Class: SeedFu::Writer

Inherits:
Object
  • Object
show all
Defined in:
lib/seed-fu/writer.rb

Overview

Writer is used to programmatically generated seed files. For example, you might want to write a script which converts data in a CSV file to a valid Seed Fu seed file, which can then be imported.

Examples:

Basic usage

SeedFu::Writer.write('path/to/file.rb', :class_name => 'Person', :constraints => [:first_name, :last_name]) do |writer|
  writer.add(:first_name => 'Jon',   :last_name => 'Smith',    :age => 21)
  writer.add(:first_name => 'Emily', :last_name => 'McDonald', :age => 24)
end

# Writes the following to the file:
#
# Person.seed(:first_name, :last_name,
#   {:first_name=>"Jon", :last_name=>"Smith", :age=>21},
#   {:first_name=>"Emily", :last_name=>"McDonald", :age=>24}
# )

Constant Summary collapse

@@default_options = 
{
  :chunk_size  => 100,
  :constraints => [:id],
  :seed_type   => :seed
}

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Writer

Returns a new instance of Writer.

Parameters:

  • options (Hash) (defaults to: {})

Options Hash (options):

  • :class_name (String) —

    Required The name of the Active Record model to generate seeds for

  • :chunk_size (Fixnum) — default: 100 —

    The number of seeds to write before generating a ‘# BREAK EVAL` line. (Chunking reduces memory usage when loading seeds.)

  • :seed_type (:seed, :seed_once) — default: :seed —

    The method to use when generating seeds. See ActiveRecordExtension for details.

  • :constraints (Array<Symbol>) — default: [:id] —

    The constraining attributes for the seeds

Raises:

  • (ArgumentError) 


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# File 'lib/seed-fu/writer.rb', line 34

def initialize(options = {})
  @options = self.class.default_options.merge(options)
  raise ArgumentError, "missing option :class_name" unless @options[:class_name]
end

Class Method Details

.write(io_or_filename, options = {}, &block) ⇒ Object

Creates a new instance of SeedFu::Writer with the ‘options`, and then calls #write with the `io_or_filename` and `block`



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# File 'lib/seed-fu/writer.rb', line 41

def self.write(io_or_filename, options = {}, &block)
  new(options).write(io_or_filename, &block)
end

Instance Method Details

#<<(seed) ⇒ Object Also known as: add

Add a seed. Must be called within a block passed to #write.

Parameters:

  • seed (Hash) —

    The attributes for the seed



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# File 'lib/seed-fu/writer.rb', line 67

def <<(seed)
  raise "You must add seeds inside a SeedFu::Writer#write block" unless @io

  buffer = ''

  if chunk_this_seed?
    buffer << seed_footer
    buffer << "# BREAK EVAL\n"
    buffer << seed_header
  end

  buffer << ",\n"
  buffer << '  ' + seed.inspect

  @io.write(buffer)

  @count += 1
end

#write(io_or_filename) {|self| ... } ⇒ Object

Writes the necessary headers and footers, and yields to a block within which the actual seed data should be writting using the ‘#<<` method.

Parameters:

  • io_or_filename (IO) —

    The IO to which writes will be made. (If an ‘IO` is given, it is your responsibility to close it after writing.)

  • io_or_filename (String) —

    The filename of a file to make writes to. (Will be opened and closed automatically.)

Yields:

  • (self) —

    make calls to ‘#<<` within the block

Raises:

  • (ArgumentError) 


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# File 'lib/seed-fu/writer.rb', line 53

def write(io_or_filename, &block)
  raise ArgumentError, "missing block" unless block_given?

  if io_or_filename.respond_to?(:write)
    write_to_io(io_or_filename, &block)
  else
    File.open(io_or_filename, 'w') do |file|
      write_to_io(file, &block)
    end
  end
end