New TGRM search implementation

fastapi_book_server/app/services/common.py

@@ -1,7 +1,5 @@
 from typing import Optional, Generic, TypeVar, Union
-from itertools import permutations
 from databases import Database
-import json
 
 from fastapi_pagination.api import resolve_params
 from fastapi_pagination.bases import AbstractParams, RawParams
@@ -10,17 +8,7 @@ import aioredis
 import orjson
 
 from ormar import Model, QuerySet
-from sqlalchemy import text, func, select, or_, Table, Column, cast, Text
-from sqlalchemy.orm import Session
-
-
-def join_fields(fields):
-    result = fields[0]
-
-    for el in fields[1:]:
-        result += text("' '") + el
-
-    return result
+from sqlalchemy import Table
 
 
 T = TypeVar('T', bound=Model)
@@ -28,10 +16,9 @@ T = TypeVar('T', bound=Model)
 
 class TRGMSearchService(Generic[T]):
     MODEL_CLASS: Optional[T] = None
-    FIELDS: Optional[list[Column]] = None
     SELECT_RELATED: Optional[Union[list[str], str]] = None
     PREFETCH_RELATED: Optional[Union[list[str], str]] = None
-    FILTERS = []
+    GET_OBJECT_IDS_QUERY: Optional[str] = None
     CACHE_TTL = 5 * 60
 
     @classmethod
@@ -60,52 +47,18 @@ class TRGMSearchService(Generic[T]):
 
     @classmethod
     @property
-    def fields_combinations(cls):
-        assert cls.FIELDS is not None, f"FIELDS in {cls.__name__} don't set!"
-        assert len(cls.FIELDS) != 0, f"FIELDS in {cls.__name__} must be not empty!"
-
-        return permutations(cls.FIELDS, len(cls.FIELDS))
-
-    @classmethod
-    def get_similarity_subquery(cls, query: str):
-        combs = cls.fields_combinations
-
-        return func.greatest(
-            *[func.similarity(join_fields(comb), cast(query, Text)) for comb in combs]
-        ).label("sml")
-
-    @classmethod
-    def get_similarity_filter_subquery(cls, query: str):
-        return or_(
-            *[join_fields(comb) % f"{query}::text" for comb in cls.fields_combinations]
-        )
+    def object_ids_query(cls) -> str:
+        assert cls.GET_OBJECT_IDS_QUERY is not None, f"GET_OBJECT_IDS_QUERY in {cls.__name__} don't set!"
+        return cls.GET_OBJECT_IDS_QUERY
 
     @classmethod
     async def _get_object_ids(cls, query_data: str) -> list[int]:
-        similarity = cls.get_similarity_subquery(query_data)
-        similarity_filter = cls.get_similarity_filter_subquery(query_data)
-
-        session = Session(cls.database.connection())
-
-        filtered_objects_query = session.query(
-            cls.table.c.id, similarity
-        ).order_by(
-            text('sml DESC')
-        ).filter(
-            similarity_filter,
-            *cls.FILTERS
-        ).cte('objs')
-
-        object_ids_query = session.query(
-            func.array_agg(filtered_objects_query.c.id)
-        ).cte()
-
-        row = await cls.database.fetch_one(object_ids_query)
+        row = await cls.database.fetch_one(cls.object_ids_query, {"query": query_data})
 
         if row is None:
             raise ValueError('Something is wrong!')
 
-        return row['array_agg_1']
+        return row['array']
 
     @classmethod
     def get_cache_key(cls, query_data: str) -> str: