require 'nokogiri' require 'date' module Agents class WebsiteAgent < Agent include WebRequestConcern can_dry_run! can_order_created_events! no_bulk_receive! default_schedule "every_12h" UNIQUENESS_LOOK_BACK = 200 UNIQUENESS_FACTOR = 3 description <<~MD The Website Agent scrapes a website, XML document, or JSON feed and creates Events based on the results. Specify a `url` and select a `mode` for when to create Events based on the scraped data, either `all`, `on_change`, or `merge` (if fetching based on an Event, see below). The `url` option can be a single url, or an array of urls (for example, for multiple pages with the exact same structure but different content to scrape). The WebsiteAgent can also scrape based on incoming events. * Set the `url_from_event` option to a [Liquid](https://github.com/huginn/huginn/wiki/Formatting-Events-using-Liquid) template to generate the url to access based on the Event. (To fetch the url in the Event's `url` key, for example, set `url_from_event` to `{{ url }}`.) * Alternatively, set `data_from_event` to a [Liquid](https://github.com/huginn/huginn/wiki/Formatting-Events-using-Liquid) template to use data directly without fetching any URL. (For example, set it to `{{ html }}` to use HTML contained in the `html` key of the incoming Event.) * If you specify `merge` for the `mode` option, Huginn will retain the old payload and update it with new values. # Supported Document Types The `type` value can be `xml`, `html`, `json`, or `text`. To tell the Agent how to parse the content, specify `extract` as a hash with keys naming the extractions and values of hashes. Note that for all of the formats, whatever you extract MUST have the same number of matches for each extractor except when it has `repeat` set to true. E.g., if you're extracting rows, all extractors must match all rows. For generating CSS selectors, something like [SelectorGadget](http://selectorgadget.com) may be helpful. For extractors with `hidden` set to true, they will be excluded from the payloads of events created by the Agent, but can be used and interpolated in the `template` option explained below. For extractors with `repeat` set to true, their first matches will be included in all extracts. This is useful such as when you want to include the title of a page in all events created from the page. # Scraping HTML and XML When parsing HTML or XML, these sub-hashes specify how each extraction should be done. The Agent first selects a node set from the document for each extraction key by evaluating either a CSS selector in `css` or an XPath expression in `xpath`. It then evaluates an XPath expression in `value` (default: `.`) on each node in the node set, converting the result into a string. Here's an example: "extract": { "url": { "css": "#comic img", "value": "@src" }, "title": { "css": "#comic img", "value": "@title" }, "body_text": { "css": "div.main", "value": "string(.)" }, "page_title": { "css": "title", "value": "string(.)", "repeat": true } } or "extract": { "url": { "xpath": "//*[@class="blog-item"]/a/@href", "value": "." "title": { "xpath": "//*[@class="blog-item"]/a", "value": "normalize-space(.)" }, "description": { "xpath": "//*[@class="blog-item"]/div[0]", "value": "string(.)" } } "@_attr_" is the XPath expression to extract the value of an attribute named _attr_ from a node (such as "@href" from a hyperlink), and `string(.)` gives a string with all the enclosed text nodes concatenated without entity escaping (such as `&`). To extract the innerHTML, use `./node()`; and to extract the outer HTML, use `.`. You can also use [XPath functions](https://www.w3.org/TR/xpath/#section-String-Functions) like `normalize-space` to strip and squeeze whitespace, `substring-after` to extract part of a text, and `translate` to remove commas from formatted numbers, etc. Instead of passing `string(.)` to these functions, you can just pass `.` like `normalize-space(.)` and `translate(., ',', '')`. Beware that when parsing an XML document (i.e. `type` is `xml`) using `xpath` expressions, all namespaces are stripped from the document unless the top-level option `use_namespaces` is set to `true`. For extraction with `raw` set to true, each value will be returned as is without any conversion instead of stringifying them. This is useful when you want to extract a number, a boolean value, or an array of strings. For extraction with `single_array` set to true, all matches will be extracted into an array. This is useful when extracting list elements or multiple parts of a website that can only be matched with the same selector. # Scraping JSON When parsing JSON, these sub-hashes specify [JSONPaths](http://goessner.net/articles/JsonPath/) to the values that you care about. Sample incoming event: { "results": { "data": [ { "title": "Lorem ipsum 1", "description": "Aliquam pharetra leo ipsum." "price": 8.95 }, { "title": "Lorem ipsum 2", "description": "Suspendisse a pulvinar lacus." "price": 12.99 }, { "title": "Lorem ipsum 3", "description": "Praesent ac arcu tellus." "price": 8.99 } ] } } Sample rule: "extract": { "title": { "path": "results.data[*].title" }, "description": { "path": "results.data[*].description" } } In this example the `*` wildcard character makes the parser to iterate through all items of the `data` array. Three events will be created as a result. Sample outgoing events: [ { "title": "Lorem ipsum 1", "description": "Aliquam pharetra leo ipsum." }, { "title": "Lorem ipsum 2", "description": "Suspendisse a pulvinar lacus." }, { "title": "Lorem ipsum 3", "description": "Praesent ac arcu tellus." } ] The `extract` option can be skipped for the JSON type, causing the full JSON response to be returned. # Scraping Text When parsing text, each sub-hash should contain a `regexp` and `index`. Output text is matched against the regular expression repeatedly from the beginning through to the end, collecting a captured group specified by `index` in each match. Each index should be either an integer or a string name which corresponds to (?<name>...). For example, to parse lines of word: definition, the following should work: "extract": { "word": { "regexp": "^(.+?): (.+)$", "index": 1 }, "definition": { "regexp": "^(.+?): (.+)$", "index": 2 } } Or if you prefer names to numbers for index: "extract": { "word": { "regexp": "^(?.+?): (?.+)$", "index": "word" }, "definition": { "regexp": "^(?.+?): (?.+)$", "index": "definition" } } To extract the whole content as one event: "extract": { "content": { "regexp": "\\A(?m:.)*\\z", "index": 0 } } Beware that `.` does not match the newline character (LF) unless the `m` flag is in effect, and `^`/`$` basically match every line beginning/end. See [this document](http://ruby-doc.org/core-#{RUBY_VERSION}/doc/regexp_rdoc.html) to learn the regular expression variant used in this service. # General Options Can be configured to use HTTP basic auth by including the `basic_auth` parameter with `"username:password"`, or `["username", "password"]`. Set `expected_update_period_in_days` to the maximum amount of time that you'd expect to pass between Events being created by this Agent. This is only used to set the "working" status. Set `uniqueness_look_back` to limit the number of events checked for uniqueness (typically for performance). This defaults to the larger of #{UNIQUENESS_LOOK_BACK} or #{UNIQUENESS_FACTOR}x the number of detected received results. Set `force_encoding` to an encoding name (such as `UTF-8` and `ISO-8859-1`) if the website is known to respond with a missing, invalid, or wrong charset in the Content-Type header. Below are the steps used by Huginn to detect the encoding of fetched content: 1. If `force_encoding` is given, that value is used. 2. If the Content-Type header contains a charset parameter, that value is used. 3. When `type` is `html` or `xml`, Huginn checks for the presence of a BOM, XML declaration with attribute "encoding", or an HTML meta tag with charset information, and uses that if found. 4. Huginn falls back to UTF-8 (not ISO-8859-1). Set `user_agent` to a custom User-Agent name if the website does not like the default value (`#{default_user_agent}`). The `headers` field is optional. When present, it should be a hash of headers to send with the request. Set `disable_ssl_verification` to `true` to disable ssl verification. Set `unzip` to `gzip` to inflate the resource using gzip. Set `http_success_codes` to an array of status codes (e.g., `[404, 422]`) to treat HTTP response codes beyond 200 as successes. If a `template` option is given, its value must be a hash, whose key-value pairs are interpolated after extraction for each iteration and merged with the payload. In the template, keys of extracted data can be interpolated, and some additional variables are also available as explained in the next section. For example: "template": { "url": "{{ url | to_uri: _response_.url }}", "description": "{{ body_text }}", "last_modified": "{{ _response_.headers.Last-Modified | date: '%FT%T' }}" } In the `on_change` mode, change is detected based on the resulted event payload after applying this option. If you want to add some keys to each event but ignore any change in them, set `mode` to `all` and put a DeDuplicationAgent downstream. # Liquid Templating In [Liquid](https://github.com/huginn/huginn/wiki/Formatting-Events-using-Liquid) templating, the following variables are available: * `_url_`: The URL specified to fetch the content from. When parsing `data_from_event`, this is not set. * `_response_`: A response object with the following keys: * `status`: HTTP status as integer. (Almost always 200) When parsing `data_from_event`, this is set to the value of the `status` key in the incoming Event, if it is a number or a string convertible to