CODEWITHSUNDEEP
ruby-on-railsruby
Ringo Blancke
Ringo Blancke

Reputation: 2444

Ruby sorting issue

I'm trying to sort the array @users by the number of posts they have. Here's what I have in my controller:

@users = User.includes([:posts]).where("user_type = ?", "A")        
@users.sort {|a,b| (a.posts.size <=> b.posts.size)}

Here's what I have in my view:

<% @users.each do |user| %>
  <%= user.name %>: <%= user.posts.size %>
  <br>
<% end %>

My list of users is pretty random and is not properly sorted. If I'm not mistaken, the <=> operator is what I want to use. I want to return 1 if a has more posts than b, -1 if b has more posts than a and 0 if a and b have the same number of posts.

Upvotes: 0

Views: 58

Answers (3)

the Tin Man
the Tin Man

Reputation: 160553

Two things I see:

Instead of using sort, use sort_by when you have to dig into an object. It shouldn't be a big speed up for the short method chain you're using, but it can add up:

@users.sort_by! {|a| a.posts.size }

If you're retrieving your data from the database, instead of sorting in Ruby, use order or order_by, depending on which is supported, to have the DBM sort the data in the order you want. DBMs are optimized for sorting and can do it extremely fast.

Upvotes: 0

Logan Serman
Logan Serman

Reputation: 29860

You are using sort instead of sort!. sort! will sort @users in place.

Upvotes: 2

iltempo
iltempo

Reputation: 16012

It's just the missing bang.

@users.sort! {|a,b| (a.posts.size <=> b.posts.size)}

Upvotes: 4

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