> database by simply adding
>
>         @next_page = Content.find(params["id"].next)
>
> to my content_controller.rb and then constructing a link to it within
> my show.rhtml.
>
> The only definition of the ''next'' method I can find is
within the
> ''paginator'' class, yet I am not invoking that class as
far as I can
> tell. So there''s no problem with next per se, but trying to do the
> opposite (in my mind, anyway) by setting
>
>         @prev_page = Content.find(params["id".previous  (and
many, many
> other
> attempts, like prev, or id -1, just to be utterly hacky)
>
> Only gets me errors, and googling has so far not yielded the solution.
>
> Any suggestions? Am I even trying to do this in the Right Place? The
> book has been ordered, before you suggest that...
>
> Thanks,
>
> Walter
>
> 1. Mac OS X 10.4.4, Locomotive 1.0.0, ruby 1.8.2 (2004-12-25)
> [powerpc-darwin7.9.0], MySQL 4.1.8-standard for apple-darwin7.6.0 on
> powerpc(Official MySQL-standard binary)
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
http://wrath.rubyonrails.org/pipermail/rails/attachments/20060215/380c3b93/attachment-0001.html

Thanks for the clue. I am now trying to use the Pagination module to 
figure this out, but it''s not getting me much further. I can either get
a lovely syntax error, or a Next link to record 2 and a Previous link 
to record null, but nothing meaningful.

Any further clues how I might show a single page (not a list) 
representing a single record row, and then automagically get the next 
and previous record ids, sorted by id?

Thanks in advance,

Walter

On Feb 15, 2006, at 9:53 AM, Nick Stuart wrote:
> The next method is actually a part of the Integer class. Fire up irb 
> and type
> 1.next
> And behold! You get 2? :)???? So, not a lot of magic, and not a 
> particularly safe way to get to the next record (may not be a record 
> 2) and so forth. But this is just on of the nice things about 
> everything being an object in Ruby. You find a whole bunch of hidden 
> treasures.
>
> Also, if you fire up the rails console (from your rails-app path type 
> `ruby script/console` and then type
> 1.day.from_now
>
> Hope this explains some of the mysteries!
> -nick
>
>  On 2/15/06, Walter Lee Davis <waltd@wdstudio.com> wrote:
>> to overcome in my mental baggage. That said, I was delighted to find
>> that I could make a link from a "show" page to the next
record in the
>> database by simply adding
>>
>> ????????@next_page = Content.find(params["id"].next)
>>
>> to my content_controller.rb and then constructing a link to it within
>> my show.rhtml.
>>
>> The only definition of the ''next'' method I can find
is within the
>> ''paginator'' class, yet I am not invoking that class
as far as I can
>> tell. So there''s no problem with next per se, but trying to do
the
>> opposite (in my mind, anyway) by setting
>>
>> ????????@prev_page = Content.find (params["id".previous??(and
many,
>> many other
>> attempts, like prev, or id -1, just to be utterly hacky)
>>
>> Only gets me errors, and googling has so far not yielded the solution.
>>
>> Any suggestions? Am I even trying to do this in the Right Place? The
>> book has been ordered, before you suggest that...
>>
>> Thanks,
>>
>> Walter
>>
>> 1. Mac OS X 10.4.4, Locomotive 1.0.0, ruby 1.8.2 (2004-12-25)
>> [powerpc-darwin7.9.0], MySQL 4.1.8-standard for apple-darwin7.6.0 on
>> powerpc(Official MySQL-standard binary)
>>
>> _______________________________________________
>> Rails mailing list
>> Rails@lists.rubyonrails.org
>>  http://lists.rubyonrails.org/mailman/listinfo/rails
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails

Forgot to add -- this is when I am starting from an id firmly in the 
MIDDLE of the table.

