Module: TableDisplay

Defined in:
lib/table_display.rb,
lib/table_display/version.rb

Constant Summary collapse

VERSION = 
'0.5.0'

Instance Method Summary collapse

Instance Method Details

#to_table(*args) ⇒ Object 



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# File 'lib/table_display.rb', line 2

def to_table(*args)
  options = args.last.is_a?(Hash) ? args.pop : {}
  extra_methods = args.length > 0 ? args.collect(&:to_s) : []
  extra_methods += Array(options.delete(:methods)) if options[:methods]
  only_attributes = Array(options.delete(:only)) if options[:only]
  only_attributes ||= [] if args.length > 0
  except_attributes = Array(options.delete(:except)) if options[:except]
  except_attributes = (except_attributes + except_attributes.collect(&:to_s)).uniq if except_attributes.present? # we have to keep string and symbol arguments separate for hashes, which may not have 'indifferent access'
  display_inspect = options.nil? || !options.has_key?(:inspect) || options.delete(:inspect)
  raise "unknown options passed to to_table: #{options.keys.to_sentence}" unless options.blank?
  
  column_lengths = ActiveSupport::OrderedHash.new
  
  data = []
  if only_attributes
    # we've been given an explicit list of attributes to display
    only_attributes.each {|attribute| column_lengths[attribute] = 0}
  else
    # find all the attribute names
    each do |record|
      next if record.nil?
    
      # ActiveRecord's #attributes implementation iterates over #attribute_names adding a duped value to the output hash for each entry, so
      # it's actually more expensive to get the keys and values in one go using #attributes than it is for us to work off #attribute_names ourselves.
      if record.respond_to?(:attribute_names)
        # an ActiveModel instance
        attribute_names = record.attribute_names
      elsif Object.const_defined?(:OpenStruct) && record.is_a?(OpenStruct)
        # OpenStruct has a crappy API, #inspect will show the attributes but there's no public way to get a list of them!
        record = record.instance_variable_get("@table")
        attribute_names = record.keys
      elsif record.respond_to?(:attributes)
        # something like an ActiveResource, which doesn't implement attribute_names but does implement attributes
        attribute_names = record.attributes.keys
      else
        # hopefully something like a hash
        attribute_names = record.keys
      end
    
      if attribute_names.any? {|name| column_lengths[name].nil?} # optimisation, in most use cases all records will have the same type and the same attributes, so we needn't run this for each - but we do handle varying attribute lists, and attributes that are not columns on the model (calculated columns etc.)
        # for ActiveRecord classes, we look at the .columns explicitly so we can keep them in the right order
        columns_to_check = record.is_a?(ActiveRecord::Base) ? ((record.class.columns.collect(&:name) & attribute_names) + attribute_names).uniq : attribute_names
        columns_to_check.each do |name|
          next if (only_attributes && !only_attributes.include?(name)) || (except_attributes && except_attributes.include?(name))
          column_lengths[name] = 0 # the values of columns are the maximum width of value seen; when we come to print out, if the max seen is zero then the attribute has never actually been seen (eg. when a find(:all, :select => ...) has been used to exclude some of the database columns from the resultset), and we hide the column.
        end
      end
    end
  end

  # also add any :methods given to the list
  extra_methods.each {|name| column_lengths[name] = 0}
  
  each do |record|
    # add the values for all the columns in our list in order they are
    data << column_lengths.collect do |attribute, max_width|
      value = record.is_a?(Hash) ? record[attribute] : record.send(attribute)
      string_value = display_inspect ? value.inspect : (value.is_a?(String) ? value : value.to_s)
      column_lengths[attribute] = string_value.mb_chars.length if string_value.mb_chars.length > max_width
      value.is_a?(Numeric) ? value : string_value # keep Numeric values as-is for now, so we can handle them specially in the output below
    end
  end
  
  return [] if data.empty?
  
  # build the table header
  separator_string = "+"
  heading_string   = "|"
  column_lengths.each do |attribute, max_width|
    next unless max_width > 0 # skip any columns we never actually saw
    name = attribute.to_s
    
    # the column needs to fit the column header as well as the values
    if name.mb_chars.length > max_width
      column_lengths[attribute] = max_width = name.mb_chars.length
    end
    
    separator_string << '-'*(max_width + 2) << '+'
    heading_string   << ' ' << name.ljust(max_width) << ' |'
  end
  
  rows = [separator_string, heading_string, separator_string]
  data.each do |data_row|
    data_string = "|"
    column_lengths.each_with_index do |(attribute, max_width), index|
      next unless max_width > 0 # skip any columns we never actually saw
      value = data_row[index]
      if value.is_a?(Numeric)
        data_string << ' ' << (display_inspect ? value.inspect : value.to_s).mb_chars.rjust(max_width) << ' |'
      else
        data_string << ' ' << value.mb_chars.ljust(max_width) << ' |'
      end
    end
    rows << data_string
  end
  rows << separator_string
end