anonymousland-synapse/synapse/storage/databases/main/user_directory.py

898 lines
32 KiB
Python

# Copyright 2017 Vector Creations Ltd
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import logging
import re
from typing import (
TYPE_CHECKING,
Dict,
Iterable,
List,
Optional,
Sequence,
Set,
Tuple,
cast,
)
if TYPE_CHECKING:
from synapse.server import HomeServer
from synapse.api.constants import EventTypes, HistoryVisibility, JoinRules
from synapse.storage.database import DatabasePool, LoggingTransaction
from synapse.storage.databases.main.state import StateFilter
from synapse.storage.databases.main.state_deltas import StateDeltasStore
from synapse.storage.engines import PostgresEngine, Sqlite3Engine
from synapse.storage.types import Connection
from synapse.types import JsonDict, get_domain_from_id, get_localpart_from_id
from synapse.util.caches.descriptors import cached
logger = logging.getLogger(__name__)
TEMP_TABLE = "_temp_populate_user_directory"
class UserDirectoryBackgroundUpdateStore(StateDeltasStore):
# How many records do we calculate before sending it to
# add_users_who_share_private_rooms?
SHARE_PRIVATE_WORKING_SET = 500
def __init__(
self,
database: DatabasePool,
db_conn: Connection,
hs: "HomeServer",
):
super().__init__(database, db_conn, hs)
self.server_name = hs.hostname
self.db_pool.updates.register_background_update_handler(
"populate_user_directory_createtables",
self._populate_user_directory_createtables,
)
self.db_pool.updates.register_background_update_handler(
"populate_user_directory_process_rooms",
self._populate_user_directory_process_rooms,
)
self.db_pool.updates.register_background_update_handler(
"populate_user_directory_process_users",
self._populate_user_directory_process_users,
)
self.db_pool.updates.register_background_update_handler(
"populate_user_directory_cleanup", self._populate_user_directory_cleanup
)
async def _populate_user_directory_createtables(
self, progress: JsonDict, batch_size: int
) -> int:
# Get all the rooms that we want to process.
def _make_staging_area(txn: LoggingTransaction) -> None:
sql = (
"CREATE TABLE IF NOT EXISTS "
+ TEMP_TABLE
+ "_rooms(room_id TEXT NOT NULL, events BIGINT NOT NULL)"
)
txn.execute(sql)
sql = (
"CREATE TABLE IF NOT EXISTS "
+ TEMP_TABLE
+ "_position(position TEXT NOT NULL)"
)
txn.execute(sql)
# Get rooms we want to process from the database
sql = """
SELECT room_id, count(*) FROM current_state_events
GROUP BY room_id
"""
txn.execute(sql)
rooms = [{"room_id": x[0], "events": x[1]} for x in txn.fetchall()]
self.db_pool.simple_insert_many_txn(txn, TEMP_TABLE + "_rooms", rooms)
del rooms
sql = (
"CREATE TABLE IF NOT EXISTS "
+ TEMP_TABLE
+ "_users(user_id TEXT NOT NULL)"
)
txn.execute(sql)
txn.execute("SELECT name FROM users")
users = [{"user_id": x[0]} for x in txn.fetchall()]
self.db_pool.simple_insert_many_txn(txn, TEMP_TABLE + "_users", users)
new_pos = await self.get_max_stream_id_in_current_state_deltas()
await self.db_pool.runInteraction(
"populate_user_directory_temp_build", _make_staging_area
)
await self.db_pool.simple_insert(
TEMP_TABLE + "_position", {"position": new_pos}
)
await self.db_pool.updates._end_background_update(
"populate_user_directory_createtables"
)
return 1
async def _populate_user_directory_cleanup(
self,
progress: JsonDict,
batch_size: int,
) -> int:
"""
Update the user directory stream position, then clean up the old tables.
"""
position = await self.db_pool.simple_select_one_onecol(
TEMP_TABLE + "_position", {}, "position"
)
await self.update_user_directory_stream_pos(position)
def _delete_staging_area(txn: LoggingTransaction) -> None:
txn.execute("DROP TABLE IF EXISTS " + TEMP_TABLE + "_rooms")
txn.execute("DROP TABLE IF EXISTS " + TEMP_TABLE + "_users")
txn.execute("DROP TABLE IF EXISTS " + TEMP_TABLE + "_position")
await self.db_pool.runInteraction(
"populate_user_directory_cleanup", _delete_staging_area
)
await self.db_pool.updates._end_background_update(
"populate_user_directory_cleanup"
)
return 1
async def _populate_user_directory_process_rooms(
self, progress: JsonDict, batch_size: int
) -> int:
"""
Rescan the state of all rooms so we can track
- who's in a public room;
- which local users share a private room with other users (local
and remote); and
- who should be in the user_directory.
