refactor(frontend): replace useAsyncTask with TanStack Query

Author: ivanskv2000

CONTRIBUTING.md

@@ -23,6 +23,7 @@ You can open an [issue](https://github.com/ivanskv2000/evsy/issues) — we’d l
 You can setup both the backend and frontend in dev mode with hot-reloading:
 
 ```bash
+cp .env.example .env
 make dev
 ```
 

backend/app/api/v1/routes/events.py

@@ -42,7 +42,13 @@ def create_event_route(event: EventCreate, db: Session = Depends(get_db)):
     db_fields = get_fields_by_ids(db, event.fields)
 
     if len(db_fields) != len(event.fields):
-        raise HTTPException(status_code=400, detail="One or more fields do not exist.")
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail={
+                "code": "invalid_reference",
+                "message": "One or more referenced fields do not exist.",
+            },
+        )
 
     get_or_create_tags(db, event.tags)
     db_event = event_crud.create_event(db=db, event=event)
@@ -63,7 +69,13 @@ def create_event_route(event: EventCreate, db: Session = Depends(get_db)):
 def get_event_route(event_id: int, db: Session = Depends(get_db)):
     db_event = event_crud.get_event(db=db, event_id=event_id)
     if db_event is None:
-        raise HTTPException(status_code=404, detail="Event not found")
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "code": "resource_not_found",
+                "message": f"Event with id {event_id} not found",
+            },
+        )
     return db_event
 
 
@@ -100,12 +112,24 @@ def update_event_route(
     db_fields = get_fields_by_ids(db, event.fields)
 
     if len(db_fields) != len(event.fields):
-        raise HTTPException(status_code=400, detail="One or more fields do not exist.")
+        raise HTTPException(
+            status_code=status.HTTP_400_BAD_REQUEST,
+            detail={
+                "code": "invalid_reference",
+                "message": "One or more referenced fields do not exist.",
+            },
+        )
 
     get_or_create_tags(db, event.tags)
     db_event = event_crud.update_event(db=db, event_id=event_id, event=event)
     if db_event is None:
-        raise HTTPException(status_code=404, detail="Event not found")
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "code": "resource_not_found",
+                "message": f"Event with id {event_id} not found",
+            },
+        )
     return db_event
 
 
@@ -122,7 +146,13 @@ def update_event_route(
 def delete_event_route(event_id: int, db: Session = Depends(get_db)):
     db_event = event_crud.delete_event(db=db, event_id=event_id)
     if db_event is None:
-        raise HTTPException(status_code=404, detail="Event not found")
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "code": "resource_not_found",
+                "message": f"Event with id {event_id} not found",
+            },
+        )
     return db_event
 
 
@@ -151,7 +181,13 @@ def get_event_json_schema(
 ):
     db_event = event_crud.get_event(db=db, event_id=event_id)
     if not db_event:
-        raise HTTPException(status_code=404, detail="Event not found")
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "code": "resource_not_found",
+                "message": f"Event with id {event_id} not found",
+            },
+        )
 
     event = EventOut.model_validate(db_event)
     schema = generate_json_schema_for_event(
@@ -187,7 +223,13 @@ def get_event_yaml_schema(
 ):
     db_event = event_crud.get_event(db=db, event_id=event_id)
     if not db_event:
-        raise HTTPException(status_code=404, detail="Event not found")
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "code": "resource_not_found",
+                "message": f"Event with id {event_id} not found",
+            },
+        )
 
     event = EventOut.model_validate(db_event)
     schema = generate_json_schema_for_event(

backend/app/api/v1/routes/fields.py

@@ -56,7 +56,13 @@ def get_field_route(
 ):
     db_field = field_crud.get_field(db=db, field_id=field_id)
     if db_field is None:
-        raise HTTPException(status_code=404, detail="Field not found")
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "code": "resource_not_found",
+                "message": f"Field with id {field_id} not found",
+            },
+        )
 
     if with_event_count:
         count = field_crud.get_field_event_count(db=db, field_id=field_id)
@@ -81,7 +87,13 @@ def update_field_route(
 ):
     db_field = field_crud.update_field(db=db, field_id=field_id, field=field)
     if db_field is None:
-        raise HTTPException(status_code=404, detail="Field not found")
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "code": "resource_not_found",
+                "message": f"Field with id {field_id} not found",
+            },
+        )
     return db_field
 
