class ActiveRecord::Result

This class encapsulates a result returned from calling #exec_query on any database connection adapter. For example:

result = ActiveRecord::Base.connection.exec_query('SELECT id, title, body FROM posts')
result # => #<ActiveRecord::Result:0xdeadbeef>

# Get the column names of the result:
result.columns
# => ["id", "title", "body"]

# Get the record values of the result:
result.rows
# => [[1, "title_1", "body_1"],
      [2, "title_2", "body_2"],
      ...
     ]

# Get an array of hashes representing the result (column => value):
result.to_a
# => [{"id" => 1, "title" => "title_1", "body" => "body_1"},
      {"id" => 2, "title" => "title_2", "body" => "body_2"},
      ...
     ]

# ActiveRecord::Result also includes Enumerable.
result.each do |row|
  puts row['title'] + " " + row['body']
end

Attributes

column_types[R]
columns[R]
rows[R]

Public Class Methods

new(columns, rows, column_types = {}) click to toggle source
# File lib/active_record/result.rb, line 39
def initialize(columns, rows, column_types = {})
  @columns      = columns
  @rows         = rows
  @hash_rows    = nil
  @column_types = column_types
end

Public Instance Methods

[](idx) click to toggle source
# File lib/active_record/result.rb, line 85
def [](idx)
  hash_rows[idx]
end
each() { |row| ... } click to toggle source

Calls the given block once for each element in row collection, passing row as parameter.

Returns an Enumerator if no block is given.

# File lib/active_record/result.rb, line 60
def each
  if block_given?
    hash_rows.each { |row| yield row }
  else
    hash_rows.to_enum { @rows.size }
  end
end
empty?() click to toggle source

Returns true if there are no records, otherwise false.

# File lib/active_record/result.rb, line 74
def empty?
  rows.empty?
end
includes_column?(name) click to toggle source

Returns true if this result set includes the column named name

# File lib/active_record/result.rb, line 47
def includes_column?(name)
  @columns.include? name
end
initialize_copy(other) click to toggle source
# File lib/active_record/result.rb, line 120
def initialize_copy(other)
  @columns      = columns.dup
  @rows         = rows.dup
  @column_types = column_types.dup
  @hash_rows    = nil
end
last(n = nil) click to toggle source

Returns the last record from the rows collection.

# File lib/active_record/result.rb, line 90
def last(n = nil)
  n ? hash_rows.last(n) : hash_rows.last
end
length() click to toggle source

Returns the number of elements in the rows array.

# File lib/active_record/result.rb, line 52
def length
  @rows.length
end
to_a()
Alias for: to_ary
to_ary() click to toggle source

Returns an array of hashes representing each row record.

# File lib/active_record/result.rb, line 79
def to_ary
  hash_rows
end
Also aliased as: to_a

Private Instance Methods

column_type(name, type_overrides = {}) click to toggle source
# File lib/active_record/result.rb, line 128
def column_type(name, type_overrides = {})
  type_overrides.fetch(name) do
    column_types.fetch(name, Type.default_value)
  end
end
hash_rows() click to toggle source
# File lib/active_record/result.rb, line 134
def hash_rows
  @hash_rows ||=
    begin
      # We freeze the strings to prevent them getting duped when
      # used as keys in ActiveRecord::Base's @attributes hash
      columns = @columns.map(&:-@)
      length  = columns.length
      template = nil

      @rows.map { |row|
        if template
          # We use transform_values to build subsequent rows from the
          # hash of the first row. This is faster because we avoid any
          # reallocs and in Ruby 2.7+ avoid hashing entirely.
          index = -1
          template.transform_values do
            row[index += 1]
          end
        else
          # In the past we used Hash[columns.zip(row)]
          #  though elegant, the verbose way is much more efficient
          #  both time and memory wise cause it avoids a big array allocation
          #  this method is called a lot and needs to be micro optimised
          hash = {}

          index = 0
          while index < length
            hash[columns[index]] = row[index]
            index += 1
          end

          # It's possible to select the same column twice, in which case
          # we can't use a template
          template = hash if hash.length == length

          hash
        end
      }
    end
end