Class: JsonCsv::CsvBuilder

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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(open_csv_handle) ⇒ CsvBuilder

Returns a new instance of CsvBuilder.



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# File 'lib/json_csv/csv_builder.rb', line 14

def initialize(open_csv_handle)
  @known_headers_to_indexes = {}
  @open_csv_handle = open_csv_handle
end

Instance Attribute Details

#known_headers_to_indexes ⇒ Object (readonly)

map of all headers seen by this CsvBuilder, mapped to their column order indexes



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# File 'lib/json_csv/csv_builder.rb', line 12

def known_headers_to_indexes
  @known_headers_to_indexes
end

Class Method Details

.create_csv_without_headers(csv_outfile_path, csv_write_mode = 'wb') ⇒ Object

Writes out a CSV file that does NOT contain a header row. Only data values. Returns an array of headers that correspond to the written-out CSV file’s columns.

Why don’t we include CSV headers in the CSV? Because don’t know what set of headers we’re working with while we dynamically create this CSV. Different JSON documents may or may not all contain the same headers. For this reason, this is more of an internal method that isn’t called directly by users of this gem.



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# File 'lib/json_csv/csv_builder.rb', line 39

def self.create_csv_without_headers(csv_outfile_path, csv_write_mode = 'wb')
  csv_builder = nil

  CSV.open(csv_outfile_path, csv_write_mode) do |csv|
    csv_builder = new(csv)
    yield csv_builder
  end

  csv_builder.known_headers_to_indexes.keys
end

.original_header_indexes_to_sorted_indexes(csv_headers, column_header_comparator) ⇒ Object 



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# File 'lib/json_csv/csv_builder.rb', line 50

def self.original_header_indexes_to_sorted_indexes(csv_headers, column_header_comparator)
  original_headers_to_indexes = Hash[csv_headers.map.with_index { |header, index| [header, index] }]
  headers_to_sorted_indexes = Hash[csv_headers.sort(&column_header_comparator).map.with_index do |header, index|
                                     [header, index]
                                   end ]
  original_to_sorted_index_map = {}
  original_headers_to_indexes.each do |header, original_index|
    original_to_sorted_index_map[original_index] = headers_to_sorted_indexes[header]
  end
  original_to_sorted_index_map
end

Instance Method Details

#add(json_hash) ⇒ Object

Adds data from the given json hash to the CSV we’re building.



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# File 'lib/json_csv/csv_builder.rb', line 20

def add(json_hash)
  row_to_write = []
  JsonCsv.json_hash_to_flat_csv_row_hash(json_hash).each do |column_header, cell_value|
    unless known_headers_to_indexes.key?(column_header)
      known_headers_to_indexes[column_header] =
        known_headers_to_indexes.length
    end
    row_to_write[known_headers_to_indexes[column_header]] = cell_value
  end
  @open_csv_handle << row_to_write
end