 
@@ -98,5 +110,11 @@ def update_field_route(
 def delete_field_route(field_id: int, db: Session = Depends(get_db)):
     db_field = field_crud.delete_field(db=db, field_id=field_id)
     if db_field is None:
-        raise HTTPException(status_code=404, detail="Field not found")
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "code": "resource_not_found",
+                "message": f"Field with id {field_id} not found",
+            },
+        )
     return db_field

backend/app/api/v1/routes/tags.py

@@ -50,7 +50,13 @@ def list_tags_route(db: Session = Depends(get_db)):
 def get_tag_route(tag_id: str, db: Session = Depends(get_db)):
     db_tag = tag_crud.get_tag(db=db, tag_id=tag_id)
     if db_tag is None:
-        raise HTTPException(status_code=404, detail="Tag not found")
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "code": "resource_not_found",
+                "message": f"Tag with id {tag_id!r} not found",
+            },
+        )
     return db_tag
 
 
@@ -68,7 +74,13 @@ def get_tag_route(tag_id: str, db: Session = Depends(get_db)):
 def update_tag_route(tag_id: str, tag: TagCreate, db: Session = Depends(get_db)):
     db_tag = tag_crud.update_tag(db=db, tag_id=tag_id, tag=tag)
     if db_tag is None:
-        raise HTTPException(status_code=404, detail="Tag not found")
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "code": "resource_not_found",
+                "message": f"Tag with id {tag_id!r} not found",
+            },
+        )
     return db_tag
 
 
@@ -85,5 +97,11 @@ def update_tag_route(tag_id: str, tag: TagCreate, db: Session = Depends(get_db))
 def delete_tag_route(tag_id: str, db: Session = Depends(get_db)):
     db_tag = tag_crud.delete_tag(db=db, tag_id=tag_id)
     if db_tag is None:
-        raise HTTPException(status_code=404, detail="Tag not found")
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND,
+            detail={
+                "code": "resource_not_found",
+                "message": f"Tag with id {tag_id!r} not found",
+            },
+        )
     return db_tag

backend/app/core/guard.py

@@ -1,17 +1,25 @@
-from fastapi import Depends, HTTPException
+from fastapi import Depends, HTTPException, status
 
 from app.settings import get_settings
 
 
 def ensure_not_demo(settings=Depends(get_settings)):
     if settings.is_demo:
         raise HTTPException(
-            status_code=403, detail="This action is not allowed in demo mode."
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail={
+                "code": "action_forbidden_in_demo",
+                "message": "This action is not allowed in demo mode.",
+            },
         )
 
 
 def ensure_dev(settings=Depends(get_settings)):
     if not settings.is_dev:
         raise HTTPException(
-            status_code=403, detail="This action is allowed only in development."
+            status_code=status.HTTP_403_FORBIDDEN,
+            detail={
+                "code": "action_requires_dev_mode",
+                "message": "This action is allowed only in development.",
+            },
         )

