Rails adds a limit of fetching 10 records when using pretty print

· 4 min read

ActiveRecord::Relation#pretty_print is a method that pretty prints an ActiveRecord::Relation object.

Example

Without pretty print:

irb(main):002:0> Post.limit(2)
Post Load (2.7ms)  SELECT  "posts".* FROM "posts" ORDER BY "posts"."id" ASC LIMIT $1  [["LIMIT", 2]]
=> #<ActiveRecord::Relation [#<Post id: 1, title: "First Post", body: "First Post Body", created_at: "2022-01-18 07:30:36", updated_at: "2022-01-18 07:30:36">, #<Post id: 2, title: "Second Post", body: "Second Post Body", created_at: "2022-01-18 07:30:36", updated_at: "2022-01-18 07:30:36">]

With pretty print:

irb(main):003:0> pp Post.limit(2)
Post Load (0.6ms)  SELECT  "posts".* FROM "posts" ORDER BY "posts"."id" ASC LIMIT $1  [["LIMIT", 2]]
[#<Post:0x00005654ccd32d28
  id: 1,
  title: "First Post",
  body: "First Post Body",
  created_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00,
  updated_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00>,
 #<Post:0x00005654ccd32b98
  id: 2,
  title: "Second Post",
  body: "Second Post Body",
  created_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00,
  updated_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00>]
=> #<ActiveRecord::Relation [#<Post id: 1, title: "First Post", body: "First Post Body", created_at: "2022-01-18 07:30:36", updated_at: "2022-01-18 07:30:36">, #<Post id: 2, title: "Second Post", body: "Second Post Body", created_at: "2022-01-18 07:30:36", updated_at: "2022-01-18 07:30:36">]

Before

The method works great, but since it loads all the records of the relation, it can be very slow for bigger relations.

Example

irb(main):004:0> pp Post.all # Loads all the records

Rails 7

Rails 7 adds a limit of fetching upto 11 records when using pretty print much like ActiveRecord::Base#inspect if the records aren’t already loaded.

Note: The 11th record is not shown. It is only loaded to determine whether there are more records to show. An ellipsis (…) is shown instead of the 11th record.

Example

irb(main):005:0> pp Post.all
# Loads only 10 records and adds an ellipsis at the end if there are more records
Post Load (0.6ms)  SELECT  "posts".* FROM "posts" `/*` loading for pp `*/` ORDER BY "posts"."id" ASC LIMIT $1  [["LIMIT", 11]]
[#<Post:0x00007fed44c7abd0
  id: 1,
  title: "First Post",
  body: "First Post Body",
  created_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00,
  updated_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00>,
 #<Post:0x00007fed44c7aa68
  id: 2,
  title: "Second Post",
  body: "Second Post Body",
  created_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00,
  updated_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00>,
  #<Post:0x00007fed44c7a608
  id: 3,
  title: "Second Post",
  body: "Second Post Body",
  created_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00,
  updated_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00>,
  #<Post:0x00007fed44c7a478
  id: 4,
  title: "Fourth Post",
  body: "Fourth Post Body",
  created_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00,
  updated_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00>,
  #<Post:0x00007fed44c79ac8
  id: 5,
  title: "Fifth Post",
  body: "Fifth Post Body",
  created_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00,
  updated_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00>,
  #<Post:0x00007fed44c79398
  id: 6,
  title: "Sixth Post",
  body: "Sixth Post Body",
  created_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00,
  updated_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00>,
  #<Post:0x00007fed44c784c0
  id: 7,
  title: "Seventh Post",
  body: "Seventh Post Body",
  created_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00,
  updated_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00>,
  #<Post:0x00007fed44c73ec0
  id: 8,
  title: "Eighth Post",
  body: "Eighth Post Body",
  created_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00,
  updated_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00>,
  #<Post:0x00007fed44c73858
  id: 9,
  title: "Ninth Post",
  body: "Ninth Post Body",
  created_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00,
  updated_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00>,
  #<Post:0x00007fed44c73538
  id: 10,
  title: "Tenth Post",
  body: "Tenth Post Body",
  created_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00,
  updated_at: Tue, 18 Jan 2022 07:30:36 UTC +00:00>,
  "..."]
Prateek Choudhary
Prateek Choudhary
Technology Leader

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