Module: JsonCsv::JsonToCsv::ClassMethods

Defined in:
lib/json_csv/json_to_csv.rb

Constant Summary collapse

DEFAULT_HEADER_SORT_COMPARATOR = 
lambda do |header1, header2|
  # Ensure correct alphabetical sorting AND numeric sorting via zero-padding of numbers
  header1_with_zero_padding = header1.gsub(/(?<=\[)\d+(?=\])/) { |capture| capture.to_i.to_s.rjust(5, '0') }
  header2_with_zero_padding = header2.gsub(/(?<=\[)\d+(?=\])/) { |capture| capture.to_i.to_s.rjust(5, '0') }
  header1_with_zero_padding <=> header2_with_zero_padding
end

Instance Method Summary collapse

Instance Method Details

#create_csv_for_json_records(csv_outfile_path, header_sort_comparator = DEFAULT_HEADER_SORT_COMPARATOR, &block) ⇒ Object

Example usage: create_csv_for_json_records(‘/path/to/file.csv’) do |csv_builder|

json_docs.each do |json_doc|
  csv_builder.add(json_hash)
end

end



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# File 'lib/json_csv/json_to_csv.rb', line 31

def create_csv_for_json_records(csv_outfile_path, header_sort_comparator = DEFAULT_HEADER_SORT_COMPARATOR, &block)
  csv_temp_outfile_path = "#{csv_outfile_path}.temp"

  begin
    # Step 1: Build CSV with unsorted headers in temp file
    csv_headers = JsonCsv::CsvBuilder.create_csv_without_headers(csv_temp_outfile_path, 'wb', &block)

    # Step 2: Sort CSV columns by header, based on column_header_comparator
    original_to_sorted_index_map = JsonCsv::CsvBuilder.original_header_indexes_to_sorted_indexes(
      csv_headers, header_sort_comparator
    )
    CSV.open(csv_outfile_path, 'wb') do |final_csv|
      # Open temporary CSV for reading
      CSV.open(csv_temp_outfile_path, 'rb') do |temp_csv|
        # write out ordered header row
        reordered_header_row = []
        csv_headers.each_with_index do |header, index|
          reordered_header_row[original_to_sorted_index_map[index]] = header
        end

        final_csv << reordered_header_row

        temp_csv.each do |temp_csv_row|
          reordered_temp_csv_row = []
          # write out ordered data row
          temp_csv_row.each_with_index do |cell_value, index|
            reordered_temp_csv_row[original_to_sorted_index_map[index]] = cell_value
          end
          final_csv << reordered_temp_csv_row
        end
      end
    end
  ensure
    # Always delete the temporary CSV
    FileUtils.rm_f(csv_temp_outfile_path)
  end
end

#default_header_comparison(header1, header2) ⇒ Object 



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# File 'lib/json_csv/json_to_csv.rb', line 21

def default_header_comparison(header1, header2)
  DEFAULT_HEADER_SORT_COMPARATOR.call(header1, header2)
end

#flatten_hash(obj, parent_path = '', flat_hash_to_build = {}) ⇒ Object

This method calls itself recursively while flattening a hash, and during this sequence of calls the obj param may either be a hash or an array.



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# File 'lib/json_csv/json_to_csv.rb', line 82

def flatten_hash(obj, parent_path = '', flat_hash_to_build = {})
  if obj.is_a?(Hash)
    obj.each do |key, val|
      if key_contains_unallowed_characters?(key)
        raise ArgumentError,
              'Cannot deal with hash keys that contain "[" or "]" or "." because '\
              'these characters have special meanings in CSV headers.'
      end

      path = parent_path + (parent_path.empty? ? '' : '.') + key
      flatten_hash(val, path, flat_hash_to_build)
    end
  elsif obj.is_a?(Array)
    obj.each_with_index do |el, index|
      path = parent_path + "[#{index}]"
      flatten_hash(el, path, flat_hash_to_build)
    end
  else
    flat_hash_to_build[parent_path] = obj unless obj.nil? || obj == '' # ignore nil or empty string values
  end

  flat_hash_to_build
end

#json_hash_to_flat_csv_row_hash(json_hash) ⇒ Object

Converts the given json_hash into a flat csv hash, converting all values to strings (because CSVs are dumb and don’t store info about data types) Set first_index to 1 if you want the first element in an array to



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# File 'lib/json_csv/json_to_csv.rb', line 73

def json_hash_to_flat_csv_row_hash(json_hash)
  flat = flatten_hash(json_hash)
  # Convert values to strings because in the CSV file, all values are strings
  flat.each { |key, val| flat[key] = val.nil? ? '' : val.to_s }
  flat
end

#key_contains_unallowed_characters?(key) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/json_csv/json_to_csv.rb', line 106

def key_contains_unallowed_characters?(key)
  return true if key.index('[') || key.index(']') || key.index('.')

  false
end