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Daniel Higginbotham

2006-Apr-16 03:17 UTC

[Rails] variable variables?

Hi everyone,

Does Ruby support variable variables like PHP
(http://www.php.net/manual/en/language.variables.variable.php)? Or do I have
to use eval, like

some_hash.each_pair{|key, pair|
	eval "#{key} = #{value}"
}

Or is there some other way?

I''m actually trying to figure this out in order to use ez_where to
create
its conditions from a hash, so if this isn''t even necessary could
someone
let me know?

Thanks,
Daniel

Ezra Zygmuntowicz

2006-Apr-16 03:27 UTC

head link

[Rails] variable variables?

On Apr 15, 2006, at 8:17 PM, Daniel Higginbotham wrote:
> Hi everyone,
>
> Does Ruby support variable variables like PHP
> (http://www.php.net/manual/en/language.variables.variable.php)? Or  
> do I have
> to use eval, like
>
> some_hash.each_pair{|key, pair|
> 	eval "#{key} = #{value}"
> }
>
> Or is there some other way?
>
> I''m actually trying to figure this out in order to use ez_where to
> create
> its conditions from a hash, so if this isn''t even necessary could
> someone
> let me know?
>
> Thanks,
> Daniel
Daniel-

	There is already support for hash.to_sql and other niceties included  
in ez_where. Like so:

class Hash #:nodoc:
   def to_sql(param = ''AND'')
     map { |key,value| key.to_s+'' = ''+ActiveRecord::Base.send 
(:sanitize, value) }.join('' ''+param+'' '')
   end

   def to_conditions(param = ''AND'')
     [map { |k, v| k.to_s+'' = ?'' }.join(''
''+param+'' ''), *values]
   end

   alias :to_sql_conditions :to_conditions
   def to_named_conditions(param = ''AND'')
     [map { |k, v| k.to_s+'' = :''+k }.join(''
''+param+'' ''),
self.symbolize_keys]
   end

end

Look in lib/hash.rb for this. Also the best way to see what that  
plugin is capable of is looking at the test suite. The  
ez_where_tests.rb file in the plugin is 700 lines long and exercises  
all the capabilities of the plugin. So you can see many many sample  
codes using the plugin in that tests file. Its the most complete  
documentation on it right now ;)

Cheers-
-Ezra

Daniel Higginbotham

2006-Apr-16 04:10 UTC

head link

[Rails] variable variables?

Hi Ezra,

Thanks for your response!

Let''s say I''m trying to collect old gambling debts and want to
find people
who owe me money within a range of values, and  who live in certain cities.
My hash looks something like

search {
	:location_ids => [0, 8, 10]
	:amount_owed => 
		{:from => 5000, :to => 10000}
	:still_alive => ''true''
}

I''ve looked through the tests file and wasn''t able to gain any
insight into
how I could convert a hash like this into a nice string of conditions.
I''m
imagining something like, to start with,

cond = Caboose::EZ::Condition.new :chumps do
	search.each_pair {|key, value|
		if defined? value[:from]
			eval "#{key} >= #{value[:from]}"
			next
		end
	end
end

But the more I look at that code the more ridiculous it seems. Any ideas?

Thanks again for your help!

Daniel

-----Original Message-----
From: rails-bounces@lists.rubyonrails.org
[mailto:rails-bounces@lists.rubyonrails.org] On Behalf Of Ezra Zygmuntowicz
Sent: Saturday, April 15, 2006 5:28 PM
To: rails@lists.rubyonrails.org
Subject: Re: [Rails] variable variables?

On Apr 15, 2006, at 8:17 PM, Daniel Higginbotham wrote:
> Hi everyone,
>
> Does Ruby support variable variables like PHP
> (http://www.php.net/manual/en/language.variables.variable.php)? Or  
> do I have
> to use eval, like
>
> some_hash.each_pair{|key, pair|
> 	eval "#{key} = #{value}"
> }
>
> Or is there some other way?
>
> I''m actually trying to figure this out in order to use ez_where to
> create
> its conditions from a hash, so if this isn''t even necessary could
> someone
> let me know?
>
> Thanks,
> Daniel
Daniel-