Walter

On Feb 15, 2006, at 11:18 AM, Walter Lee Davis wrote:
> Thanks for the clue. I am now trying to use the Pagination module to 
> figure this out, but it''s not getting me much further. I can
either
> get a lovely syntax error, or a Next link to record 2 and a Previous 
> link to record null, but nothing meaningful.
>
> Any further clues how I might show a single page (not a list) 
> representing a single record row, and then automagically get the next 
> and previous record ids, sorted by id?
>
> Thanks in advance,
>
> Walter
>
> On Feb 15, 2006, at 9:53 AM, Nick Stuart wrote:
>
>> The next method is actually a part of the Integer class. Fire up irb 
>> and type
>> 1.next
>> And behold! You get 2? :)???? So, not a lot of magic, and not a 
>> particularly safe way to get to the next record (may not be a record 
>> 2) and so forth. But this is just on of the nice things about 
>> everything being an object in Ruby. You find a whole bunch of hidden 
>> treasures.
>>
>> Also, if you fire up the rails console (from your rails-app path type 
>> `ruby script/console` and then type
>> 1.day.from_now
>>
>> Hope this explains some of the mysteries!
>> -nick
>>
>>  On 2/15/06, Walter Lee Davis <waltd@wdstudio.com> wrote:
>>> to overcome in my mental baggage. That said, I was delighted to
find
>>> that I could make a link from a "show" page to the next
record in the
>>> database by simply adding
>>>
>>> ????????@next_page = Content.find(params["id"].next)
>>>
>>> to my content_controller.rb and then constructing a link to it
within
>>> my show.rhtml.
>>>
>>> The only definition of the ''next'' method I can
find is within the
>>> ''paginator'' class, yet I am not invoking that
class as far as I can
>>> tell. So there''s no problem with next per se, but trying
to do the
>>> opposite (in my mind, anyway) by setting
>>>
>>> ????????@prev_page = Content.find
(params["id".previous??(and many,
>>> many other
>>> attempts, like prev, or id -1, just to be utterly hacky)
>>>
>>> Only gets me errors, and googling has so far not yielded the 
>>> solution.
>>>
>>> Any suggestions? Am I even trying to do this in the Right Place?
The
>>> book has been ordered, before you suggest that...
>>>
>>> Thanks,
>>>
>>> Walter
>>>
>>> 1. Mac OS X 10.4.4, Locomotive 1.0.0, ruby 1.8.2 (2004-12-25)
>>> [powerpc-darwin7.9.0], MySQL 4.1.8-standard for apple-darwin7.6.0
on
>>> powerpc(Official MySQL-standard binary)
>>>
>>> _______________________________________________
>>> Rails mailing list
>>> Rails@lists.rubyonrails.org
>>>  http://lists.rubyonrails.org/mailman/listinfo/rails
>> _______________________________________________
>> Rails mailing list
>> Rails@lists.rubyonrails.org
>> http://lists.rubyonrails.org/mailman/listinfo/rails
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails

I think you are getting confused on the use of the Paginator stuff. This is
really meant to be used when you are display a big list of things. It allows
to easily split a list of 100 objects into a list of 10 pages showing 10
objects each, and you can easily move back and forth between them.

It looks like, from what you''ve posted here you are displaying a single
object and then want to move to the next/previous, correct? If thats the
case, take a look at the "acts_as_list" method in the api. It will let
you
easily put actions in that would look something like:

def next
  current = Object.find params[:id]
  @prev = current.lower_item
end

and so on a so forth. Check it out, and see what you like.

Hope this helps!
-Nick
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
http://wrath.rubyonrails.org/pipermail/rails/attachments/20060215/653e6180/attachment.html

Thanks! I looked in the documentation, and this looks promising, but I 
am having trouble implementing your example. What''s confusing me is 
that you have defined a new view here with def next, right? Where would 
you slot this code into an existing view:

def mypage
	@title = Content.find(params["id"])
end

Thanks again,

Walter

On Feb 15, 2006, at 11:57 AM, Nick Stuart wrote:
> I think you are getting confused on the use of the Paginator stuff. 
> This is really meant to be used when you are display a big list of 
> things. It allows to easily split a list of 100 objects into a list of 
> 10 pages showing 10 objects each, and you can easily move back and 
> forth between them.
>
> It looks like, from what you''ve posted here you are displaying a 
> single object and then want to move to the next/previous, correct? If 
> thats the case, take a look at the "acts_as_list" method in the
api.
> It will let you easily put actions in that would look something like:
>
> def next
> ? current = Object.find params[:id]
> ? @prev = current.lower_item
> end
>
> and so on a so forth. Check it out, and see what you like.
>
> Hope this helps!
> -Nick
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails

Ok, so step through this. It looks like you want to display a "book"
style
site with pages, each with a possible next/prev page.