an integer. * `headers`: Response headers; for example, `{{ _response_.headers.Content-Type }}` expands to the value of the Content-Type header. Keys are insensitive to cases and -/_. When parsing `data_from_event`, this is constructed from the value of the `headers` key in the incoming Event, if it is a hash. * `url`: The final URL of the fetched page, following redirects. When parsing `data_from_event`, this is set to the value of the `url` key in the incoming Event. Using this in the `template` option, you can resolve relative URLs extracted from a document like `{{ link | to_uri: _response_.url }}` and `{{ content | rebase_hrefs: _response_.url }}`. # Ordering Events #{description_events_order} MD event_description do if keys = event_keys "Events will have the following fields:\n\n %s" % [ Utils.pretty_print(Hash[event_keys.map { |key| [key, "..."] }]) ] else "Events will be the raw JSON returned by the URL." end end def event_keys extract = options['extract'] or return nil extract.each_with_object([]) { |(key, value), keys| keys << key unless boolify(value['hidden']) } | (options['template'].presence.try!(:keys) || []) end def working? event_created_within?(options['expected_update_period_in_days']) && !recent_error_logs? end def default_options { 'expected_update_period_in_days' => "2", 'url' => "https://xkcd.com", 'type' => "html", 'mode' => "on_change", 'extract' => { 'url' => { 'css' => "#comic img", 'value' => "@src" }, 'title' => { 'css' => "#comic img", 'value' => "@alt" }, 'hovertext' => { 'css' => "#comic img", 'value' => "@title" } } } end def validate_options # Check for required fields errors.add(:base, "either url, url_from_event, or data_from_event are required") unless options['url'].present? || options['url_from_event'].present? || options['data_from_event'].present? errors.add(:base, "expected_update_period_in_days is required") unless options['expected_update_period_in_days'].present? validate_extract_options! validate_template_options! validate_http_success_codes! # Check for optional fields if options['mode'].present? errors.add(:base, "mode must be set to on_change, all or merge") unless %w[on_change all merge].include?(options['mode']) end if options['expected_update_period_in_days'].present? errors.add(:base, "Invalid expected_update_period_in_days format") unless is_positive_integer?(options['expected_update_period_in_days']) end if options['uniqueness_look_back'].present? errors.add(:base, "Invalid uniqueness_look_back format") unless is_positive_integer?(options['uniqueness_look_back']) end validate_web_request_options! end def validate_http_success_codes! consider_success = options["http_success_codes"] if consider_success.present? if consider_success.class != Array errors.add(:http_success_codes, "must be an array and specify at least one status code") elsif consider_success.uniq.count != consider_success.count errors.add(:http_success_codes, "duplicate http code found") elsif consider_success.any? { |e| e.to_s !~ /^\d+$/ } errors.add(:http_success_codes, "please make sure to use only numeric values for code, ex 404, or \"404\"") end end end def validate_extract_options! extraction_type = begin extraction_type() rescue StandardError extraction_type(options) end case extract = options['extract'] when Hash if extract.each_value.any? { |value| !value.is_a?(Hash) } errors.add(:base, 'extract must be a hash of hashes.') else case extraction_type when 'html', 'xml' extract.each do |name, details| details.each do |name,| case name when 'css', 'xpath', 'value', 'repeat', 'hidden', 'raw', 'single_array' # ok else errors.add(:base, "Unknown key #{name.inspect} in extraction details") end end case details['css'] when String # ok when nil case details['xpath'] when String # ok when nil errors.add(:base, "When type is html or xml, all extractions must have a css or xpath attribute (bad extraction details for #{name.inspect})") else errors.add(:base, "Wrong type of \"xpath\" value in extraction details for #{name.inspect}") end else errors.add(:base, "Wrong type of \"css\" value in extraction details for #{name.inspect}") end case details['value'] when String, nil # ok else errors.add(:base, "Wrong type of \"value\" value in extraction details for #{name.inspect}") end end when 'json' extract.each do |name, details| case details['path'] when String # ok when nil errors.add(:base, "When type is json, all extractions must have a path attribute (bad extraction details for #{name.inspect})") else errors.add(:base, "Wrong type of \"path\" value in extraction details for #{name.inspect}") end end when 'text' extract.each do |name, details| case regexp = details['regexp'] when String begin re = Regexp.new(regexp) rescue StandardError => e errors.add(:base, "invalid regexp for #{name.inspect}: #{e.message}") end when nil errors.add(:base, "When type is text, all extractions must have a regexp attribute (bad extraction details for #{name.inspect})") else errors.add(:base, "Wrong type of \"regexp\" value in extraction details for #{name.inspect}") end case index = details['index'] when Integer, /\A\d+\z/ # ok when String if re && !re.names.include?