Args:
progress (dict)
batch_size (int): Maximum number of state events to process
per cycle.
Returns:
number of events processed.
"""
# If we don't have progress filed, delete everything.
if not progress:
await self.delete_all_from_user_dir()
def _get_next_batch(
txn: LoggingTransaction,
) -> Optional[Sequence[Tuple[str, int]]]:
# Only fetch 250 rooms, so we don't fetch too many at once, even
# if those 250 rooms have less than batch_size state events.
sql = """
SELECT room_id, events FROM %s
ORDER BY events DESC
LIMIT 250
""" % (
TEMP_TABLE + "_rooms",
)
txn.execute(sql)
rooms_to_work_on = cast(List[Tuple[str, int]], txn.fetchall())
if not rooms_to_work_on:
return None
# Get how many are left to process, so we can give status on how
# far we are in processing
txn.execute("SELECT COUNT(*) FROM " + TEMP_TABLE + "_rooms")
result = txn.fetchone()
assert result is not None
progress["remaining"] = result[0]
return rooms_to_work_on
rooms_to_work_on = await self.db_pool.runInteraction(
"populate_user_directory_temp_read", _get_next_batch
)
# No more rooms -- complete the transaction.
if not rooms_to_work_on:
await self.db_pool.updates._end_background_update(
"populate_user_directory_process_rooms"
)
return 1
logger.debug(
"Processing the next %d rooms of %d remaining"
% (len(rooms_to_work_on), progress["remaining"])
)
processed_event_count = 0
for room_id, event_count in rooms_to_work_on:
is_in_room = await self.is_host_joined(room_id, self.server_name)
if is_in_room:
is_public = await self.is_room_world_readable_or_publicly_joinable(
room_id
)
users_with_profile = await self.get_users_in_room_with_profiles(room_id)
# Update each user in the user directory.
for user_id, profile in users_with_profile.items():
await self.update_profile_in_user_dir(
user_id, profile.display_name, profile.avatar_url
)
to_insert = set()
if is_public:
for user_id in users_with_profile:
if self.get_if_app_services_interested_in_user(user_id):
continue
to_insert.add(user_id)
if to_insert:
await self.add_users_in_public_rooms(room_id, to_insert)
to_insert.clear()
else:
for user_id in users_with_profile:
if not self.hs.is_mine_id(user_id):
continue
if self.get_if_app_services_interested_in_user(user_id):
continue
for other_user_id in users_with_profile:
if user_id == other_user_id:
continue
user_set = (user_id, other_user_id)
to_insert.add(user_set)
# If it gets too big, stop and write to the database
# to prevent storing too much in RAM.
if len(to_insert) >= self.SHARE_PRIVATE_WORKING_SET:
await self.add_users_who_share_private_room(
room_id, to_insert
)
to_insert.clear()
if to_insert:
await self.add_users_who_share_private_room(room_id, to_insert)
to_insert.clear()
# We've finished a room. Delete it from the table.
await self.db_pool.simple_delete_one(
TEMP_TABLE + "_rooms", {"room_id": room_id}
)
# Update the remaining counter.
progress["remaining"] -= 1
await self.db_pool.runInteraction(
"populate_user_directory",
self.db_pool.updates._background_update_progress_txn,
"populate_user_directory_process_rooms",
progress,
)
processed_event_count += event_count
if processed_event_count > batch_size:
# Don't process any more rooms, we've hit our batch size.
return processed_event_count
return processed_event_count
async def _populate_user_directory_process_users(
self, progress: JsonDict, batch_size: int
) -> int:
"""
Add all local users to the user directory.
