Class: CsvSerializer

Inherits:
Object
  • Object
show all
Defined in:
lib/csv_serializer.rb

Class Method Summary collapse

Class Method Details

.dump(data) ⇒ Object 



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# File 'lib/csv_serializer.rb', line 15

def self.dump(data)
  # takes something that behaves like an Array of Hashes, and returns a CSV string.

  headers = data.try(:first).present? ? data.first.keys : []
  CSV.generate(headers: headers, write_headers: true) do |csv|
    data.try(:map) do |data_hash|
      csv << headers.map { |key| data_hash[key] }
    end
  end
end

.load(csv_string) ⇒ Object 



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# File 'lib/csv_serializer.rb', line 6

def self.load(csv_string)
  # takes a CSV string, and returns an Array of Hashes
  # the keys are the column names and the values are the values.
  # keys and values will all be strings.

  csv_table = CSV.parse(csv_string.present? ? csv_string : '', headers: :first_row)
  csv_table.map { |csv_row| csv_row.to_hash }
end

.load_from_s3_file(key, num_rows = nil, headers = true) ⇒ Object 



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# File 'lib/csv_serializer.rb', line 26

def self.load_from_s3_file(key, num_rows=nil, headers=true)
  # load from an CSV file in s3 and returns the headers (if headers=true) and the rows in 2-D array
  # params:
  #   file: s3 key
  #   num_rows: maximum number of rows to return
  #   headers: does the csv file has a header row?
  #

  reader = AwsS3.pipe_reader(key)
  rows = []
  header_row = nil
  CSV.new(reader, headers: true, return_headers: true).each_with_index do |row, n|
    break if num_rows && n > num_rows

    if headers && n == 0
      header_row = row.fields
    else
      rows << row.fields
    end
  end

  return [header_row, rows]
end