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searx/engines/sqlite.py

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+# SPDX-License-Identifier: AGPL-3.0-or-later
+"""SQLite is a small, fast and reliable SQL database engine.  It does not require
+any extra dependency.
+
+Configuration
+=============
+
+The engine has the following (additional) settings:
+
+- :py:obj:`result_type`
+
+
+Example
+=======
+
+.. _MediathekView: https://mediathekview.de/
+
+To demonstrate the power of database engines, here is a more complex example
+which reads from a MediathekView_ (DE) movie database.  For this example of the
+SQLite engine download the database:
+
+- https://liste.mediathekview.de/filmliste-v2.db.bz2
+
+and unpack into ``searx/data/filmliste-v2.db``.  To search the database use e.g
+Query to test: ``!mediathekview concert``
+
+.. code:: yaml
+
+  - name: mediathekview
+    engine: sqlite
+    shortcut: mediathekview
+    categories: [general, videos]
+    result_type: MainResult
+    database: searx/data/filmliste-v2.db
+    query_str: >-
+      SELECT title || ' (' || time(duration, 'unixepoch') || ')' AS title,
+             COALESCE( NULLIF(url_video_hd,''), NULLIF(url_video_sd,''), url_video) AS url,
+             description AS content
+        FROM film
+       WHERE title LIKE :wildcard OR description LIKE :wildcard
+       ORDER BY duration DESC
+
+Implementations
+===============
+
+"""
+import typing
+import sqlite3
+import contextlib
+
+from searx.result_types import EngineResults
+from searx.result_types import MainResult, KeyValue
+
+engine_type = "offline"
+
+database = ""
+"""Filename of the SQLite DB."""
+
+query_str = ""
+"""SQL query that returns the result items."""
+
+result_type: typing.Literal["MainResult", "KeyValue"] = "KeyValue"
+"""The result type can be :py:obj:`MainResult` or :py:obj:`KeyValue`."""
+
+limit = 10
+paging = True
+
+
+def init(engine_settings):
+    if 'query_str' not in engine_settings:
+        raise ValueError('query_str cannot be empty')
+
+    if not engine_settings['query_str'].lower().startswith('select '):
+        raise ValueError('only SELECT query is supported')
+
+
+@contextlib.contextmanager
+def sqlite_cursor():
+    """Implements a :py:obj:`Context Manager <contextlib.contextmanager>` for a
+    :py:obj:`sqlite3.Cursor`.
+
+    Open database in read only mode: if the database doesn't exist.  The default
+    mode creates an empty file on the file system.  See:
+
+    * https://docs.python.org/3/library/sqlite3.html#sqlite3.connect
+    * https://www.sqlite.org/uri.html
+
+    """
+    uri = 'file:' + database + '?mode=ro'
+    with contextlib.closing(sqlite3.connect(uri, uri=True)) as connect:
+        connect.row_factory = sqlite3.Row
+        with contextlib.closing(connect.cursor()) as cursor:
+            yield cursor
+
+
+def search(query, params) -> EngineResults:
+    res = EngineResults()
+    query_params = {
+        'query': query,
+        'wildcard': r'%' + query.replace(' ', r'%') + r'%',
+        'limit': limit,
+        'offset': (params['pageno'] - 1) * limit,
+    }
+    query_to_run = query_str + ' LIMIT :limit OFFSET :offset'
+
+    with sqlite_cursor() as cur:
+
+        cur.execute(query_to_run, query_params)
+        col_names = [cn[0] for cn in cur.description]
+
+        for row in cur.fetchall():
+            kvmap = dict(zip(col_names, map(str, row)))
+            if result_type == "MainResult":
+                item = MainResult(**kvmap)  # type: ignore
+            else:
+                item = KeyValue(kvmap=kvmap)
+            res.add(item)
+
+    return res