"""
def _get_next_batch(txn: LoggingTransaction) -> Optional[List[str]]:
sql = "SELECT user_id FROM %s LIMIT %s" % (
TEMP_TABLE + "_users",
str(batch_size),
)
txn.execute(sql)
user_result = cast(List[Tuple[str]], txn.fetchall())
if not user_result:
return None
users_to_work_on = [x[0] for x in user_result]
# Get how many are left to process, so we can give status on how
# far we are in processing
sql = "SELECT COUNT(*) FROM " + TEMP_TABLE + "_users"
txn.execute(sql)
count_result = txn.fetchone()
assert count_result is not None
progress["remaining"] = count_result[0]
return users_to_work_on
users_to_work_on = await self.db_pool.runInteraction(
"populate_user_directory_temp_read", _get_next_batch
)
# No more users -- complete the transaction.
if not users_to_work_on:
await self.db_pool.updates._end_background_update(
"populate_user_directory_process_users"
)
return 1
logger.debug(
"Processing the next %d users of %d remaining"
% (len(users_to_work_on), progress["remaining"])
)
for user_id in users_to_work_on:
profile = await self.get_profileinfo(get_localpart_from_id(user_id))
await self.update_profile_in_user_dir(
user_id, profile.display_name, profile.avatar_url
)
# We've finished processing a user. Delete it from the table.
await self.db_pool.simple_delete_one(
TEMP_TABLE + "_users", {"user_id": user_id}
)
# Update the remaining counter.
progress["remaining"] -= 1
await self.db_pool.runInteraction(
"populate_user_directory",
self.db_pool.updates._background_update_progress_txn,
"populate_user_directory_process_users",
progress,
)
return len(users_to_work_on)
async def is_room_world_readable_or_publicly_joinable(self, room_id: str) -> bool:
"""Check if the room is either world_readable or publically joinable"""
# Create a state filter that only queries join and history state event
types_to_filter = (
(EventTypes.JoinRules, ""),
(EventTypes.RoomHistoryVisibility, ""),
)
current_state_ids = await self.get_filtered_current_state_ids(
room_id, StateFilter.from_types(types_to_filter)
)
join_rules_id = current_state_ids.get((EventTypes.JoinRules, ""))
if join_rules_id:
join_rule_ev = await self.get_event(join_rules_id, allow_none=True)
if join_rule_ev:
if join_rule_ev.content.get("join_rule") == JoinRules.PUBLIC:
return True
hist_vis_id = current_state_ids.get((EventTypes.RoomHistoryVisibility, ""))
if hist_vis_id:
hist_vis_ev = await self.get_event(hist_vis_id, allow_none=True)
if hist_vis_ev:
if (
hist_vis_ev.content.get("history_visibility")
== HistoryVisibility.WORLD_READABLE
):
return True
return False
async def update_profile_in_user_dir(
self, user_id: str, display_name: Optional[str], avatar_url: Optional[str]
) -> None:
"""
Update or add a user's profile in the user directory.
"""
# If the display name or avatar URL are unexpected types, overwrite them.
if not isinstance(display_name, str):
display_name = None
if not isinstance(avatar_url, str):
avatar_url = None
def _update_profile_in_user_dir_txn(txn: LoggingTransaction) -> None:
self.db_pool.simple_upsert_txn(
txn,
table="user_directory",
keyvalues={"user_id": user_id},
values={"display_name": display_name, "avatar_url": avatar_url},
lock=False, # We're only inserter
)
if isinstance(self.database_engine, PostgresEngine):
# We weight the localpart most highly, then display name and finally
# server name
sql = """
INSERT INTO user_directory_search(user_id, vector)
VALUES (?,
setweight(to_tsvector('simple', ?), 'A')
|| setweight(to_tsvector('simple', ?), 'D')
|| setweight(to_tsvector('simple', COALESCE(?, '')), 'B')
) ON CONFLICT (user_id) DO UPDATE SET vector=EXCLUDED.vector
"""
txn.execute(
sql,
(
user_id,
get_localpart_from_id(user_id),
get_domain_from_id(user_id),
display_name,
),
)
elif isinstance(self.database_engine, Sqlite3Engine):
value = "%s %s" % (user_id, display_name) if display_name else user_id
self.db_pool.simple_upsert_txn(
txn,
table="user_directory_search",
keyvalues={"user_id": user_id},
values={"value": value},
lock=False, # We're only inserter
)
else:
# This should be unreachable.
raise Exception("Unrecognized database engine")
txn.call_after(self.get_user_in_directory.invalidate, (user_id,))
await self.db_pool.runInteraction(
"update_profile_in_user_dir", _update_profile_in_user_dir_txn
)
async def add_users_who_share_private_room(
self, room_id: str, user_id_tuples: Iterable[Tuple[str, str]]
) -> None:
"""Insert entries into the users_who_share_private_rooms table. The first
user should be a local user.
