Module: DbAgile::IO::CSV

Extended by:
TypeSafe
Defined in:
lib/dbagile/io/csv.rb

Class Method Summary collapse

Methods included from TypeSafe

from_typesafe_relation, from_typesafe_tuple, from_typesafe_xxx, to_typesafe_relation, to_typesafe_tuple, with_type_safe_relation

Class Method Details

.build_csv_instance(io, options) ⇒ Object

Makes the CSV require, depending on Ruby version



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# File 'lib/dbagile/io/csv.rb', line 22

def build_csv_instance(io, options)
  if RUBY_VERSION >= "1.9.0"
    require 'csv'
    options = normalize_options(options)
    csv_options = options.dup.delete_if{|key,value| !::CSV::DEFAULT_OPTIONS.key?(key)}
    [::CSV.new(io, csv_options), options]
  else
    require 'faster_csv'
    options = normalize_options(options)
    csv_options = options.dup.delete_if{|key,value| !FasterCSV::DEFAULT_OPTIONS.key?(key)}
    [FasterCSV.new(io, csv_options), options]
  end
end

.from_csv(input, options = {}) ⇒ Object

If a block is given yields it with each tuple that can be loaded from the CSV input and returns nil. Otherwise, reads the CSV input and returns an array of tuples.



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# File 'lib/dbagile/io/csv.rb', line 70

def from_csv(input, options = {})
  # Creates a CSV inputer with options
  csv, options = build_csv_instance(input, options)
  if ts = options[:type_system]
    converter = lambda{|field| ts.parse_literal(field)}
    csv.header_convert(&converter)
    csv.convert(&converter)
  end
  
  # Load data now
  ts = options[:type_system]
  if block_given?
    csv.each do |row|
      next if row.header_row?
      yield(row.to_hash)
    end
  else
    tuples = []
    csv.each do |row|
      next if row.header_row?
      tuples << row.to_hash
    end
    tuples
  end
end

.normalize_options(options) ⇒ Object

Normalizes CSV options from DBAgile options



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# File 'lib/dbagile/io/csv.rb', line 7

def normalize_options(options)
  if options[:type_system]
    options[:headers] = true unless options.key?(:headers)
    options[:quote_char] = "'" unless options.key?(:quote_char)
    options[:force_quotes] = true unless options.key?(:force_quotes)
  end
  if options[:headers]
    options[:write_headers] = true 
    options[:return_headers] = true 
  end
  options
end

.to_csv(data, columns, buffer = "", options = {}) ⇒ ...

Outputs some data as a CSV string.

Returns:

  • (...) —

    the buffer itself



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# File 'lib/dbagile/io/csv.rb', line 42

def to_csv(data, columns, buffer = "", options = {})
  # Creates a CSV outputter with options
  csv, options = build_csv_instance(buffer, options)
  
  # Write header if required
  if options[:headers]
    if ts = options[:type_system]
      csv << columns.collect{|c| ts.to_literal(c)}
    else
      csv << columns
    end
  end
  
  # Write tuples now
  with_type_safe_relation(data, options) do |tuple|
    csv << columns.collect{|c| tuple[c]}
  end
  
  # Return buffer
  buffer
end