(index) errors.add(:base, "no named capture #{index.inspect} found in regexp for #{name.inspect})") end when nil errors.add(:base, "When type is text, all extractions must have an index attribute (bad extraction details for #{name.inspect})") else errors.add(:base, "Wrong type of \"index\" value in extraction details for #{name.inspect}") end end when /\{/ # Liquid templating else errors.add(:base, "Unknown extraction type #{extraction_type.inspect}") end end when nil unless extraction_type == 'json' errors.add(:base, 'extract is required for all types except json') end else errors.add(:base, 'extract must be a hash') end end def validate_template_options! template = options['template'].presence or return unless Hash === template && template.each_key.all?(String) errors.add(:base, 'template must be a hash of strings.') end end def check check_urls(interpolated['url']) end def check_urls(in_url, existing_payload = {}) return unless in_url.present? Array(in_url).each do |url| check_url(url, existing_payload) end end def check_url(url, existing_payload = {}) unless /\Ahttps?:\/\//i === url error "Ignoring a non-HTTP url: #{url.inspect}" return end uri = Utils.normalize_uri(url) log "Fetching #{uri}" response = faraday.get(uri) raise "Failed: #{response.inspect}" unless consider_response_successful?(response) interpolation_context.stack { interpolation_context['_url_'] = uri.to_s interpolation_context['_response_'] = ResponseDrop.new(response) handle_data(response.body, response.env[:url], existing_payload) } rescue StandardError => e error "Error when fetching url: #{e.message}\n#{e.backtrace.join("\n")}" end def default_encoding case extraction_type when 'html', 'xml' # Let Nokogiri detect the encoding nil else super end end def handle_data(body, url, existing_payload) # Beware, url may be a URI object, string or nil doc = parse(body) if extract_full_json? if store_payload!(previous_payloads(1), doc) log "Storing new result for '#{name}': #{doc.inspect}" create_event payload: existing_payload.merge(doc) end return end output = case extraction_type when 'json' extract_json(doc) when 'text' extract_text(doc) else extract_xml(doc) end num_tuples = output.size or raise "At least one non-repeat key is required" old_events = previous_payloads num_tuples template = options['template'].presence output.each do |extracted| result = extracted.except(*output.hidden_keys) if template result.update(interpolate_options(template, extracted)) end if store_payload!(old_events, result) log "Storing new parsed result for '#{name}': #{result.inspect}" create_event payload: existing_payload.merge(result) end end end def receive(incoming_events) interpolate_with_each(incoming_events) do |event| existing_payload = interpolated['mode'].to_s == "merge" ? event.payload : {} if data_from_event = options['data_from_event'].presence data = interpolate_options(data_from_event) if data.present? handle_event_data(data, event, existing_payload) else error "No data was found in the Event payload using the template #{data_from_event}", inbound_event: event end else url_to_scrape = if url_template = options['url_from_event'].presence interpolate_options(url_template) else interpolated['url'] end check_urls(url_to_scrape, existing_payload) end end end private def consider_response_successful?(response) response.success? || begin consider_success = options["http_success_codes"] consider_success.present? && (consider_success.include?(response.status.to_s) || consider_success.include?(response.status)) end end def handle_event_data(data, event, existing_payload) interpolation_context.stack { interpolation_context['_response_'] = ResponseFromEventDrop.new(event) handle_data(data, event.payload['url'].presence, existing_payload) } rescue StandardError => e error "Error when handling event data: #{e.message}\n#{e.backtrace.join("\n")}" end # This method returns true if the result should be stored as a new event. # If mode is set to 'on_change', this method may return false and update an existing # event to expire further in the future. def store_payload!(old_events, result) case interpolated['mode'].presence when 'on_change' result_json = result.to_json if found = old_events.find { |event| event.payload.to_json == result_json } found.update!