Args:
room_id
user_id_tuples: iterable of 2-tuple of user IDs.
"""
await self.db_pool.simple_upsert_many(
table="users_who_share_private_rooms",
key_names=["user_id", "other_user_id", "room_id"],
key_values=[
(user_id, other_user_id, room_id)
for user_id, other_user_id in user_id_tuples
],
value_names=(),
value_values=(),
desc="add_users_who_share_room",
)
async def add_users_in_public_rooms(
self, room_id: str, user_ids: Iterable[str]
) -> None:
"""Insert entries into the users_in_public_rooms table.
Args:
room_id
user_ids
"""
await self.db_pool.simple_upsert_many(
table="users_in_public_rooms",
key_names=["user_id", "room_id"],
key_values=[(user_id, room_id) for user_id in user_ids],
value_names=(),
value_values=(),
desc="add_users_in_public_rooms",
)
async def delete_all_from_user_dir(self) -> None:
"""Delete the entire user directory"""
def _delete_all_from_user_dir_txn(txn: LoggingTransaction) -> None:
txn.execute("DELETE FROM user_directory")
txn.execute("DELETE FROM user_directory_search")
txn.execute("DELETE FROM users_in_public_rooms")
txn.execute("DELETE FROM users_who_share_private_rooms")
txn.call_after(self.get_user_in_directory.invalidate_all)
await self.db_pool.runInteraction(
"delete_all_from_user_dir", _delete_all_from_user_dir_txn
)
@cached()
async def get_user_in_directory(self, user_id: str) -> Optional[Dict[str, str]]:
return await self.db_pool.simple_select_one(
table="user_directory",
keyvalues={"user_id": user_id},
retcols=("display_name", "avatar_url"),
allow_none=True,
desc="get_user_in_directory",
)
async def update_user_directory_stream_pos(self, stream_id: int) -> None:
await self.db_pool.simple_update_one(
table="user_directory_stream_pos",
keyvalues={},
updatevalues={"stream_id": stream_id},
desc="update_user_directory_stream_pos",
)
class UserDirectoryStore(UserDirectoryBackgroundUpdateStore):
# How many records do we calculate before sending it to
# add_users_who_share_private_rooms?
SHARE_PRIVATE_WORKING_SET = 500
def __init__(
self,
database: DatabasePool,
db_conn: Connection,
hs: "HomeServer",
) -> None:
super().__init__(database, db_conn, hs)
self._prefer_local_users_in_search = (
hs.config.userdirectory.user_directory_search_prefer_local_users
)
self._server_name = hs.config.server.server_name
async def remove_from_user_dir(self, user_id: str) -> None:
def _remove_from_user_dir_txn(txn: LoggingTransaction) -> None:
self.db_pool.simple_delete_txn(
txn, table="user_directory", keyvalues={"user_id": user_id}
)
self.db_pool.simple_delete_txn(
txn, table="user_directory_search", keyvalues={"user_id": user_id}
)
self.db_pool.simple_delete_txn(
txn, table="users_in_public_rooms", keyvalues={"user_id": user_id}
)
self.db_pool.simple_delete_txn(
txn,
table="users_who_share_private_rooms",
keyvalues={"user_id": user_id},
)
self.db_pool.simple_delete_txn(
txn,
table="users_who_share_private_rooms",
keyvalues={"other_user_id": user_id},
)
txn.call_after(self.get_user_in_directory.invalidate, (user_id,))
await self.db_pool.runInteraction(
"remove_from_user_dir", _remove_from_user_dir_txn
)
async def get_users_in_dir_due_to_room(self, room_id: str) -> Set[str]:
"""Get all user_ids that are in the room directory because they're
in the given room_id
"""
user_ids_share_pub = await self.db_pool.simple_select_onecol(
table="users_in_public_rooms",
keyvalues={"room_id": room_id},
retcol="user_id",
desc="get_users_in_dir_due_to_room",
)
user_ids_share_priv = await self.db_pool.simple_select_onecol(
table="users_who_share_private_rooms",
keyvalues={"room_id": room_id},
retcol="other_user_id",
desc="get_users_in_dir_due_to_room",
)
user_ids = set(user_ids_share_pub)
user_ids.update(user_ids_share_priv)
return user_ids
async def remove_user_who_share_room(self, user_id: str, room_id: str) -> None:
"""
Deletes entries in the users_who_share_*_rooms table. The first
user should be a local user.
