Class: FlatKit::Command::Cat

Inherits:
FlatKit::Command show all
Defined in:
lib/flat_kit/command/cat.rb

Overview

TODO: Implement the –flatten commandline switch

Instance Attribute Summary

Attributes inherited from FlatKit::Command

#argv, #env, #logger, #opts, #readers, #writer

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from FlatKit::Command

for, #initialize, names

Methods included from DescendantTracker

#children, #find_child, #inherited

Constructor Details

This class inherits a constructor from FlatKit::Command

Class Method Details

.description ⇒ Object 



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# File 'lib/flat_kit/command/cat.rb', line 9

def self.description
  "Concatenate files together that have the same structure."
end

.name ⇒ Object 



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# File 'lib/flat_kit/command/cat.rb', line 5

def self.name
  "cat"
end

.parser ⇒ Object 



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# File 'lib/flat_kit/command/cat.rb', line 13

def self.parser
  ::Optimist::Parser.new do
    banner "#{Cat.description}"
    banner ""

    banner <<~BANNER
    Concatenates files that have the same field structure together into
    a single file. The files can be of different formats, but must have
    the same fields and names.

    This is probably most easily usable as a way to convert CSV to JSON
    and vice versa.

    The flatfile type(s) will be automatically determined by the file name.
    If the inputs or output is not a file, but from stdin or stdout then
    the input and output types must be specified.

    NOTE: If converting from JSON to CSV and the input JSON does not have
          every possible field on ever record, then the output csv iwll
          be corrupted.

          In this case the input json should be fed through 'flatten' first
          or use the '--flatten' flag which will require an additional pass
          through the input to gather all the fields
    BANNER

    banner <<~USAGE

    Usage:
      fk cat file1.csv file2.csv > combinded.csv
      fk cat --output-format json file1.csv
      fk cat file1.csv.gzip -o file2.json.gzip
      fk cat file1.csv.gzip --output-format json | gzip -c > file1.jsonl.gz

    USAGE

    banner <<~OPTIONS

    Options:

    OPTIONS

    opt :output, "Send the output to the given path instead of standard out.", default: "<stdout>"
    opt :input_format, "Input format, csv or json", default: "auto", short: :none
    opt :output_format, "Output format, csv or json", default: "auto", short: :none
  end
end

Instance Method Details

#call ⇒ Object 



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# File 'lib/flat_kit/command/cat.rb', line 77

def call
  total = 0
  readers.each do |r|
    logger.info "cat #{r.source} to #{writer.destination}"
    r.each do |record|
      writer.write(record)
      total += 1
    end
    logger.info "read #{r.count} records from #{r.source}"
  end
  writer.close
  logger.debug "processed #{writer.count} records"
  logger.debug "read #{total} records"
end

#parse ⇒ Object 



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# File 'lib/flat_kit/command/cat.rb', line 61

def parse
  parser = self.class.parser
  ::Optimist::with_standard_exception_handling(parser) do
    begin
      @opts = parser.parse(argv)
      paths = parser.leftovers

      @readers = ::FlatKit::Reader.create_readers_from_paths(paths: paths, fallback: opts[:input_format])
      @writer  = ::FlatKit::Writer.create_writer_from_path(path: opts[:output], fallback: opts[:output_format],
                                                           reader_format: @readers.first.format_name)
    rescue ::FlatKit::Error => e
      raise ::Optimist::CommandlineError, e.message
    end
  end
end