Update random objects getter

fastapi_book_server/app/services/author.py

@@ -1,6 +1,6 @@
 from app.models import Author
 
-from app.services.common import TRGMSearchService
+from app.services.common import TRGMSearchService, GetRandomService
 
 
 GET_OBJECT_IDS_QUERY = """
@@ -41,3 +41,7 @@ class AuthorTGRMSearchService(TRGMSearchService):
     MODEL_CLASS = Author
     PREFETCH_RELATED = ["source", "annotations"]
     GET_OBJECT_IDS_QUERY = GET_OBJECT_IDS_QUERY
+
+
+class GetRandomAuthorService(GetRandomService):
+    MODEL_CLASS = Author

fastapi_book_server/app/services/book.py

@@ -4,7 +4,7 @@ from fastapi import HTTPException, status
 
 from app.models import Book as BookDB, Author as AuthorDB
 
-from app.services.common import TRGMSearchService
+from app.services.common import TRGMSearchService, GetRandomService
 from app.serializers.book import CreateBook, CreateRemoteBook
 
 
@@ -76,3 +76,7 @@ class BookCreator:
             return await cls._create_book(data)
         if isinstance(data, CreateRemoteBook):
             return await cls._create_remote_book(data)
+
+
+class GetRandomBookService(GetRandomService):
+    MODEL_CLASS = BookDB

fastapi_book_server/app/services/common.py

@@ -122,3 +122,31 @@ class TRGMSearchService(Generic[T]):
             total=total,
             params=params
         )
+
+
+GET_RANDOM_OBJECT_ID_QUERY = """
+SELECT id FROM {table}
+WHERE id >= RANDOM() * (SELECT MAX(id) FROM {table})
+ORDER BY id LIMIT 1;
+"""
+
+
+class GetRandomService(Generic[T]):
+    MODEL_CLASS: Optional[T] = None
+
+    @classmethod
+    @property
+    def model(cls) -> T:
+        assert cls.MODEL_CLASS is not None, f"MODEL in {cls.__name__} don't set!"
+        return cls.MODEL_CLASS
+
+    @classmethod
+    @property
+    def database(cls) -> Database:
+        return cls.model.Meta.database
+
+    @classmethod
+    async def get_random_id(cls) -> int:
+        table_name = cls.model.Meta.tablename
+        query = GET_RANDOM_OBJECT_ID_QUERY.format(table=table_name)
+        return await cls.database.fetch_val(query)

fastapi_book_server/app/services/sequence.py

@@ -1,6 +1,6 @@
 from app.models import Sequence
 
-from app.services.common import TRGMSearchService
+from app.services.common import TRGMSearchService, GetRandomService
 
 
 GET_OBJECT_IDS_QUERY = """
@@ -33,3 +33,7 @@ class SequenceTGRMSearchService(TRGMSearchService):
     MODEL_CLASS = Sequence
     PREFETCH_RELATED = ["source"]
     GET_OBJECT_IDS_QUERY = GET_OBJECT_IDS_QUERY
+
+
+class GetRandomSequenceService(GetRandomService):
+    MODEL_CLASS = Sequence

fastapi_book_server/app/views/author.py

@@ -9,7 +9,7 @@ from app.utils.pagination import CustomPage
 from app.models import Author as AuthorDB, AuthorAnnotation as AuthorAnnotationDB, Book as BookDB
 from app.serializers.author import Author, CreateAuthor, UpdateAuthor, AuthorBook, TranslatedBook
 from app.serializers.author_annotation import AuthorAnnotation
-from app.services.author import AuthorTGRMSearchService
+from app.services.author import AuthorTGRMSearchService, GetRandomAuthorService
 from app.depends import check_token
 
 
@@ -42,9 +42,7 @@ async def create_author(data: CreateAuthor):
 
 @author_router.get("/random", response_model=Author)
 async def get_random_author():
-    author_ids: list[int] = await AuthorDB.objects.values_list("id", flatten=True)
-
-    author_id = random_choice(author_ids)
+    author_id = await GetRandomAuthorService.get_random_id()
 
     return await AuthorDB.objects.prefetch_related(PREFETCH_RELATED).get(id=author_id)
 

fastapi_book_server/app/views/book.py

@@ -10,7 +10,7 @@ from app.utils.pagination import CustomPage
 from app.models import Book as BookDB, Author as AuthorDB, BookAnnotation as BookAnnotationDB
 from app.serializers.book import Book, RemoteBook, BookDetail, CreateBook, UpdateBook, CreateRemoteBook
 from app.serializers.book_annotation import BookAnnotation
-from app.services.book import BookTGRMSearchService, BookCreator
+from app.services.book import BookTGRMSearchService, GetRandomBookService, BookCreator
 from app.filters.book import get_book_filter
 from app.depends import check_token
 
@@ -41,9 +41,7 @@ async def create_book(data: Union[CreateBook, CreateRemoteBook]):
 
 @book_router.get("/random", response_model=BookDetail)
 async def get_random_book():
-    book_ids: list[int] = await BookDB.objects.filter(is_deleted=False).values_list("id", flatten=True)
-
-    book_id = random_choice(book_ids)
+    book_id = await GetRandomBookService.get_random_id()
 
     return await BookDB.objects.select_related(SELECT_RELATED_FIELDS).get(id=book_id)
 

fastapi_book_server/app/views/sequence.py

@@ -8,7 +8,7 @@ from app.utils.pagination import CustomPage
 
 from app.models import Sequence as SequenceDB, Book as BookDB, BookSequences as BookSequencesDB
 from app.serializers.sequence import Sequence, CreateSequence, Book as SequenceBook
-from app.services.sequence import SequenceTGRMSearchService
+from app.services.sequence import SequenceTGRMSearchService, GetRandomSequenceService
 from app.depends import check_token
 
 
@@ -28,9 +28,7 @@ async def get_sequences():
 
 @sequence_router.get("/random", response_model=Sequence)
 async def get_random_sequence():
-    sequence_ids: list[int] = await SequenceDB.objects.values_list("id", flatten=True)
-
-    sequence_id = random_choice(sequence_ids)
+    sequence_id = await GetRandomSequenceService.get_random_id()
 
     return await SequenceDB.objects.get(id=sequence_id)