(expires_at: new_event_expiration_date) false else true end when 'all', 'merge', '' true else raise "Illegal options[mode]: #{interpolated['mode']}" end end def previous_payloads(num_events) if interpolated['uniqueness_look_back'].present? look_back = interpolated['uniqueness_look_back'].to_i else # Larger of UNIQUENESS_FACTOR * num_events and UNIQUENESS_LOOK_BACK look_back = UNIQUENESS_FACTOR * num_events if look_back < UNIQUENESS_LOOK_BACK look_back = UNIQUENESS_LOOK_BACK end end events.order("id desc").limit(look_back) if interpolated['mode'] == "on_change" end def extract_full_json? !interpolated['extract'].present? && extraction_type == "json" end def extraction_type(interpolated = interpolated()) (interpolated['type'] || begin case interpolated['url'] when /\.(rss|xml)$/i "xml" when /\.json$/i "json" when /\.(txt|text)$/i "text" else "html" end end).to_s end def use_namespaces? if interpolated.key?('use_namespaces') boolify(interpolated['use_namespaces']) else interpolated['extract'].none? { |_name, extraction_details| extraction_details.key?('xpath') } end end def extract_each(&block) interpolated['extract'].each_with_object(Output.new) { |(name, extraction_details), output| if boolify(extraction_details['repeat']) values = Repeater.new { |repeater| block.call(extraction_details, repeater) } else values = [] block.call(extraction_details, values) end log "Values extracted: #{values}" begin output[name] = values rescue UnevenSizeError raise "Got an uneven number of matches for #{interpolated['name']}: #{interpolated['extract'].inspect}" else output.hidden_keys << name if boolify(extraction_details['hidden']) end } end def extract_json(doc) extract_each { |extraction_details, values| log "Extracting #{extraction_type} at #{extraction_details['path']}" Utils.values_at(doc, extraction_details['path']).each { |value| values << value } } end def extract_text(doc) extract_each { |extraction_details, values| regexp = Regexp.new(extraction_details['regexp']) log "Extracting #{extraction_type} with #{regexp}" case index = extraction_details['index'] when /\A\d+\z/ index = index.to_i end doc.scan(regexp) { values << Regexp.last_match[index] } } end def extract_xml(doc) extract_each { |extraction_details, values| case when css = extraction_details['css'] nodes = doc.css(css) when xpath = extraction_details['xpath'] nodes = doc.xpath(xpath) else raise '"css" or "xpath" is required for HTML or XML extraction' end log "Extracting #{extraction_type} at #{xpath || css}" expr = extraction_details['value'] || '.' handle_float = ->(value) { case when value.nan? 'NaN' when value.infinite? if value > 0 'Infinity' else '-Infinity' end when value.to_i == value # Node#xpath() returns any numeric value as float; # convert it to integer as appropriate. value.to_i else value end } jsonify = if boolify(extraction_details['raw']) ->(value) { case value when nil, true, false, String, Integer value when Float handle_float.call(value) when Nokogiri::XML::NodeSet value.map(&jsonify) else value.to_s end } else ->(value) { case value when Float handle_float.call(value).to_s else value.to_s end } end case nodes when Nokogiri::XML::NodeSet node_values = nodes.map { |node| jsonify.call(node.xpath(expr)) } if boolify(extraction_details['single_array']) values << node_values else node_values.each { |value| values << value } end else raise "The result of HTML/XML extraction was not a NodeSet" end } end def parse(data) case type = extraction_type when "xml" doc = Nokogiri::XML(data) # ignore xmlns, useful when parsing atom feeds doc.remove_namespaces! unless use_namespaces? doc when "json" JSON.parse(data) when "html" Nokogiri::HTML(data) when "text" data else raise "Unknown extraction type: #{type}" end end class UnevenSizeError < ArgumentError end class Output def initialize @hash = {} @size = nil @hidden_keys = [] end attr_reader :size attr_reader :hidden_keys def []=(key, value) case size = value.size when Integer if @size && @size != size raise UnevenSizeError, 'got an uneven size' end @size = size end @hash[key] = value end def each @size.times.zip(*@hash.values) do |_index, *values| yield @hash.each_key.lazy.zip(values).to_h end end end class Repeater < Enumerator # Repeater.new { |y| # # ... # y << value # } #=> [value, ...] def initialize(&block) @value = nil super(Float::INFINITY) { |y| loop { y << @value } } catch(@done = Object.new) { block.call(self) } end def <<(value) @value = value throw @done end def to_s "[#{@value.inspect}, ...]" end end # Wraps Faraday::Response class ResponseDrop < LiquidDroppable::Drop def headers HeaderDrop.new(@object.headers) end # Integer value of HTTP status def status @object.status end # The URL def url @object.env.url.to_s end end class ResponseFromEventDrop < LiquidDroppable::Drop def headers headers = begin Faraday::Utils::Headers.from(@object.payload[:headers]) rescue StandardError {} end HeaderDrop.new(headers) end # Integer value of HTTP status def status Integer(@object.payload[:status]) rescue StandardError nil end # The URL def url @object.payload[:url] end end # Wraps Faraday::Utils::Headers class HeaderDrop < LiquidDroppable::Drop def liquid_method_missing(name) @object[name.tr('_', '-')] end end end end