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Ruby DBF Library Fixes

01.29.2008
| 5016 views |
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        A handful of fixes/enhancements for the "dbf" Rubygem.

# example.rb
require 'rubygems'
require 'dbf'
require 'dbf_fixes'

table = DBF::Table.new('/path/to/table.dbf', :in_memory => false)
table.each_record do |record|
  # do something here
  # with in_memory=>false tables, each_record is much more efficient
  # because it reads directly from disk 
end


# dbf_fixes.rb
module DBF
  class Record
    private

    # fix bug in DBF code (or workaround bug in FoxPro dbf files; I don't know :-)
    def initialize_values(columns)
      columns.each do |column|
        case column.type
        when 'I' # added by Tim - I don't understand this much, but it seems to work
          @attributes[column.name] = @data.read(column.length).unpack("I").first
        when 'N' # number
          @attributes[column.name] = column.decimal.zero? ? unpack_string(column).to_i : unpack_string(column).to_f
        when 'D' # date
          raw = unpack_string(column).strip
          unless raw.empty?
            begin
              parts = raw.match(DATE_REGEXP).to_a.slice(1,3).map {|n| n.to_i}
              @attributes[column.name] = Time.gm(*parts)
            rescue
              parts = raw.match(DATE_REGEXP).to_a.slice(1,3).map {|n| n.to_i}
              @attributes[column.name] = Date.new(*parts)
            end
          end
        when 'M' # memo
          starting_block = unpack_string(column).to_i
          @attributes[column.name] = read_memo(starting_block)
        when 'L' # logical
          @attributes[column.name] = unpack_string(column) =~ /^(y|t)$/i ? true : false
        else
          @attributes[column.name] = unpack_string(column).strip
        end
      end
    end

    # don't know why, but accessors stopped working for me.
    def define_accessors
      @table.columns.each do |column|
        underscored_column_name = underscore(column.name)
        if @table.options[:accessors]
          self.class.send :define_method, underscored_column_name do
            @attributes[column.name]
          end
          @@accessors_defined = true
        end
      end
    end
  end

  class Table
    # more efficient iterator (so we don't load everything)
    def each_record
      if options[:in_memory] and @records
        @records.each { |r| yield(r) }
      else
        0.upto(@record_count - 1) do |n|
          seek_to_record(n)
          yield(DBF::Record.new(self)) unless deleted_record?
        end
      end
    end
  end
end