Add graphql characters filter

app/graphql/schemas.py

@@ -13,6 +13,11 @@
     Season as SeasonModel,
     SeasonDoesNotExist,
 )
+from app.repositories.models import (
+    CharacterGenderFilter,
+    CharacterSpeciesFilter,
+    CharacterStatusFilter,
+)
 from app.repositories.sessions import get_async_session_ctx
 from app.services.base import EpisodeBase as EpisodeBaseSchema
 from app.services.characters import Character as CharacterSchema
@@ -26,6 +31,22 @@
 )
 
 
+class BaseQueryException(Exception):
+    ...
+
+
+class CharacterQueryException(BaseQueryException):
+    ...
+
+
+class LimitViolation(CharacterQueryException):
+    ...
+
+
+class OffsetViolation(CharacterQueryException):
+    ...
+
+
 @strawberry.experimental.pydantic.type(model=CharacterSchema)
 class Character:
     id: strawberry.auto
@@ -37,6 +58,26 @@ class Character:
     image: strawberry.auto
 
 
+@strawberry.type
+class Characters:
+    limit: int
+    offset: int
+    total: int
+    edges: List[Character]
+
+    @classmethod
+    def from_params(cls, characters, limit: int, offset: int, total: int, /):
+        return cls(
+            limit=limit,
+            offset=offset,
+            total=total,
+            edges=[
+                Character.from_pydantic(CharacterSchema.model_validate(character))
+                for character in characters
+            ],
+        )
+
+
 @strawberry.experimental.pydantic.type(model=SeasonEpisodeSchema, all_fields=True)
 class SeasonEpisode:
     ...
@@ -84,6 +125,42 @@ async def character(self, character_id: int) -> Character | None:
                 return None
         return Character.from_pydantic(CharacterSchema.model_validate(character))
 
+    @strawberry.field()
+    async def characters(
+        self,
+        *,
+        limit: int | None = 50,
+        offset: int | None = 0,
+        gender: strawberry.enum(CharacterGenderFilter) | None = None,
+        status: strawberry.enum(CharacterStatusFilter) | None = None,
+        species: strawberry.enum(CharacterSpeciesFilter) | None = None,
+    ) -> Characters:
+        # For some reason self does not work under strawberry decorator,
+        # so class attrs can't be used. Please find another way.
+        _min_l: int = 1
+        _max_l: int = 50
+        _min_offset: int = 0
+        if not _min_l <= limit <= _max_l:
+            raise LimitViolation(
+                f"Limit can be more than {_min_l} and less than {_max_l}"
+            ) from None
+
+        async with get_async_session_ctx() as session:
+            total: int = await CharacterModel.count(session)
+            if not _min_offset <= offset <= total:
+                raise LimitViolation(
+                    f"Offset can't be less than {_min_offset} more than {total}"
+                ) from None
+            characters = await CharacterModel.filter(
+                session,
+                limit=limit,
+                offset=offset,
+                gender=gender,
+                character_status=status,
+                species=species,
+            )
+        return Characters.from_params(characters, limit, offset, total)
+
     @strawberry.field()
     async def episode(self, episode_id: int) -> Episode | None:
         async with get_async_session_ctx() as session: