How do I remove leading whitespace chars from Ruby HEREDOC?

Question

I\'m having a problem with a Ruby heredoc i\'m trying to make. It\'s returning the leading whitespace from each line even though i\'m including the - operator, which is supp

Answer 1

Some other answers find the indentation level of the least indented line, and delete that from all lines, but considering the nature of indentation in programming (that the first line is the least indented), I think you should look for the indentation level of the first line.

class String
  def unindent; gsub(/^#{match(/^\s+/)}/, "") end
end

Answer 2

Like the original poster, I too discovered the <<-HEREDOC syntax and was pretty damn disappointed that it didn't behave as I thought it should behave.

But instead of littering my code with gsub-s I extended the String class:

class String
  # Removes beginning-whitespace from each line of a string.
  # But only as many whitespace as the first line has.
  #
  # Ment to be used with heredoc strings like so:
  #
  # text = <<-EOS.unindent
  #   This line has no indentation
  #     This line has 2 spaces of indentation
  #   This line is also not indented
  # EOS
  #
  def unindent
    lines = []
    each_line {|ln| lines << ln }

    first_line_ws = lines[0].match(/^\s+/)[0]
    re = Regexp.new('^\s{0,' + first_line_ws.length.to_s + '}')

    lines.collect {|line| line.sub(re, "") }.join
  end
end

Answer 3

I collect answers and got this:

class Match < ActiveRecord::Base
  has_one :invitation
  scope :upcoming, -> do
    joins(:invitation)
    .where(<<-SQL_QUERY.strip_heredoc, Date.current, Date.current).order('invitations.date ASC')
      CASE WHEN invitations.autogenerated_for_round IS NULL THEN invitations.date >= ?
      ELSE (invitations.round_end_time >= ? AND match_plays.winner_id IS NULL) END
    SQL_QUERY
  end
end

It generates excellent SQL and do not go out of AR scopes.

Answer 4

Not much to do that I know of I'm afraid. I usually do:

def distinct_count
    <<-EOF.gsub /^\s+/, ""
        \tSELECT
        \t CAST('#{name}' AS VARCHAR(30)) as COLUMN_NAME
        \t,COUNT(DISTINCT #{name}) AS DISTINCT_COUNT
        \tFROM #{table.call}
    EOF
end

That works but is a bit of a hack.

EDIT: Taking inspiration from Rene Saarsoo below, I'd suggest something like this instead:

class String
  def unindent 
    gsub(/^#{scan(/^\s*/).min_by{|l|l.length}}/, "")
  end
end

def distinct_count
    <<-EOF.unindent
        \tSELECT
        \t CAST('#{name}' AS VARCHAR(30)) as COLUMN_NAME
        \t,COUNT(DISTINCT #{name}) AS DISTINCT_COUNT
        \tFROM #{table.call}
    EOF
end

This version should handle when the first line is not the one farthest to the left too.

Answer 5

Note: As @radiospiel pointed out, String#squish is only available in the ActiveSupport context.

---

I believe ruby's String#squish is closer to what you're really looking for:

Here is how I would handle your example:

def distinct_count
  <<-SQL.squish
    SELECT
      CAST('#{name}' AS VARCHAR(30)) as COLUMN_NAME,
      COUNT(DISTINCT #{name}) AS DISTINCT_COUNT
      FROM #{table.call}
  SQL
end