# SPDX-License-Identifier: AGPL-3.0-or-later """Google Scholar is a freely accessible web search engine that indexes the full text or metadata of scholarly literature across an array of publishing formats and disciplines. Compared to other Google services the Scholar engine has a simple GET REST-API and there does not exists ``async`` API. Even though the API slightly vintage we can make use of the :ref:`google API` to assemble the arguments of the GET request. Configuration ============= .. code:: yaml - name: google scholar engine: google_scholar shortcut: gos Implementations =============== """ import typing as t from urllib.parse import urlencode from datetime import datetime from lxml import html import httpx from searx.utils import ( eval_xpath, eval_xpath_getindex, eval_xpath_list, extract_text, ElementType, ) from searx.exceptions import SearxEngineCaptchaException, SearxEngineAccessDeniedException from searx.engines.google import fetch_traits # pylint: disable=unused-import from searx.engines.google import ( get_google_info, time_range_dict, ) from searx.result_types import EngineResults if t.TYPE_CHECKING: from searx.extended_types import SXNG_Response from searx.search.processors import OnlineParams about = { "website": "https://scholar.google.com", "wikidata_id": "Q494817", "official_api_documentation": "https://developers.google.com/custom-search", "use_official_api": False, "require_api_key": False, "results": "HTML", } # engine dependent config categories = ["science", "scientific publications"] paging = True max_page = 50 """`Google max 50 pages`_ .. _Google max 50 pages: https://github.com/searxng/searxng/issues/2982 """ language_support = True time_range_support = True safesearch = False def request(query: str, params: "OnlineParams") -> None: """Google-Scholar search request""" google_info = get_google_info(params, traits) # subdomain is: scholar.google.xy google_info["subdomain"] = google_info["subdomain"].replace("www.", "scholar.") args = { "q": query, **google_info["params"], "start": (params["pageno"] - 1) * 10, "as_sdt": "2007", # include patents / to disable set "0,5" "as_vis": "0", # include citations / to disable set "1" } args.update(time_range_args(params)) params["url"] = "https://" + google_info["subdomain"] + "/scholar?" + urlencode(args) params["cookies"] = google_info["cookies"] params["headers"].update(google_info["headers"]) def response(resp: "SXNG_Response") -> EngineResults: # pylint: disable=too-many-locals """Parse response from Google Scholar""" if resp.status_code in (301, 302, 303, 307, 308) and "Location" in resp.headers: if "/sorry/index?continue" in resp.headers["Location"]: # Our systems have detected unusual traffic from your computer # network. Please try again later. raise SearxEngineAccessDeniedException( message="google_scholar: unusual traffic detected", ) raise httpx.TooManyRedirects(f"location {resp.headers['Location'].split('?')[0]}") res = EngineResults() dom = html.fromstring(resp.text) detect_google_captcha(dom) # parse results for result in eval_xpath_list(dom, "//div[@data-rp]"): title = extract_text(eval_xpath(result, ".//h3[1]//a")) if not title: # this is a [ZITATION] block continue pub_type: str = extract_text(eval_xpath(result, ".//span[@class='gs_ctg2']")) or "" if pub_type: pub_type = pub_type[1:-1].lower() url: str = eval_xpath_getindex(result, ".//h3[1]//a/@href", 0) content: str = extract_text(eval_xpath(result, ".//div[@class='gs_rs']")) or "" authors, journal, publisher, publishedDate = parse_gs_a( extract_text(eval_xpath(result, ".//div[@class='gs_a']")) ) if publisher in url: publisher = "" # cited by comments: str = ( extract_text(eval_xpath(result, ".//div[@class='gs_fl']/a[starts-with(@href,'/scholar?cites=')]")) or "" ) # link to the html or pdf document html_url: str = "" pdf_url: str = "" doc_url = eval_xpath_getindex(result, ".//div[@class='gs_or_ggsm']/a/@href", 0, default=None) doc_type = extract_text(eval_xpath(result, ".//span[@class='gs_ctg2']")) if doc_type == "[PDF]": pdf_url = doc_url else: html_url = doc_url res.add( res.types.Paper( type=pub_type, url=url, title=title, authors=authors, publisher=publisher, journal=journal, publishedDate=publishedDate, content=content, comments=comments, html_url=html_url, pdf_url=pdf_url, ) ) # parse suggestion for suggestion in eval_xpath(dom, "//div[contains(@class, 'gs_qsuggest_wrap')]//li//a"): res.add(res.types.LegacyResult(suggestion=extract_text(suggestion))) for correction in eval_xpath(dom, "//div[@class='gs_r gs_pda']/a"): res.add(res.types.LegacyResult(correction=extract_text(correction))) return res def time_range_args(params: "OnlineParams") -> dict[str, int]: """Returns a dictionary with a time range arguments based on ``params["time_range"]``. Google Scholar supports a detailed search by year. Searching by *last month* or *last week* (as offered by SearXNG) is uncommon for scientific publications and is not supported by Google Scholar. To limit the result list when the users selects a range, all the SearXNG ranges (*day*, *week*, *month*, *year*) are mapped to *year*. If no range is set an empty dictionary of arguments is returned. Example; when user selects a time range and we find ourselves in the year 2025 (current year minus one): .. code:: python { "as_ylo" : 2024 } """ ret_val: dict[str, int] = {} if params["time_range"] in time_range_dict: ret_val["as_ylo"] = datetime.now().year - 1 return ret_val def detect_google_captcha(dom: ElementType): """In case of CAPTCHA Google Scholar open its own *not a Robot* dialog and is not redirected to ``sorry.google.com``. """ if eval_xpath(dom, "//form[@id='gs_captcha_f']"): raise SearxEngineCaptchaException(message="CAPTCHA (gs_captcha_f)") def parse_gs_a(text: str | None) -> tuple[list[str], str, str, datetime | None]: """Parse the text written in green. Possible formats: * "{authors} - {journal}, {year} - {publisher}" * "{authors} - {year} - {publisher}" * "{authors} - {publisher}" """ if text is None or text == "": return [], "", "", None s_text = text.split(" - ") authors: list[str] = s_text[0].split(", ") publisher: str = s_text[-1] if len(s_text) != 3: return authors, "", publisher, None # the format is "{authors} - {journal}, {year} - {publisher}" or "{authors} - {year} - {publisher}" # get journal and year journal_year = s_text[1].split(", ") # journal is optional and may contains some coma if len(journal_year) > 1: journal: str = ", ".join(journal_year[0:-1]) if journal == "…": journal = "" else: journal = "" # year year = journal_year[-1] try: publishedDate = datetime.strptime(year.strip(), "%Y") except ValueError: publishedDate = None return authors, journal, publisher, publishedDate