Args:
user_id
room_id
"""
def _remove_user_who_share_room_txn(txn: LoggingTransaction) -> None:
self.db_pool.simple_delete_txn(
txn,
table="users_who_share_private_rooms",
keyvalues={"user_id": user_id, "room_id": room_id},
)
self.db_pool.simple_delete_txn(
txn,
table="users_who_share_private_rooms",
keyvalues={"other_user_id": user_id, "room_id": room_id},
)
self.db_pool.simple_delete_txn(
txn,
table="users_in_public_rooms",
keyvalues={"user_id": user_id, "room_id": room_id},
)
await self.db_pool.runInteraction(
"remove_user_who_share_room", _remove_user_who_share_room_txn
)
async def get_user_dir_rooms_user_is_in(self, user_id: str) -> List[str]:
"""
Returns the rooms that a user is in.
Args:
user_id(str): Must be a local user
Returns:
list: user_id
"""
rows = await self.db_pool.simple_select_onecol(
table="users_who_share_private_rooms",
keyvalues={"user_id": user_id},
retcol="room_id",
desc="get_rooms_user_is_in",
)
pub_rows = await self.db_pool.simple_select_onecol(
table="users_in_public_rooms",
keyvalues={"user_id": user_id},
retcol="room_id",
desc="get_rooms_user_is_in",
)
users = set(pub_rows)
users.update(rows)
return list(users)
async def get_shared_rooms_for_users(
self, user_id: str, other_user_id: str
) -> Set[str]:
"""
Returns the rooms that a local user shares with another local or remote user.
Args:
user_id: The MXID of a local user
other_user_id: The MXID of the other user
Returns:
A set of room ID's that the users share.
"""
def _get_shared_rooms_for_users_txn(
txn: LoggingTransaction,
) -> List[Dict[str, str]]:
txn.execute(
"""
SELECT p1.room_id
FROM users_in_public_rooms as p1
INNER JOIN users_in_public_rooms as p2
ON p1.room_id = p2.room_id
AND p1.user_id = ?
AND p2.user_id = ?
UNION
SELECT room_id
FROM users_who_share_private_rooms
WHERE
user_id = ?
AND other_user_id = ?
""",
(user_id, other_user_id, user_id, other_user_id),
)
rows = self.db_pool.cursor_to_dict(txn)
return rows
rows = await self.db_pool.runInteraction(
"get_shared_rooms_for_users", _get_shared_rooms_for_users_txn
)
return {row["room_id"] for row in rows}
async def get_user_directory_stream_pos(self) -> Optional[int]:
"""
Get the stream ID of the user directory stream.
Returns:
The stream token or None if the initial background update hasn't happened yet.
"""
return await self.db_pool.simple_select_one_onecol(
table="user_directory_stream_pos",
keyvalues={},
retcol="stream_id",
desc="get_user_directory_stream_pos",
)
async def search_user_dir(
self, user_id: str, search_term: str, limit: int
) -> JsonDict:
"""Searches for users in directory
Returns:
dict of the form::
{
"limited": <bool>, # whether there were more results or not
"results": [ # Ordered by best match first
{
"user_id": <user_id>,
"display_name": <display_name>,
"avatar_url": <avatar_url>
}
]
}
"""
if self.hs.config.userdirectory.user_directory_search_all_users:
join_args = (user_id,)
where_clause = "user_id != ?"