	There is already support for hash.to_sql and other niceties included

in ez_where. Like so:

class Hash #:nodoc:
   def to_sql(param = ''AND'')
     map { |key,value| key.to_s+'' = ''+ActiveRecord::Base.send 
(:sanitize, value) }.join('' ''+param+'' '')
   end

   def to_conditions(param = ''AND'')
     [map { |k, v| k.to_s+'' = ?'' }.join(''
''+param+'' ''), *values]
   end

   alias :to_sql_conditions :to_conditions
   def to_named_conditions(param = ''AND'')
     [map { |k, v| k.to_s+'' = :''+k }.join(''
''+param+'' ''),
self.symbolize_keys]
   end

end

Look in lib/hash.rb for this. Also the best way to see what that  
plugin is capable of is looking at the test suite. The  
ez_where_tests.rb file in the plugin is 700 lines long and exercises  
all the capabilities of the plugin. So you can see many many sample  
codes using the plugin in that tests file. Its the most complete  
documentation on it right now ;)

Cheers-
-Ezra

_______________________________________________
Rails mailing list
Rails@lists.rubyonrails.org
http://lists.rubyonrails.org/mailman/listinfo/rails

Daniel Higginbotham

2006-Apr-16 09:42 UTC

head link

[Rails] variable variables?

One difficulty I found with Hash#to_sql was that if values in the hash were
empty you could end up with something like "seller_id = 3 AND AND views
45"
>From what I understand, though, part of the Ruby Way is to have many littlemethod that do one thing, so I should make method that strips out all empty
values first and pass the result to one of the new Hash methods.

I didn''t think about that until just now, though. In the mean time I
made
the following, which hopefully someone will find useful:

  def conditions_from_hash(some_hash)
    condition = ''''
    some_hash.each_pair {|key, value|
      if value.empty?
        next
      elsif (value.class == Hash) && value.values.inject{|total,
current| \
total+current}.empty?
        next
      elsif (value.class == Array)
        if value.inject{|total, current| total+current}.empty?
          next
        elsif /(.*)_ids$/.match(key)
          condition << "#{key[0...-4].pluralize}.`id` IN("
<< \
value.join('','') << ") AND "
        end
      elsif value[:from] || value[:to]
        condition << "#{key} >= #{value[:from]} AND " unless
\
value[:from].empty?
        condition << "#{key} <= #{value[:to]} AND " unless
value[:to].empty?
      else
        condition << "#{key} LIKE ''%#{value}%'' AND
"
      end
    }
    condition[0..-5].to_s
  end

It''s pretty much particular to what I''m trying to do, so it
doesn''t have
niceties like a "param" argument. What I''m trying to do is
perform a search
based on input which includes a range (<input
name="search[price][from]">
and <input search[price][to]) and a bunch of category checkboxes
(<checkbox
name="genre_ids[]">) . I wanted to keep the form of the code
general enough
to allow me to use it for other controllers in the site with the same needs.

Daniel

-----Original Message-----
From: rails-bounces@lists.rubyonrails.org
[mailto:rails-bounces@lists.rubyonrails.org] On Behalf Of Ezra Zygmuntowicz
Sent: Saturday, April 15, 2006 5:28 PM
To: rails@lists.rubyonrails.org
Subject: Re: [Rails] variable variables?


On Apr 15, 2006, at 8:17 PM, Daniel Higginbotham wrote:
> Hi everyone,
>
> Does Ruby support variable variables like PHP
> (http://www.php.net/manual/en/language.variables.variable.php)? Or  
> do I have
> to use eval, like
>
> some_hash.each_pair{|key, pair|
> 	eval "#{key} = #{value}"
> }
>
> Or is there some other way?
>
> I''m actually trying to figure this out in order to use ez_where to
> create
> its conditions from a hash, so if this isn''t even necessary could
> someone
> let me know?
>
> Thanks,
> Daniel
Daniel-

	There is already support for hash.to_sql and other niceties included

in ez_where. Like so:

class Hash #:nodoc:
   def to_sql(param = ''AND'')
     map { |key,value| key.to_s+'' = ''+ActiveRecord::Base.send 
(:sanitize, value) }.join('' ''+param+'' '')
   end

   def to_conditions(param = ''AND'')
     [map { |k, v| k.to_s+'' = ?'' }.join(''
''+param+'' ''), *values]
   end

   alias :to_sql_conditions :to_conditions
   def to_named_conditions(param = ''AND'')
     [map { |k, v| k.to_s+'' = :''+k }.join(''
''+param+'' ''),
self.symbolize_keys]
   end

end

Look in lib/hash.rb for this. Also the best way to see what that  
plugin is capable of is looking at the test suite. The  
ez_where_tests.rb file in the plugin is 700 lines long and exercises  
all the capabilities of the plugin. So you can see many many sample  
codes using the plugin in that tests file. Its the most complete  
documentation on it right now ;)

Cheers-
-Ezra

_______________________________________________
Rails mailing list
Rails@lists.rubyonrails.org
http://lists.rubyonrails.org/mailman/listinfo/rails

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