Class: ActiveRecord::Result

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Instance Chain: self, `::Enumerable`, `::ActiveSupport::EnumerableCoreExt::Constants`
Inherits:	Object
Defined in:	activerecord/lib/active_record/result.rb

Overview

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

Constant Summary

EMPTY = private
# File 'activerecord/lib/active_record/result.rb', line 195
```
new([].freeze, [].freeze, {}.freeze).freeze
```
EMPTY_ASYNC = private
# File 'activerecord/lib/active_record/result.rb', line 198
```
FutureResult.wrap(EMPTY).freeze
```

Class Method Summary

.new(columns, rows, column_types = {}) ⇒ Result constructor
.empty(async: false) Internal use only

Instance Attribute Summary

#column_types readonly
#columns readonly
#empty? ⇒ Boolean readonly

Returns true if there are no records, otherwise false.
#rows readonly

`::Enumerable` - Included

#many?

Returns true if the enumerable has more than 1 element.

Instance Method Summary

#[](idx)
#each(&block)

Calls the given block once for each element in row collection, passing row as parameter.
#includes_column?(name) ⇒ Boolean

Returns true if this result set includes the column named name
#initialize_copy(other)
#last(n = nil)

Returns the last record from the rows collection.
#length

Returns the number of elements in the rows array.
#to_a

Alias for #to_ary.
#to_ary (also: #to_a)

Returns an array of hashes representing each row record.
#column_type(name, index, type_overrides) private
#hash_rows private
#cancel Internal use only
#cast_values(type_overrides = {}) Internal use only
#freeze Internal use only
#result Internal use only

`::Enumerable` - Included

#compact_blank	Returns a new `::Array` without the blank items.
#exclude?	The negative of the `Enumerable#include?`.
#excluding	Returns a copy of the enumerable excluding the specified elements.
#in_order_of	Returns a new `::Array` where the order has been set to that provided in the `series`, based on the `key` of the objects in the original enumerable.
#including	Returns a new array that includes the passed elements.
#index_by	Convert an enumerable to a hash, using the block result as the key and the element as the value.
#index_with	Convert an enumerable to a hash, using the element as the key and the block result as the value.
#maximum	Calculates the maximum from the extracted elements.
#minimum	Calculates the minimum from the extracted elements.
#pick	Extract the given key from the first element in the enumerable.
#pluck	Extract the given key from each element in the enumerable.
#sole	Returns the sole item in the enumerable.
#without	Alias for Enumerable#excluding.
#as_json

`::ActiveSupport::EnumerableCoreExt::Constants` - Included

#const_missing

Constructor Details

.new(columns, rows, column_types = {}) ⇒ `Result`

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 49


def initialize(columns, rows, column_types = {})
  @columns      = columns
  @rows         = rows
  @hash_rows    = nil
  @column_types = column_types
end

Class Method Details

.empty(async: false)

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 41


def self.empty(async: false) # :nodoc:
  if async
    EMPTY_ASYNC
  else
    EMPTY
  end
end

Instance Attribute Details

#column_types (readonly)

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 39


attr_reader :columns, :rows, :column_types

#columns (readonly)

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 39


attr_reader :columns, :rows, :column_types

#empty? ⇒ `Boolean` (readonly)

Returns true if there are no records, otherwise false.

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 79


def empty?
  rows.empty?
end

#rows (readonly)

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 39


attr_reader :columns, :rows, :column_types

Instance Method Details

#[](idx)

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 90


def [](idx)
  hash_rows[idx]
end

#cancel

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 103


def cancel # :nodoc:
  self
end

#cast_values(type_overrides = {})

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 107


def cast_values(type_overrides = {}) # :nodoc:
  if columns.one?
    # Separated to avoid allocating an array per row

    type = if type_overrides.is_a?(Array)
      type_overrides.first
    else
      column_type(columns.first, 0, type_overrides)
    end

    rows.map do |(value)|
      type.deserialize(value)
    end
  else
    types = if type_overrides.is_a?(Array)
      type_overrides
    else
      columns.map.with_index { |name, i| column_type(name, i, type_overrides) }
    end

    rows.map do |values|
      Array.new(values.size) { |i| types[i].deserialize(values[i]) }
    end
  end
end

#column_type(name, index, type_overrides) (private)

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 146


def column_type(name, index, type_overrides)
  type_overrides.fetch(name) do
    column_types.fetch(index) do
      column_types.fetch(name, Type.default_value)
    end
  end
end

#each(&block)

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

Returns an Enumerator if no block is given.

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 70


def each(&block)
  if block_given?
    hash_rows.each(&block)
  else
    hash_rows.to_enum { @rows.size }
  end
end

#freeze

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 140


def freeze # :nodoc:
  hash_rows.freeze
  super
end

#hash_rows (private)

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 154


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

#includes_column?(name) ⇒ `Boolean`

Returns true if this result set includes the column named name

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 57


def includes_column?(name)
  @columns.include? name
end

#initialize_copy(other)

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 133


def initialize_copy(other)
  @columns      = columns.dup
  @rows         = rows.dup
  @column_types = column_types.dup
  @hash_rows    = nil
end

#last(n = nil)

Returns the last record from the rows collection.

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 95


def last(n = nil)
  n ? hash_rows.last(n) : hash_rows.last
end

#length

Returns the number of elements in the rows array.

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 62


def length
  @rows.length
end

#result

This method is for internal use only.

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 99


def result # :nodoc:
  self
end

#to_a

Alias for #to_ary.

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 88


alias :to_a :to_ary

#to_ary Also known as: #to_a

Returns an array of hashes representing each row record.

[ GitHub ]

# File 'activerecord/lib/active_record/result.rb', line 84


def to_ary
  hash_rows
end

Class: ActiveRecord::Result

Overview

Constant Summary

Class Method Summary

Instance Attribute Summary

::Enumerable - Included

Instance Method Summary

::Enumerable - Included

::ActiveSupport::EnumerableCoreExt::Constants - Included

Constructor Details

.new(columns, rows, column_types = {}) ⇒ Result

Class Method Details

.empty(async: false)

Instance Attribute Details

#column_types (readonly)

#columns (readonly)

#empty? ⇒ Boolean (readonly)

#rows (readonly)

Instance Method Details

#[](idx)

#cancel

#cast_values(type_overrides = {})

#column_type(name, index, type_overrides) (private)

#each(&block)

#freeze

#hash_rows (private)

#includes_column?(name) ⇒ Boolean

#initialize_copy(other)

#last(n = nil)

#length

#result

#to_a

#to_ary Also known as: #to_a

`::Enumerable` - Included

`::Enumerable` - Included

`::ActiveSupport::EnumerableCoreExt::Constants` - Included

.new(columns, rows, column_types = {}) ⇒ `Result`

#empty? ⇒ `Boolean` (readonly)

#includes_column?(name) ⇒ `Boolean`