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POGet the Next/Previous record in ActiveRecord on Ruby on Rails
 

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  1. POGet the Next/Previous record in ActiveRecord on Ruby on Rails
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    <p>I am trying to get the next/previous record by ActiveRecord. The records should be retrieved <strong>according to the order by 'updated_at'</strong> column.</p> <p>The name of the Model is 'Youtube'. And as the following console, this code couldn't get the right record and I guess the idea of my code seems bad because <strong>updated_at is not always unique</strong> so some records <strong>might have the same time stamp</strong>.</p> <p>How do you get the next/previous record in a right way?</p> <p>Console said below.</p> <pre><code>[57] pry(main)&gt; Youtube.find(1000) Youtube Load (0.5ms) SELECT "youtubes".* FROM "youtubes" WHERE "youtubes"."id" = $1 ORDER BY updated_at DESC LIMIT 1 [["id", 1000]] =&gt; #&lt;Youtube id: 1000, author_id: 2, category_label: nil, generated_by: 1, title: "Is Kenya Mall Shooting Over? Were Americans Among A...", video_id: "4T1szQIQcNI", created_at: "2013-09-30 18:31:21", updated_at: "2013-10-27 02:19:56", subtitles: nil&gt; [58] pry(main)&gt; Youtube.find(1000).next Youtube Load (0.6ms) SELECT "youtubes".* FROM "youtubes" WHERE "youtubes"."id" = $1 ORDER BY updated_at DESC LIMIT 1 [["id", 1000]] Sun, 27 Oct 2013 02:19:56 UTC +00:00 Youtube Load (256.6ms) SELECT "youtubes".* FROM "youtubes" WHERE (updated_at &gt; '2013-10-27 02:19:56.593969') ORDER BY updated_at DESC LIMIT 1 =&gt; #&lt;Youtube id: 67003, author_id: 75, category_label: nil, generated_by: 1, title: "Jewelry Photography : Lenses for Jewelry Photograph...", video_id: "NqA7OZL4tzw", created_at: "2013-10-09 17:18:53", updated_at: "2013-10-28 02:17:33", subtitles: nil&gt; [59] pry(main)&gt; Youtube.find(1000).previous Youtube Load (0.6ms) SELECT "youtubes".* FROM "youtubes" WHERE "youtubes"."id" = $1 ORDER BY updated_at DESC LIMIT 1 [["id", 1000]] Sun, 27 Oct 2013 02:19:56 UTC +00:00 Youtube Load (56.3ms) SELECT "youtubes".* FROM "youtubes" WHERE (updated_at &lt; '2013-10-27 02:19:56.593969') ORDER BY updated_at DESC LIMIT 1 =&gt; #&lt;Youtube id: 999, author_id: 8, category_label: nil, generated_by: 1, title: "Authors@Google: Richard Moore, Ned Boulting, and Da...", video_id: "4SCzfuJAyJw", created_at: "2013-09-30 18:31:21", updated_at: "2013-10-27 02:19:55", subtitles: nil&gt; </code></pre> <p>Youtube has the following default_scope. Although this might be changed according to some situation, but I hope this code would be kept to keep the existing behaviour.</p> <pre><code> default_scope order('updated_at DESC') </code></pre> <p>My trial code for Youtube Model is below.</p> <pre><code> scope :next, lambda{|updated_at| where("updated_at &gt; ?", updated_at).order("updated_at DESC")} scope :previous, lambda {|updated_at| where("updated_at &lt; ?", updated_at).order("updated_at DESC")} </code></pre> <p>...</p> <pre><code> def next self.class.next(updated_at).first end def previous self.class.previous(updated_at).first end </code></pre>
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    1. COSee here: http://stackoverflow.com/questions/7394088/rails-get-next-previous-record
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      1. USDamien Roche
    2. CODamien, I checked http://stackoverflow.com/questions/7394088/rails-get-next-previous-record, but it was not the right solution for this case as explained above.
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