I would have my controller simply load the page, and have two links for the
prev/next actions on the page itself. You could even ''cheat''
and just have
one page loading action:
controller stuff =>

def show_page
    @page = Page.find params[:id]
end

view stuff =>

<%= link_to("previous", :id => @page.higher_item) if
@page.higher_item %>
<%= link_to("next", :id => @page.lower_item) if @page.lower_item
%>

(might need to play with the method calls a little a bit to make sense for
you, the wording for acts_as_list is a bit weird in this case)

Let me know if I''ve assumed anything wrong here!

-Nick

On 2/15/06, Walter Lee Davis <waltd@wdstudio.com>
wrote:
>
> Thanks! I looked in the documentation, and this looks promising, but I
> am having trouble implementing your example. What''s confusing me
is
> that you have defined a new view here with def next, right? Where would
> you slot this code into an existing view:
>
> def mypage
>         @title = Content.find(params["id"])
> end
>
> Thanks again,
>
> Walter
>
> On Feb 15, 2006, at 11:57 AM, Nick Stuart wrote:
>
> > I think you are getting confused on the use of the Paginator stuff.
> > This is really meant to be used when you are display a big list of
> > things. It allows to easily split a list of 100 objects into a list of
> > 10 pages showing 10 objects each, and you can easily move back and
> > forth between them.
> >
> > It looks like, from what you''ve posted here you are
displaying a
> > single object and then want to move to the next/previous, correct? If
> > thats the case, take a look at the "acts_as_list" method in
the api.
> > It will let you easily put actions in that would look something like:
> >
> > def next
> > current = Object.find params[:id]
> > @prev = current.lower_item
> > end
> >
> > and so on a so forth. Check it out, and see what you like.
> >
> > Hope this helps!
> > -Nick
> > _______________________________________________
> > Rails mailing list
> > Rails@lists.rubyonrails.org
> > http://lists.rubyonrails.org/mailman/listinfo/rails
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL:
http://wrath.rubyonrails.org/pipermail/rails/attachments/20060215/77304eb7/attachment.html

Well, that gets rid of the previous error, but the links don''t show up 
now either. If I get rid of the "if @content.higher_item" test, then I
get links that don''t work (they don''t have a record number
following
them).

Walter

On Feb 15, 2006, at 2:12 PM, Nick Stuart wrote:
> Ok, so step through this. It looks like you want to display a
"book"
> style site with pages, each with a possible next/prev page.
>
> I would have my controller simply load the page, and have two links 
> for the prev/next actions on the page itself. You could even
''cheat''
> and just have one page loading action:
> controller stuff =>
>
> def show_page
> ??? @page = Page.find params[:id]
> end
>
> view stuff =>
>
> <%= link_to("previous", :id => @page.higher_item) if
@page.higher_item
> %>
> <%= link_to("next", :id => @ page.lower_item) if
@page.lower_item %>
>
> (might need to play with the method calls a little a bit to make sense 
> for you, the wording for acts_as_list is a bit weird in this case)
>
> Let me know if I''ve assumed anything wrong here!
>
> -Nick
>
> On 2/15/06, Walter Lee Davis <waltd@wdstudio.com> wrote:
>> am having trouble implementing your example. What''s confusing
me is
>> that you have defined a new view here with def next, right? Where 
>> would
>> you slot this code into an existing view:
>>
>> def mypage
>> ????????@title = Content.find(params["id"])
>> end
>>
>> Thanks again,
>>
>> Walter
>>
>> On Feb 15, 2006, at 11:57 AM, Nick Stuart wrote:
>>
>> > I think you are getting confused on the use of the Paginator
stuff.
>> > This is really meant to be used when you are display a big list of
>> > things. It allows to easily split a list of 100 objects into a
list
>> of
>> > 10 pages showing 10 objects each, and you can easily move back and
>> > forth between them.
>> >
>> > It looks like, from what you''ve posted here you are
displaying a
>> > single object and then want to move to the next/previous, correct?
>> If
>> > thats the case, take a look at the "acts_as_list" method
in the api.
>> > It will let you easily put actions in that would look something 
>> like:
>> >
>> > def next
>> > current = Object.find params[:id]
>> > @prev = current.lower_item
>> > end
>> >
>> > and so on a so forth. Check it out, and see what you like.
>> >
>> > Hope this helps!
>> > -Nick
>> > _______________________________________________
>> > Rails mailing list
>> > Rails@lists.rubyonrails.org
>> > http://lists.rubyonrails.org/mailman/listinfo/rails
>>
>> _______________________________________________
>> Rails mailing list
>>  Rails@lists.rubyonrails.org
>> http://lists.rubyonrails.org/mailman/listinfo/rails
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails

