class Mechanize::PluggableParser

Mechanize allows different parsers for different content types. Mechanize uses PluggableParser to determine which parser to use for any content type. To use your own parser or to change the default parsers, register them with this class through Mechanize#pluggable_parser.

The default parser for unregistered content types is Mechanize::File.

The module Mechanize::Parser provides basic functionality for any content type, so you may use it in custom parsers you write. For small files you wish to perform in-memory operations on, you should subclass Mechanize::File. For large files you should subclass Mechanize::Download as the content is only loaded into memory in small chunks.

When writing your own pluggable parser, be sure to provide a method body that returns a String containing the response body for compatibility with Mechanize#get_file.

Example¶ ↑

To create your own parser, just create a class that takes four parameters in the constructor. Here is an example of registering a parser that handles CSV files:

require 'csv'

class CSVParser < Mechanize::File
  attr_reader :csv

  def initialize uri = nil, response = nil, body = nil, code = nil
    super uri, response, body, code
    @csv = CSV.parse body
  end
end

agent = Mechanize.new
agent.pluggable_parser.csv = CSVParser
agent.get('http://example.com/test.csv')  # => CSVParser

Now any response with a content type of 'text/csv' will initialize a CSVParser and return that object to the caller.

To register a parser for a content type that Mechanize does not know about, use the hash syntax:

agent.pluggable_parser['text/something'] = SomeClass

To set the default parser, use default:

agent.pluggable_parser.default = Mechanize::Download

Now all unknown content types will be saved to disk and not loaded into memory.

Constants

CONTENT_TYPES
InvalidContentTypeError

Attributes

default[RW]

Public Class Methods

new() click to toggle source

# File lib/mechanize/pluggable_parsers.rb, line 83
def initialize
  @parsers = {
    CONTENT_TYPES[:html]  => Mechanize::Page,
    CONTENT_TYPES[:xhtml] => Mechanize::Page,
    CONTENT_TYPES[:wap]   => Mechanize::Page,
    'image'               => Mechanize::Image,
    'text/xml'            => Mechanize::XmlFile,
    'application/xml'     => Mechanize::XmlFile,
  }

  @default = Mechanize::File
end

Public Instance Methods

[](content_type) click to toggle source

Retrieves the parser for content_type content

# File lib/mechanize/pluggable_parsers.rb, line 162
def [](content_type)
  @parsers[content_type]
end

[]=(content_type, klass) click to toggle source

Sets the parser for content_type content to klass

The content_type may either be a full MIME type a simplified MIME type ('text/x-csv' simplifies to 'text/csv') or a media type like 'image'.

# File lib/mechanize/pluggable_parsers.rb, line 172
def []= content_type, klass
  register_parser content_type, klass
end

csv=(klass) click to toggle source

Registers klass as the parser for text/csv content

# File lib/mechanize/pluggable_parsers.rb, line 146
def csv=(klass)
  register_parser(CONTENT_TYPES[:csv], klass)
end

html=(klass) click to toggle source

Registers klass as the parser for text/html and application/xhtml+xml content

# File lib/mechanize/pluggable_parsers.rb, line 124
def html=(klass)
  register_parser(CONTENT_TYPES[:html], klass)
  register_parser(CONTENT_TYPES[:xhtml], klass)
end

parser(content_type) click to toggle source

Returns the parser registered for the given content_type

# File lib/mechanize/pluggable_parsers.rb, line 99
def parser content_type
  return default unless content_type

  parser = @parsers[content_type]

  return parser if parser

  mime_type = MIME::Type.new content_type

  parser = @parsers[mime_type.to_s] ||
           @parsers[mime_type.simplified] ||
           @parsers[mime_type.media_type] ||
           default
rescue InvalidContentTypeError
  default
end

pdf=(klass) click to toggle source

Registers klass as the parser for application/pdf content

# File lib/mechanize/pluggable_parsers.rb, line 139
def pdf=(klass)
  register_parser(CONTENT_TYPES[:pdf], klass)
end

xhtml=(klass) click to toggle source

Registers klass as the parser for application/xhtml+xml content

# File lib/mechanize/pluggable_parsers.rb, line 132
def xhtml=(klass)
  register_parser(CONTENT_TYPES[:xhtml], klass)
end

xml=(klass) click to toggle source

Registers klass as the parser for text/xml content

# File lib/mechanize/pluggable_parsers.rb, line 153
def xml=(klass)
  CONTENT_TYPES[:xml].each do |content_type|
    register_parser content_type, klass
  end
end