sql - How to Group by Date on Postgres via a Rails Model -


i'm using postgres ruby on rails , query posts table in away returns posts grouped day created_at, each group in chronological order.

a perfect example of goal blog that's index lists posts date.

the pseudo-code object structure expect similar this:

posts_grouped_by_date = {   "1/2/2014" => [post1, post2, post3],   "1/15/2014" => [post5, post6,post7],   etc.. }

my table called posts , looks this:

 id |                               title                               |         created_at ----+-------------------------------------------------------------------+----------------------------  13 | eaque hic tenetur @ quam quibusdam eveniet veritatis.            | 2014-08-18 02:40:31.329665   9 | thing want say.                                     | 2014-08-18 02:40:31.329665  16 | est sunt cumque rerum nam nobis consequuntur aut.                 | 2014-08-19 02:58:26.817936  18 | fuga assumenda facilis aut mollitia eum soluta.                   | 2014-08-19 02:58:26.837839   8 | thing want say.                                     | 2014-08-18 02:40:31.329665  12 | laudantium dolores odit sed veritatis in et vel deserunt.         | 2014-08-18 02:40:31.329665  10 | thing want say.                                     | 2014-08-18 02:40:31.329665  20 | rem laboriosam ipsam sunt maxime quia adipisci et voluptatem.     | 2014-08-19 02:58:26.837839  19 | laudantium sit explicabo et quia eligendi ipsam.                  | 2014-08-19 02:58:26.837839  21 | repellat qui eos dolorem.                                         | 2014-08-19 02:58:26.837839   6 | thing want say.                                     | 2014-08-18 02:40:31.329665  17 | error voluptatem architecto distinctio impedit iste dolores enim. | 2014-08-19 02:58:26.829968  15 | vero modi voluptate deleniti labore quis est.                     | 2014-08-19 02:58:26.808126  14 | et neque porro qui animi facilis numquam.                         | 2014-08-19 02:58:26.800474

how using activerecord or arel syntax? explanation behind code helpful too. i'm using learning/practice rather looking copy/paste.

i think want this:

post.order(:created_at).group_by {|p| p.created_at.to_date}

1 - post.order(:created_at) orders posts created_at attribute in ascending order.

2 - then, once have posts ordered group them using code in block. since don't want timestamp included in grouping (each second have different record, what's point?), convert timestamp date.


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