[feat] engines: add europepmc (science, scientific publications)

docs/dev/engines/online/europepmc.rst

@@ -0,0 +1,8 @@
+.. _europepmc engine:
+
+==========
+Europe PMC
+==========
+
+.. automodule:: searx.engines.europepmc
+   :members:

searx/engines/europepmc.py

@@ -0,0 +1,150 @@
+# SPDX-License-Identifier: AGPL-3.0-or-later
+"""`Europe PMC`_ provides comprehensive access to life sciences literature from
+trusted sources.  With Europe PMC you can search and read millions of
+publications, preprints and other documents enriched with links to supporting
+data, reviews, protocols, and other relevant resources.
+
+.. _Europe PMC: https://europepmc.org/
+
+Configuration
+=============
+
+.. code:: yaml
+
+   - name: europepmc
+     engine: europepmc
+     shortcut: epmc
+
+Implementations
+===============
+
+"""
+
+import typing as t
+
+from datetime import datetime
+from urllib.parse import urlencode
+
+from dateutil.parser import isoparse
+
+from searx.enginelib import EngineCache
+from searx.result_types import EngineResults
+from searx.utils import html_to_text
+
+if t.TYPE_CHECKING:
+    from searx.extended_types import SXNG_Response
+    from searx.search.processors import OnlineParams
+
+
+about = {
+    "website": "https://europepmc.org/",
+    "wikidata_id": "Q5412157",
+    "official_api_documentation": "https://europepmc.org/RestfulWebService",
+    "use_official_api": True,
+    "require_api_key": False,
+    "results": "JSON",
+}
+
+categories = ["science", "scientific publications"]
+paging = True
+
+# engine dependent config
+search_url = "https://www.ebi.ac.uk/europepmc/webservices/rest/search"
+article_url = "https://europepmc.org/article/"
+
+page_size = 20
+
+CACHE: EngineCache
+"""Cache for storing the pagination cursor."""
+
+
+def setup(engine_settings: dict[str, t.Any]):
+    global CACHE  # pylint: disable=global-statement
+    CACHE = EngineCache(engine_settings["name"])
+
+
+def _cache_key(query: str, page: int) -> str:
+    return f"{query}|{page}"
+
+
+def request(query: str, params: "OnlineParams") -> None:
+    args = {
+        "query": query,
+        "format": "json",
+        "resultType": "core",
+        "pageSize": page_size,
+    }
+
+    if params["pageno"] > 1:
+        if cursor := CACHE.get(_cache_key(query, params["pageno"])):
+            args["cursorMark"] = cursor
+        else:
+            # no cached cursor for that page
+            params["url"] = None
+            return
+
+    params["url"] = f"{search_url}?{urlencode(args)}"
+
+
+def response(resp: "SXNG_Response") -> EngineResults:
+    res = EngineResults()
+
+    json_resp = resp.json()
+
+    # store pagination cursor for loading next pages in cache
+    if next_cursor := json_resp.get("nextCursorMark"):
+        next_page = resp.search_params["pageno"] + 1
+        query = resp.search_params["query"]
+        CACHE.set(_cache_key(query, next_page), next_cursor)
+
+    all_results = json_resp.get("resultList", {}).get("result", [])
+
+    for item in all_results:
+        source = item.get("source", "")
+        identifier = item.get("id", "")
+        url = f"{article_url}{source}/{identifier}" if source and identifier else ""
+
+        journal_info: dict[str, t.Any] = item.get("journalInfo", {})
+        journal: dict[str, t.Any] = journal_info.get("journal", {})
+
+        res.add(
+            res.types.Paper(
+                url=url,
+                title=html_to_text(item.get("title", "")),
+                content=html_to_text(item.get("abstractText", "")),
+                journal=journal.get("title", ""),
+                issn=[journal.get("issn", "")],
+                authors=_get_authors(item),
+                doi=item.get("doi", ""),
+                publishedDate=_get_published_date(item),
+                type=", ".join((item.get("pubTypeList", {})).get("pubType", [])),
+                pdf_url=_get_pdf_url(item),
+                html_url=url,
+            )
+        )
+
+    return res
+
+
+def _get_authors(item: dict[str, t.Any]) -> list:
+    """Extract the list of authors from the item."""
+    if authors := item.get("authorString", None):
+        authors = [author.strip().rstrip(".") for author in authors.split(",") if author.strip()]
+    else:
+        authors = []
+    return authors
+
+
+def _get_pdf_url(item: dict[str, t.Any]) -> str:
+    """Extract the PDF URL in case it is open access."""
+    for url_info in (item.get("fullTextUrlList", {})).get("fullTextUrl", []):
+        if url_info.get("documentStyle") == "pdf" and url_info.get("availabilityCode") == "OA":
+            return url_info.get("url", "")
+    return ""
+
+
+def _get_published_date(item: dict[str, t.Any]) -> datetime | None:
+    """Extract the published date from the item and convert it to a datetime object."""
+    if unformatted_date := item.get("firstPublicationDate"):
+        return isoparse(unformatted_date)
+    return None

searx/settings.yml

@@ -792,6 +792,10 @@ engines:
       require_api_key: false
       results: JSON
 
+  - name: europepmc
+    engine: europepmc
+    shortcut: epmc
+
   - name: erowid
     engine: xpath
     paging: true