The project is in a healthy, maintained state
This is an ActiveRecord integration for the SQL prettifier gem niceql.


~> 0.1
~> 5.0
~> 1
>= 12.3.3
~> 0.2


 Project Readme


This is an ActiveRecord integration for a niceql gem ( niceql is a small, nice, simple and zero dependency solution for the SQL prettifying in ruby ).

This gem started as a code extraction from niceql version 0.4.x.

It has versioning aligned to the ActiveRecord versions, niceql prior to 0.5 version had hardcoded logic branches based on ActiveRecord versioning.

That is hard to maintain and hard to test, and also coupling with AR is breaking the original idea of the niceql to be a dependentless solution, so now the niceql is a completely railsfree gem yeay! ( It still has some some checks related to AR implementations in the error prettifying methods. It will be completely decoupled in the future )

Any reasonable suggestions are welcome.

Please pay attention: until issue alekseyl/niceql#16 is resolved any UPDATE or INSERT request might corrupt your data, don't use on production!


SQL prettifier:

alt text

PG errors prettifier

before: alt text

after: alt text


rails_sql_prettifier, has several version compatible with different active_record versions, so pay attention to the right versioning if whenever you specify versions manually.

Add this line to your application's Gemfile:

gem 'rails_sql_prettifier', '~> X.X.X'

And then execute:

$ bundle
# if you are using rails, you may want to install niceql config:
rails g niceql:install 

Or install it yourself as:

$ gem install niceql


Niceql.configure do |c|
  # Setting pg_adapter_with_nicesql to true will APPLY formatting SQL queries
  # before execution. Formatted SQL will lead to much better SQL-query debugging and much more clearer error messages 
  # if you are using Postgresql as a data source. 
  # BUT even though is resolved, 
  # there could be other potentially uncovered bugs so its better not to
  # adjust pg_adapter in production, currently there is an additional blocker for that module ProtectedEnv
  # its will not allow patching PGAdapter for other than test/development envs 
  # If you need to debug SQL queries in production use exec_niceql
  # default value for pg_adapter_with_nicesql: false
  # uncomment next string to enable in development
  # c.pg_adapter_with_nicesql = Rails.env.development?
  # uncomment next string if you want to log prettified SQL inside ActiveRecord logging. 
  # default: false
  # c.prettify_active_record_log_output = true
  # Error prettifying is also configurable
  # default: defined? ::ActiveRecord::Base && ActiveRecord::Base.configurations[Rails.env]['adapter'] == 'postgresql'
  # c.prettify_pg_errors = defined? ::ActiveRecord::Base && ActiveRecord::Base.configurations[Rails.env]['adapter'] == 'postgresql'
  # spaces count for one indentation, default is 2
  c.indentation_base = 2
  # setting open_bracket_is_newliner to true will start opening brackets '(' with nested subqueries from new line 
  # i.e. SELECT * FROM ( SELECT * FROM tags ) tags; will transform to: 
  # SELECT * 
  # FROM 
  # ( 
 #    SELECT * FROM tags 
 #  ) tags;
 # when open_bracket_is_newliner is false: 
  # SELECT * 
  # FROM ( 
 #   SELECT * FROM tags 
 # ) tags; 
 # default: false
  c.open_bracket_is_newliner = false


  # puts colorized and formatted corresponding SQL query
  # only formatting without colorization, you can run output of to_niceql as a SQL query in connection.execute  
  # will run prettified sql and hence will properly prettify PG errors if scope runs with any 

Raw usage of niceql

    puts Niceql::Prettifier.prettify_sql("SELECT * FROM ( VALUES(1), (2) ) AS tmp")
    #=>  SELECT * 
    #=>  FROM ( VALUES(1), (2) ) AS tmp
    puts Niceql::Prettifier.prettify_multiple("SELECT * FROM ( VALUES(1), (2) ) AS tmp; SELECT * FROM table")
    #=>  SELECT * 
    #=>  FROM ( VALUES(1), (2) ) AS tmp;
    #=>  SELECT * 
    #=>  FROM table

   puts Niceql::Prettifier.prettify_pg_err( pg_err_output, sql_query )
   # to get real nice result you should execute prettified version (i.e. execute( prettified_sql ) !) of query on your DB! 
   # otherwise you will not get such a nice output
    raw_sql = <<~SQL
     SELECT err 
     FROM ( VALUES(1), (2) )
     ORDER BY 1

    puts Niceql::Prettifier.prettify_pg_err(<<~ERR, raw_sql )
        ERROR:  VALUES in FROM must have an alias
        LINE 2:  FROM ( VALUES(1), (2) )
        HINT:  For example, FROM (VALUES ...) [AS] foo.
    # ERROR:  VALUES in FROM must have an alias
    # LINE 2:  FROM ( VALUES(1), (2) )
    #               ^
    #     HINT:  For example, FROM (VALUES ...) [AS] foo.
    #     SELECT err
    #     FROM ( VALUES(1), (2) )
    #          ^
    #     ORDER BY 1

Customizing colors

If your console support more colors or different schemes, or if you prefer different colorization, then you can override ColorizeString methods. Current colors were selected with dark and white console themes in mind, so a niceql colorization works good for dark, and good enough for white.


docker-compose up


Bug reports and pull requests are welcome on GitHub at


The gem is available as open source under the terms of the MIT License.