feat(printers): add slug lookup + unified slug/uuid resolver

resolve_by_slug_or_uuid akzeptiert beides für menschen-lesbare API-Pfade.

Refs strausmann/hangar#78

Author: strausmann

backend/app/repositories/printers.py

@@ -34,3 +34,23 @@ async def create(session: AsyncSession, printer: Printer) -> Printer:
     await session.commit()
     await session.refresh(printer)
     return printer
+
+
+async def get_by_slug(session: AsyncSession, slug: str) -> Printer | None:
+    """Lookup nach slug. None wenn nicht vorhanden."""
+    result = await session.execute(
+        select(Printer).where(col(Printer.slug) == slug)
+    )
+    return result.scalar_one_or_none()
+
+
+async def resolve_by_slug_or_uuid(session: AsyncSession, key: str) -> Printer | None:
+    """Akzeptiert Slug-String ODER UUID-String. UUID hat Vorrang (Performance)."""
+    try:
+        uuid_obj = UUID(key)
+        printer = await get(session, uuid_obj)
+        if printer is not None:
+            return printer
+    except ValueError:
+        pass
+    return await get_by_slug(session, key)

backend/tests/integration/db/test_printer_slug_resolution.py

@@ -0,0 +1,53 @@
+"""Repository-Tests für slug-Lookup und Slug-oder-UUID-Resolution."""
+from __future__ import annotations
+
+from uuid import uuid4
+
+import pytest
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.models.printer import Printer
+from app.repositories import printers as printers_repo
+
+
+@pytest.mark.asyncio
+async def test_get_by_slug_returns_printer(db_session: AsyncSession):
+    p = Printer(name="Brother PT-P750W", slug="brother-p750w",
+                model="PT-P750W", backend="ptouch")
+    await printers_repo.create(db_session, p)
+
+    found = await printers_repo.get_by_slug(db_session, "brother-p750w")
+    assert found is not None
+    assert found.id == p.id
+
+
+@pytest.mark.asyncio
+async def test_get_by_slug_returns_none_when_missing(db_session: AsyncSession):
+    found = await printers_repo.get_by_slug(db_session, "does-not-exist")
+    assert found is None
+
+
+@pytest.mark.asyncio
+async def test_resolve_by_slug_or_uuid_with_uuid(db_session: AsyncSession):
+    p = Printer(name="X", slug="x", model="X", backend="mock")
+    await printers_repo.create(db_session, p)
+
+    found = await printers_repo.resolve_by_slug_or_uuid(db_session, str(p.id))
+    assert found is not None
+    assert found.id == p.id
+
+
+@pytest.mark.asyncio
+async def test_resolve_by_slug_or_uuid_with_slug(db_session: AsyncSession):
+    p = Printer(name="Y", slug="my-printer", model="Y", backend="mock")
+    await printers_repo.create(db_session, p)
+
+    found = await printers_repo.resolve_by_slug_or_uuid(db_session, "my-printer")
+    assert found is not None
+    assert found.id == p.id
+
+
+@pytest.mark.asyncio
+async def test_resolve_by_slug_or_uuid_with_garbage(db_session: AsyncSession):
+    found = await printers_repo.resolve_by_slug_or_uuid(db_session, "nonexistent")
+    assert found is None