else:
join_args = (user_id,)
where_clause = """
(
EXISTS (select 1 from users_in_public_rooms WHERE user_id = t.user_id)
OR EXISTS (
SELECT 1 FROM users_who_share_private_rooms
WHERE user_id = ? AND other_user_id = t.user_id
)
)
"""
# We allow manipulating the ranking algorithm by injecting statements
# based on config options.
additional_ordering_statements = []
ordering_arguments: Tuple[str, ...] = ()
if isinstance(self.database_engine, PostgresEngine):
full_query, exact_query, prefix_query = _parse_query_postgres(search_term)
# If enabled, this config option will rank local users higher than those on
# remote instances.
if self._prefer_local_users_in_search:
# This statement checks whether a given user's user ID contains a server name
# that matches the local server
statement = "* (CASE WHEN user_id LIKE ? THEN 2.0 ELSE 1.0 END)"
additional_ordering_statements.append(statement)
ordering_arguments += ("%:" + self._server_name,)
# We order by rank and then if they have profile info
# The ranking algorithm is hand tweaked for "best" results. Broadly
# the idea is we give a higher weight to exact matches.
# The array of numbers are the weights for the various part of the
# search: (domain, _, display name, localpart)
sql = """
SELECT d.user_id AS user_id, display_name, avatar_url
FROM user_directory_search as t
INNER JOIN user_directory AS d USING (user_id)
WHERE
%(where_clause)s
AND vector @@ to_tsquery('simple', ?)
ORDER BY
(CASE WHEN d.user_id IS NOT NULL THEN 4.0 ELSE 1.0 END)
* (CASE WHEN display_name IS NOT NULL THEN 1.2 ELSE 1.0 END)
* (CASE WHEN avatar_url IS NOT NULL THEN 1.2 ELSE 1.0 END)
* (
3 * ts_rank_cd(
'{0.1, 0.1, 0.9, 1.0}',
vector,
to_tsquery('simple', ?),
8
)
+ ts_rank_cd(
'{0.1, 0.1, 0.9, 1.0}',
vector,
to_tsquery('simple', ?),
8
)
)
%(order_case_statements)s
DESC,
display_name IS NULL,
avatar_url IS NULL
LIMIT ?
""" % {
"where_clause": where_clause,
"order_case_statements": " ".join(additional_ordering_statements),
}
args = (
join_args
+ (full_query, exact_query, prefix_query)
+ ordering_arguments
+ (limit + 1,)
)
elif isinstance(self.database_engine, Sqlite3Engine):
search_query = _parse_query_sqlite(search_term)
# If enabled, this config option will rank local users higher than those on
# remote instances.
if self._prefer_local_users_in_search:
# This statement checks whether a given user's user ID contains a server name
# that matches the local server
#
# Note that we need to include a comma at the end for valid SQL
statement = "user_id LIKE ? DESC,"
additional_ordering_statements.append(statement)
ordering_arguments += ("%:" + self._server_name,)
sql = """
SELECT d.user_id AS user_id, display_name, avatar_url
FROM user_directory_search as t
INNER JOIN user_directory AS d USING (user_id)
WHERE
%(where_clause)s
AND value MATCH ?
ORDER BY
rank(matchinfo(user_directory_search)) DESC,
%(order_statements)s
display_name IS NULL,
avatar_url IS NULL
LIMIT ?
""" % {
"where_clause": where_clause,
"order_statements": " ".join(additional_ordering_statements),
}
args = join_args + (search_query,) + ordering_arguments + (limit + 1,)
else:
# This should be unreachable.
raise Exception("Unrecognized database engine")
results = await self.db_pool.execute(
"search_user_dir", self.db_pool.cursor_to_dict, sql, *args
)
limited = len(results) > limit
return {"limited": limited, "results": results}
def _parse_query_sqlite(search_term: str) -> str:
"""Takes a plain unicode string from the user and converts it into a form
that can be passed to database.
We use this so that we can add prefix matching, which isn't something
that is supported by default.
We specifically add both a prefix and non prefix matching term so that
exact matches get ranked higher.
"""
# Pull out the individual words, discarding any non-word characters.
results = re.findall(r"([\w\-]+)", search_term, re.UNICODE)
return " & ".join("(%s* OR %s)" % (result, result) for result in results)
def _parse_query_postgres(search_term: str) -> Tuple[str, str, str]:
"""Takes a plain unicode string from the user and converts it into a form
that can be passed to database.
We use this so that we can add prefix matching, which isn't something
that is supported by default.
"""
# Pull out the individual words, discarding any non-word characters.
results = re.findall(r"([\w\-]+)", search_term, re.UNICODE)
both = " & ".join("(%s:* | %s)" % (result, result) for result in results)
exact = " & ".join("%s" % (result,) for result in results)
prefix = " & ".join("%s:*" % (result,) for result in results)
return both, exact, prefix