Sorry, I just realized that this works perfectly as long as you add a 
column named position, and *critical, missing step here* populate that 
column with the contents of the id column.

I had tried just setting the position column to BE the id column in my 
controller, but that failed for some reason. I''ll have to go back and 
try again to be sure.

Thanks for the wonderful help.

Walter

On Feb 15, 2006, at 2:56 PM, Walter Lee Davis wrote:
> Well, that gets rid of the previous error, but the links don''t
show up
> now either. If I get rid of the "if @content.higher_item" test,
then I
> get links that don''t work (they don''t have a record
number following
> them).
>
> Walter
>
> On Feb 15, 2006, at 2:12 PM, Nick Stuart wrote:
>
>> Ok, so step through this. It looks like you want to display a
"book"
>> style site with pages, each with a possible next/prev page.
>>
>> I would have my controller simply load the page, and have two links 
>> for the prev/next actions on the page itself. You could even
''cheat''
>> and just have one page loading action:
>> controller stuff =>
>>
>> def show_page
>> ??? @page = Page.find params[:id]
>> end
>>
>> view stuff =>
>>
>> <%= link_to("previous", :id => @page.higher_item) if 
>> @page.higher_item %>
>> <%= link_to("next", :id => @ page.lower_item) if
@page.lower_item %>
>>
>> (might need to play with the method calls a little a bit to make 
>> sense for you, the wording for acts_as_list is a bit weird in this 
>> case)
>>
>> Let me know if I''ve assumed anything wrong here!
>>
>> -Nick
>>
>> On 2/15/06, Walter Lee Davis <waltd@wdstudio.com> wrote:
>>> am having trouble implementing your example. What''s
confusing me is
>>> that you have defined a new view here with def next, right? Where 
>>> would
>>> you slot this code into an existing view:
>>>
>>> def mypage
>>> ????????@title = Content.find(params["id"])
>>> end
>>>
>>> Thanks again,
>>>
>>> Walter
>>>
>>> On Feb 15, 2006, at 11:57 AM, Nick Stuart wrote:
>>>
>>> > I think you are getting confused on the use of the Paginator
stuff.
>>> > This is really meant to be used when you are display a big
list of
>>> > things. It allows to easily split a list of 100 objects into a
>>> list of
>>> > 10 pages showing 10 objects each, and you can easily move back
and
>>> > forth between them.
>>> >
>>> > It looks like, from what you''ve posted here you are
displaying a
>>> > single object and then want to move to the next/previous,
correct?
>>> If
>>> > thats the case, take a look at the "acts_as_list"
method in the
>>> api.
>>> > It will let you easily put actions in that would look
something
>>> like:
>>> >
>>> > def next
>>> > current = Object.find params[:id]
>>> > @prev = current.lower_item
>>> > end
>>> >
>>> > and so on a so forth. Check it out, and see what you like.
>>> >
>>> > Hope this helps!
>>> > -Nick
>>> > _______________________________________________
>>> > Rails mailing list
>>> > Rails@lists.rubyonrails.org
>>> > http://lists.rubyonrails.org/mailman/listinfo/rails
>>>
>>> _______________________________________________
>>> Rails mailing list
>>>  Rails@lists.rubyonrails.org
>>> http://lists.rubyonrails.org/mailman/listinfo/rails
>> _______________________________________________
>> Rails mailing list
>> Rails@lists.rubyonrails.org
>> http://lists.rubyonrails.org/mailman/listinfo/rails
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails

Yes, that''s part of the contract for acts_as_list, it needs a position
column. Also, setting the position to be the id is a bad idea. what
happens when you want to possibly move a page? or insert a new page in
between other pages?

