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Kim

2007-Jan-31 00:45 UTC

Using hash.keys - why doesn''t it display in order created

I am using .keys on a hash  to create an array that is than displayed 
in a view with .each - why does it not display  the keys in the order 
added to the hash?

I would like to controll how the array is displayed - I want the 
checkboxes to display like I added them to the hash, but it doesn''t - 
I can''t figure out how it is displayed, when I change the order of the 
hash it does little to the view.

Please help - thanks, K

Code

Controller
-----------------
# creates my hash
def mod_types
    {''Learning Objects'' => LearnObjResource, ''RSS
Feed'' =>
RssResource, ''Blank Module'' =>
BlankResource,''Course Librarian'' =>
LibResource, ''Professor Information'' => InstResource,
''Course
Assignment'' => AssignResource, ''Style Guides''
=> StyleResource,
''Plagiarism Information'' => PlagResource,
''Instructor Recommends'' =>
RecomResource, ''Course Reserves'' => ReserveResorce }
  end

#action for view
def list_modules
    @mods = @user.modules
    @list = mod_types.keys # here I am making an array out of the hash
    if request.post?
      redirect_to :action => "manage_modules"
    end
  end

View
-----------
...
<%@list.each do |mod|%>
            <%= check_box_tag("mods[]", mod ,false, {:class => 
"class"}) %>
            <%= mod%><br />
        <%end%>


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Ezra Zygmuntowicz

2007-Jan-31 00:53 UTC

head link

Re: Using hash.keys - why doesn''t it display in order created

Hi~

On Jan 30, 2007, at 4:45 PM, Kim wrote:
>
> I am using .keys on a hash  to create an array that is than displayed
> in a view with .each - why does it not display  the keys in the order
> added to the hash?
>
> I would like to controll how the array is displayed - I want the
> checkboxes to display like I added them to the hash, but it
doesn''t -
> I can''t figure out how it is displayed, when I change the order of
the
> hash it does little to the view.
>
> Please help - thanks, K
>
> Code
>
> Controller
> -----------------
> # creates my hash
> def mod_types
>     {''Learning Objects'' => LearnObjResource,
''RSS Feed'' =>
> RssResource, ''Blank Module'' =>
BlankResource,''Course Librarian'' =>
> LibResource, ''Professor Information'' => InstResource,
''Course
> Assignment'' => AssignResource, ''Style Guides''
=> StyleResource,
> ''Plagiarism Information'' => PlagResource,
''Instructor Recommends'' =>
> RecomResource, ''Course Reserves'' => ReserveResorce }
>   end
>
> #action for view
> def list_modules
>     @mods = @user.modules
>     @list = mod_types.keys # here I am making an array out of the hash
>     if request.post?
>       redirect_to :action => "manage_modules"
>     end
>   end
>
> View
> -----------
> ...
> <%@list.each do |mod|%>
>             <%= check_box_tag("mods[]", mod ,false, {:class
=>
> "class"}) %>
>             <%= mod%><br />
>         <%end%>

	Hashes are unordered data structures. You can''t get them in order  
inserted with a normal hash. You will have to use an array or google  
for an ordered hash class for ruby.

Cheers-

-- Ezra Zygmuntowicz 
-- Lead Rails Evangelist
-- ez-NLltGlunAUd/unjJdyJNww@public.gmane.org
-- Engine Yard, Serious Rails Hosting
-- (866) 518-YARD (9273)



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Bill Walton

2007-Jan-31 00:57 UTC

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Re: Using hash.keys - why doesn''t it display in order created

Hi Kim,

Hashes are, by definition, unordered.  Ruby does provide the sort method for 
Hash, though.  See pg. 499 in Pickaxe for more info.

hth
Bill 



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Kim

2007-Jan-31 18:10 UTC

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Re: Using hash.keys - why doesn''t it display in order created

I don''t want to sort the hash - I want to determine the order the
values from the hash are displayed. I can''t use an array because of
what I need to be able to do after users select values.

The view uses the keys form the hash - is there any way that I can
controll the order they are displayed?

On Jan 30, 4:57 pm, "Bill Walton"
<bill.wal...-xwVYE8SWAR3R7s880joybQ@public.gmane.org>
wrote:> Hi Kim,
>
> Hashes are, by definition, unordered.  Ruby does provide the sort method
for
> Hash, though.  See pg. 499 in Pickaxe for more info.
>
> hth
> Bill

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Chris Hall

2007-Jan-31 18:57 UTC

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Re: Using hash.keys - why doesn''t it display in order created

as stated previously, Hash.sort, which you don''t want to do, so then
the answer is no, that''s not to say you can''t roll your own
solution.

off the top of my head...

def mod_types
  [ { key1 => val1 }, {key2 => val2}, ...]
end

def list_modules
  ...
  @list = mod_types.map { |mod_type| mod_type.keys.first }
  ...
end

your view shouldn''t have to change.

i would imagine it wouldn''t take much to modify whatever it is you are
doing with users, but since you didn''t provide any details on that, I
can''t provide any possible solutions.



On 1/31/07, Kim <Kim.Griggs-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:>
> I don''t want to sort the hash - I want to determine the order the
> values from the hash are displayed. I can''t use an array because
of
> what I need to be able to do after users select values.
>
> The view uses the keys form the hash - is there any way that I can
> controll the order they are displayed?
>
> On Jan 30, 4:57 pm, "Bill Walton"
<bill.wal...-xwVYE8SWAR3R7s880joybQ@public.gmane.org> wrote:
> > Hi Kim,
> >
> > Hashes are, by definition, unordered.  Ruby does provide the sort
method for
> > Hash, though.  See pg. 499 in Pickaxe for more info.
> >
> > hth
> > Bill
>
>
> >
>
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Benjamin Ritcey

2007-Jan-31 18:57 UTC

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Re: Using hash.keys - why doesn''t it display in order created

Kim wrote:> I don''t want to sort the hash - I want to determine the order the
> values from the hash are displayed. I can''t use an array because
of
> what I need to be able to do after users select values.
> 
> The view uses the keys form the hash - is there any way that I can
> controll the order they are displayed?
> 
AFAIK, not out of the box, but there are ordered hash implementations
available;  check out the Dictionary class from Ruby Facets
(http://facets.rubyforge.org/api/more/classes/Dictionary.html).

Grab the code from

http://facets.rubyforge.org/repo/lib/facets/more/dictionary.rb

and you can use it in your app (drop it in ''lib'' and require
it as needed).

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Kim

2007-Jan-31 20:13 UTC

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Re: Using hash.keys - why doesn''t it display in order created

Dictionary looks good except it does not have some of the methods that
hash has that I need - thanks

I went with hash.keys.sort - not really what I want but at least it is
in alphabetically order.



On Jan 31, 10:57 am, Benjamin Ritcey
<brit...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
wrote:> Kim wrote:
> > I don''t want to sort the hash - I want to determine the order
the
> > values from the hash are displayed. I can''t use an array
because of
> > what I need to be able to do after users select values.
>
> > The view uses the keys form the hash - is there any way that I can
> > controll the order they are displayed?
>
> AFAIK, not out of the box, but there are ordered hash implementations
> available;  check out the Dictionary class from Ruby Facets
> (http://facets.rubyforge.org/api/more/classes/Dictionary.html).
>
> Grab the code from
>
> http://facets.rubyforge.org/repo/lib/facets/more/dictionary.rb
>
> and you can use it in your app (drop it in ''lib'' and
require it as needed).

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