Class: ActiveRecord::Result

Inherits:
Object
  • Object
show all
Includes:
Enumerable
Defined in:
lib/active_record/result.rb

Overview

Active Record Result

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

result = ActiveRecord::Base.lease_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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(columns, rows, column_types = nil) ⇒ Result

Returns a new instance of Result.



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

def initialize(columns, rows, column_types = nil)
  # We freeze the strings to prevent them getting duped when
  # used as keys in ActiveRecord::Base's @attributes hash
  @columns      = columns.each(&:-@).freeze
  @rows         = rows
  @hash_rows    = nil
  @column_types = column_types || EMPTY_HASH
  @column_indexes = nil
end

Instance Attribute Details

#column_types ⇒ Object (readonly)

Returns the value of attribute column_types.



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

def column_types
  @column_types
end

#columns ⇒ Object (readonly)

Returns the value of attribute columns.



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

def columns
  @columns
end

#rows ⇒ Object (readonly)

Returns the value of attribute rows.



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

def rows
  @rows
end

Class Method Details

.empty(async: false) ⇒ Object

:nodoc:



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

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

Instance Method Details

#[](idx) ⇒ Object 



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# File 'lib/active_record/result.rb', line 93

def [](idx)
  hash_rows[idx]
end

#cancel ⇒ Object

:nodoc:



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# File 'lib/active_record/result.rb', line 106

def cancel # :nodoc:
  self
end

#cast_values(type_overrides = {}) ⇒ Object

:nodoc:



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# File 'lib/active_record/result.rb', line 110

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_indexes ⇒ Object

:nodoc:



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# File 'lib/active_record/result.rb', line 148

def column_indexes # :nodoc:
  @column_indexes ||= begin
    index = 0
    hash = {}
    length  = columns.length
    while index < length
      hash[columns[index]] = index
      index += 1
    end
    hash
  end
end

#each(&block) ⇒ Object

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

Returns an Enumerator if no block is given.



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# File 'lib/active_record/result.rb', line 73

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

#empty? ⇒ Boolean

Returns true if there are no records, otherwise false.

Returns:

  • (Boolean) 


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# File 'lib/active_record/result.rb', line 82

def empty?
  rows.empty?
end

#freeze ⇒ Object

:nodoc:



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# File 'lib/active_record/result.rb', line 143

def freeze # :nodoc:
  hash_rows.freeze
  super
end

#includes_column?(name) ⇒ Boolean

Returns true if this result set includes the column named name

Returns:

  • (Boolean) 


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# File 'lib/active_record/result.rb', line 60

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

#initialize_copy(other) ⇒ Object 



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# File 'lib/active_record/result.rb', line 136

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

#last(n = nil) ⇒ Object

Returns the last record from the rows collection.



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# File 'lib/active_record/result.rb', line 98

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

#length ⇒ Object

Returns the number of elements in the rows array.



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# File 'lib/active_record/result.rb', line 65

def length
  @rows.length
end

#result ⇒ Object

:nodoc:



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# File 'lib/active_record/result.rb', line 102

def result # :nodoc:
  self
end

#to_ary ⇒ Object Also known as: to_a

Returns an array of hashes representing each row record.



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# File 'lib/active_record/result.rb', line 87

def to_ary
  hash_rows
end