    &lt;% @images.each_with_index do |page, index| %&gt;
    
    &lt;% end %&gt;

The two answers are good.
And I also suggest you a similar method:

    &lt;% @images.each.with_index do |page, index| %&gt;
    &lt;% end %&gt;

You might not see the difference between this and the accepted answer. Let me direct your eyes to these method calls: `.each.with_index` see how it&#39;s `.each` and then `.with_index`.

Try [each_with_index][1].


  [1]: http://ruby-doc.org/core-1.8.7/classes/Enumerable.html#M001172

I have a field at a grid containing date/time and I need to know the difference between that and the current date/time. What could be the best way of doing so?

The dates are stored like `&quot;2011-02-07 15:13:06&quot;`.

How to subtract date/time in JavaScript?

Is it possible for the same exact Mongo ObjectId to be generated for a document in two different collections?  I realize that it&#39;s definitely very unlikely, but is it possible?  

Without getting too specific, the reason I ask is that with an application that I&#39;m working on we show public profiles of elected officials who we hope to convert into full fledged users of our site.  We have separate collections for users and the elected officials who aren&#39;t currently members of our site.  There are various other documents containing various pieces of data about the elected officials that all map back to the person using their elected official ObjectId.

After creating the account we still highlight the data that&#39;s associated to the elected official but they now also are a part of the users collection with a corresponding users ObjectId to map their profile to interactions with our application.

We had begun converting our application from MySql to Mongo a few months ago and while we&#39;re in transition we store the legacy MySql id for both of these data types and we&#39;re also starting to now store the elected official Mongo ObjectId in the users document to map back to the elected official data.

I was pondering just specifying the new user ObjectId as the previous elected official ObjectId to make things simpler but wanted to make sure that it wasn&#39;t possible to have a collision with any existing user ObjectId.

Thanks for your insight.

Edit:  Shortly after posting this question, I realized that my proposed solution wasn&#39;t a very good idea.  It would be better to just keep the current schema that we have in place and just link to the elected official &#39;_id&#39; in the users document.

Possibility of duplicate Mongo ObjectId&#39;s being generated in two different collections?

So I have this loop:

    &lt;% @images.each do |page| %&gt;

    &lt;% end %&gt;

How would I get the index of &quot;page&quot; inside of the loop?

Rails get index of &quot;each&quot; loop

So I have this loop:
<pre><code class="hljs language-ruby">&#x3C;% @images.each do |page| %>

&#x3C;% end %>
</code></pre>
How would I get the index of "page" inside of the loop?

Often I need to check if some value is blank and write that &quot;No data present&quot; like that:

    @user.address.blank? ? &quot;We don&#39;t know user&#39;s address&quot; : @user.address

And when we have got about 20-30 fields that we need to process this way it becomes ugly.

What I&#39;ve made is extended String class with `or` method

    class String
      def or(what)
        self.strip.blank? ? what : self
      end
    end

    @user.address.or(&quot;We don&#39;t know user&#39;s address&quot;)

Now it is looking better. But it is still raw and rough

How it would be better to solve my problem. Maybe it would be better to extend `ActiveSupport class` or use helper method or mixins or anything else. What ruby idealogy, your experience and best practices can tell to me.

If string is empty then return some default value

I have seen a lot usage of double colons in Rails before class names.

For example:

    require ::File.expand_path(&#39;../config/environment&#39;,  __FILE__)

I know what `Module::Class::Constant` means, but `::Class` ?

Double colons before class names in Ruby?

How can I get the current session id in rails 3?

I&#39;ve tried the following with no luck:

    session[:session_id]
    session[&#39;session_id&#39;]
    session[:id]
    session[&#39;id&#39;]
    session.id
    session.session_id

Finding the session id in rails 3

I tried using `gem install pg` but it doesn&#39;t seem to work.

`gem install pg` gives this error

    Temporarily enhancing PATH to include DevKit...
    Building native extensions.  This could take a while...
    ERROR:  Error installing pg:
            ERROR: Failed to build gem native extension.
    
    C:/Ruby/bin/ruby.exe extconf.rb
    checking for pg_config... no
    No pg_config... trying anyway. If building fails, please try again with
     --with-pg-config=/path/to/pg_config
    checking for libpq-fe.h... no
    Can&#39;t find the &#39;libpq-fe.h header
    *** extconf.rb failed ***
    Could not create Makefile due to some reason, probably lack of
    necessary libraries and/or headers.  Check the mkmf.log file for more
    details.  You may need configuration options.
    
    Provided configuration options:
            --with-opt-dir
            --without-opt-dir
            --with-opt-include
            --without-opt-include=${opt-dir}/include
            --with-opt-lib
            --without-opt-lib=${opt-dir}/lib
            --with-make-prog
            --without-make-prog
            --srcdir=.
            --curdir
            --ruby=C:/Ruby/bin/ruby
            --with-pg
            --without-pg
            --with-pg-dir
            --without-pg-dir
            --with-pg-include
            --without-pg-include=${pg-dir}/include
            --with-pg-lib
            --without-pg-lib=${pg-dir}/lib
            --with-pg-config
            --without-pg-config
            --with-pg_config
            --without-pg_config
    
    
    Gem files will remain installed in C:/Ruby/lib/ruby/gems/1.8/gems/pg-0.10.1 for
    inspection.
    Results logged to C:/Ruby/lib/ruby/gems/1.8/gems/pg-0.10.1/ext/gem_make.out



unable to install pg gem

I think I&#39;m trying to get the PHP equivalent of `print_r()` (print human-readable); at present the raw output is:

    ActiveRecord::Relation:0x10355d1c0

What should I do?

How do I print out the contents of an object in Rails for easy debugging?

Is it possible to change the default field separator from comma to to some other character, e.g `&#39;|&#39;` for exporting?

Changing field separator/delimiter in exported CSV using Ruby CSV

It&#39;s easy enough to read a CSV file into an array with Ruby but I can&#39;t find any good documentation on how to write an array into a CSV file. Can anyone tell me how to do this?

I&#39;m using Ruby 1.9.2 if that matters.

Content Type	Original Author	Original Content on Stackoverflow
Question	criticerz	View Question on Stackoverflow
Solution 1 - Ruby on-Rails	PreciousBodilyFluids	View Answer on Stackoverflow
Solution 2 - Ruby on-Rails	Tatsuro Baba	View Answer on Stackoverflow
Solution 3 - Ruby on-Rails	Brett Bender	View Answer on Stackoverflow

Rails get index of "each" loop

Ruby on-Rails Problem Overview

Ruby on-Rails Solutions

Solution 1 - Ruby on-Rails

Solution 2 - Ruby on-Rails

Solution 3 - Ruby on-Rails

Possibility of duplicate Mongo ObjectId's being generated in two different collections?

How to subtract date/time in JavaScript?

Attributions