A CSV::Row is part Array and part Hash. It retains an order for the fields and allows duplicates just as an Array would, but also allows you to access fields by name just as you could if they were in a Hash.
All rows returned by CSV will be constructed from this class, if header row processing is activated.
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- fetch,
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- fields
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| [R] | row | Internal data format used to compare equality. |
Construct a new CSV::Row from headers
and fields, which are expected to be Arrays. If one Array is
shorter than the other, it will be padded with nil objects.
The optional header_row parameter can be set to
true to indicate, via #header_row? and #field_row?, that this is a
header row. Otherwise, the row is assumes to be a field row.
A CSV::Row object supports the following Array methods through delegation:
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empty?()
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length()
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size()
If a two-element Array is provided, it is assumed to be a header and field
and the pair is appended. A Hash works the same
way with the key being the header and the value being the field. Anything
else is assumed to be a lone field which is appended with a
nil header.
This method returns the row for chaining.
# File lib/csv.rb, line 375 def <<(arg) if arg.is_a?(Array) and arg.size == 2 # appending a header and name @row << arg elsif arg.is_a?(Hash) # append header and name pairs arg.each { |pair| @row << pair } else # append field value @row << [nil, arg] end self # for chaining end
Returns true if this row contains the same headers and fields
in the same order as other.
Looks up the field by the semantics described in #field and assigns the
value.
Assigning past the end of the row with an index will set all pairs between
to [nil, nil]. Assigning to an unused header appends the new
pair.
# File lib/csv.rb, line 342 def []=(*args) value = args.pop if args.first.is_a? Integer if @row[args.first].nil? # extending past the end with index @row[args.first] = [nil, value] @row.map! { |pair| pair.nil? ? [nil, nil] : pair } else # normal index assignment @row[args.first][1] = value end else index = index(*args) if index.nil? # appending a field self << [args.first, value] else # normal header assignment @row[index][1] = value end end end
Used to remove a pair from the row by header or
index. The pair is located as described in #field. The deleted pair is returned,
or nil if a pair could not be found.
The provided block is passed a header and field for each pair
in the row and expected to return true or false,
depending on whether the pair should be deleted.
This method returns the row for chaining.
Yields each pair of the row as header and field tuples (much like iterating over a Hash).
Support for Enumerable.
This method returns the row for chaining.
This method will fetch the field value by header. It has the
same behavior as Hash#fetch: if
there is a field with the given header, its value is returned.
Otherwise, if a block is given, it is yielded the header and
its result is returned; if a default is given as the second
argument, it is returned; otherwise a KeyError is raised.
# File lib/csv.rb, line 305 def fetch(header, *varargs) raise ArgumentError, "Too many arguments" if varargs.length > 1 pair = @row.assoc(header) if pair pair.last else if block_given? yield header elsif varargs.empty? raise KeyError, "key not found: #{header}" else varargs.first end end end
This method will return the field value by header or
index. If a field is not found, nil is returned.
When provided, offset ensures that a header match occurrs on
or later than the offset index. You can use this to find
duplicate headers, without resorting to hard-coding exact indices.
# File lib/csv.rb, line 283 def field(header_or_index, minimum_index = 0) # locate the pair finder = header_or_index.is_a?(Integer) ? :[] : :assoc pair = @row[minimum_index..-1].send(finder, header_or_index) # return the field if we have a pair pair.nil? ? nil : pair.last end
Returns true if data matches a field in this row,
and false otherwise.
Returns true if this is a field row.
This method accepts any number of arguments which can be headers, indices, Ranges of either, or two-element Arrays containing a header and offset. Each argument will be replaced with a field lookup as described in #field.
If called with no arguments, all fields are returned.
# File lib/csv.rb, line 441 def fields(*headers_and_or_indices) if headers_and_or_indices.empty? # return all fields--no arguments @row.map { |pair| pair.last } else # or work like values_at() headers_and_or_indices.inject(Array.new) do |all, h_or_i| all + if h_or_i.is_a? Range index_begin = h_or_i.begin.is_a?(Integer) ? h_or_i.begin : index(h_or_i.begin) index_end = h_or_i.end.is_a?(Integer) ? h_or_i.end : index(h_or_i.end) new_range = h_or_i.exclude_end? ? (index_begin...index_end) : (index_begin..index_end) fields.values_at(new_range) else [field(*Array(h_or_i))] end end end end
Returns true if there is a field with the given
header.
Returns true if name is a header for this row,
and false otherwise.
Returns true if this is a header row.
Returns the headers of this row.
This method will return the index of a field with the provided
header. The offset can be used to locate
duplicate header names, as described in #field.
A summary of fields, by header, in an ASCII compatible String.
# File lib/csv.rb, line 537 def inspect str = ["#<", self.class.to_s] each do |header, field| str << " " << (header.is_a?(Symbol) ? header.to_s : header.inspect) << ":" << field.inspect end str << ">" begin str.join('') rescue # any encoding error str.map do |s| e = Encoding::Converter.asciicompat_encoding(s.encoding) e ? s.encode(e) : s.force_encoding("ASCII-8BIT") end.join('') end end
A shortcut for appending multiple fields. Equivalent to:
args.each { |arg| csv_row << arg }
This method returns the row for chaining.
Returns the row as a CSV String. Headers are not used. Equivalent to:
csv_row.fields.to_csv( options )