Glad you got it working!
-Nick

On 2/15/06, Walter Lee Davis <waltd@wdstudio.com>
wrote:
> Sorry, I just realized that this works perfectly as long as you add a
> column named position, and *critical, missing step here* populate that
> column with the contents of the id column.
>
> I had tried just setting the position column to BE the id column in my
> controller, but that failed for some reason. I''ll have to go back
and
> try again to be sure.
>
> Thanks for the wonderful help.
>
> Walter
>
> On Feb 15, 2006, at 2:56 PM, Walter Lee Davis wrote:
>
> > Well, that gets rid of the previous error, but the links
don''t show up
> > now either. If I get rid of the "if @content.higher_item"
test, then I
> > get links that don''t work (they don''t have a record
number following
> > them).
> >
> > Walter
> >
> > On Feb 15, 2006, at 2:12 PM, Nick Stuart wrote:
> >
> >> Ok, so step through this. It looks like you want to display a
"book"
> >> style site with pages, each with a possible next/prev page.
> >>
> >> I would have my controller simply load the page, and have two
links
> >> for the prev/next actions on the page itself. You could even
''cheat''
> >> and just have one page loading action:
> >> controller stuff =>
> >>
> >> def show_page
> >> @page = Page.find params[:id]
> >> end
> >>
> >> view stuff =>
> >>
> >> <%= link_to("previous", :id => @page.higher_item)
if
> >> @page.higher_item %>
> >> <%= link_to("next", :id => @ page.lower_item) if
@page.lower_item %>
> >>
> >> (might need to play with the method calls a little a bit to make
> >> sense for you, the wording for acts_as_list is a bit weird in this
> >> case)
> >>
> >> Let me know if I''ve assumed anything wrong here!
> >>
> >> -Nick
> >>
> >> On 2/15/06, Walter Lee Davis <waltd@wdstudio.com> wrote:
> >>> am having trouble implementing your example. What''s
confusing me is
> >>> that you have defined a new view here with def next, right?
Where
> >>> would
> >>> you slot this code into an existing view:
> >>>
> >>> def mypage
> >>> @title = Content.find(params["id"])
> >>> end
> >>>
> >>> Thanks again,
> >>>
> >>> Walter
> >>>
> >>> On Feb 15, 2006, at 11:57 AM, Nick Stuart wrote:
> >>>
> >>> > I think you are getting confused on the use of the
Paginator stuff.
> >>> > This is really meant to be used when you are display a
big list of
> >>> > things. It allows to easily split a list of 100 objects
into a
> >>> list of
> >>> > 10 pages showing 10 objects each, and you can easily move
back and
> >>> > forth between them.
> >>> >
> >>> > It looks like, from what you''ve posted here you
are displaying a
> >>> > single object and then want to move to the next/previous,
correct?
> >>> If
> >>> > thats the case, take a look at the
"acts_as_list" method in the
> >>> api.
> >>> > It will let you easily put actions in that would look
something
> >>> like:
> >>> >
> >>> > def next
> >>> > current = Object.find params[:id]
> >>> > @prev = current.lower_item
> >>> > end
> >>> >
> >>> > and so on a so forth. Check it out, and see what you
like.
> >>> >
> >>> > Hope this helps!
> >>> > -Nick
> >>> > _______________________________________________
> >>> > Rails mailing list
> >>> > Rails@lists.rubyonrails.org
> >>> > http://lists.rubyonrails.org/mailman/listinfo/rails
> >>>
> >>> _______________________________________________
> >>> Rails mailing list
> >>>  Rails@lists.rubyonrails.org
> >>> http://lists.rubyonrails.org/mailman/listinfo/rails
> >> _______________________________________________
> >> Rails mailing list
> >> Rails@lists.rubyonrails.org
> >> http://lists.rubyonrails.org/mailman/listinfo/rails
> >
> > _______________________________________________
> > Rails mailing list
> > Rails@lists.rubyonrails.org
> > http://lists.rubyonrails.org/mailman/listinfo/rails
>
> _______________________________________________
> Rails mailing list
> Rails@lists.rubyonrails.org
> http://lists.rubyonrails.org/mailman/listinfo/rails
>