backend/app/core/handlers.py

@@ -0,0 +1,62 @@
+from fastapi import Request, status
+from fastapi.encoders import jsonable_encoder
+from fastapi.exceptions import RequestValidationError
+from fastapi.responses import JSONResponse
+from pydantic import BaseModel, Field
+from starlette.exceptions import HTTPException as StarletteHTTPException
+
+
+class ValidationErrorDetail(BaseModel):
+    loc: tuple[str | int, ...] = Field(
+        ..., description="Location of the error in the request"
+    )
+    msg: str = Field(..., description="A human-readable message for the error")
+    type: str = Field(..., description="The type of the error")
+
+
+class ErrorResponse(BaseModel):
+    code: str = Field(..., description="A unique, machine-readable error code")
+    message: str = Field(..., description="A human-readable message for the error")
+    details: list[ValidationErrorDetail] | None = Field(
+        None, description="Optional details for validation errors"
+    )
+
+
+async def http_exception_handler(request: Request, exc: StarletteHTTPException):
+    """
+    Handler for FastAPI's built-in HTTPException.
+
+    This handler formats the error into a standard ErrorResponse model.
+    It supports passing a dictionary with 'code' and 'message' in exc.detail.
+    """
+    if isinstance(exc.detail, dict):
+        # If detail is a dict, assume it matches our convention
+        code = exc.detail.get("code", "http_exception")
+        message = exc.detail.get("message", "An unexpected error occurred.")
+    else:
+        # If detail is a string, wrap it in the standard format
+        code = "http_exception"
+        message = str(exc.detail)
+
+    return JSONResponse(
+        status_code=exc.status_code,
+        content=jsonable_encoder(ErrorResponse(code=code, message=message)),
+    )
+
+
+async def validation_exception_handler(request: Request, exc: RequestValidationError):
+    """Handler for Pydantic's RequestValidationError."""
+    details = [
+        ValidationErrorDetail(loc=err["loc"], msg=err["msg"], type=err["type"])
+        for err in exc.errors()
+    ]
+    return JSONResponse(
+        status_code=status.HTTP_422_UNPROCESSABLE_ENTITY,
+        content=jsonable_encoder(
+            ErrorResponse(
+                code="validation_error",
+                message="Input validation failed",
+                details=details,
+            )
+        ),
+    )

backend/app/factory.py

@@ -1,10 +1,13 @@
 from contextlib import asynccontextmanager
 
 from fastapi import FastAPI
+from fastapi.exceptions import RequestValidationError
 from fastapi.middleware.cors import CORSMiddleware
 from sqlalchemy.orm import sessionmaker
+from starlette.exceptions import HTTPException as StarletteHTTPException
 
 from app.api.v1.routes import admin, auth, events, fields, generic, tags
+from app.core.handlers import http_exception_handler, validation_exception_handler
 from app.modules.auth.schemas import UserCreate
 from app.modules.auth.service import create_user_if_not_exists
 from app.settings import Settings
@@ -77,6 +80,9 @@ async def lifespan(app: FastAPI):
     app.include_router(admin.router, prefix="/v1", tags=["admin"])
     app.include_router(auth.router, prefix="/v1", tags=["auth"])
 
+    app.add_exception_handler(StarletteHTTPException, http_exception_handler)
+    app.add_exception_handler(RequestValidationError, validation_exception_handler)
+
     @app.get("/")
     def read_root():
         return {"message": "Welcome to the Evsy API!"}

backend/tests/test_auth.py

@@ -21,7 +21,7 @@ def test_signup_duplicate_email(client, auth_data):
     # Repeat signup to trigger duplicate error
     response = client.post("/v1/auth/signup", json=auth_data)
     assert response.status_code == 400
-    assert "already exists" in response.json()["detail"].lower()
+    assert "already exists" in response.json()["message"].lower()
 
 
 def test_login_with_valid_credentials(client, auth_data):
@@ -38,7 +38,7 @@ def test_login_with_invalid_password(client, auth_data):
         json={"email": auth_data["email"], "password": "wrongpassword"},
     )
     assert response.status_code == 401
-    assert "invalid credentials" in response.json()["detail"].lower()
+    assert "invalid credentials" in response.json()["message"].lower()
 
 
 def test_login_with_unknown_email(client):
@@ -47,7 +47,7 @@ def test_login_with_unknown_email(client):
         json={"email": "unknown@example.com", "password": "irrelevant"},
     )
     assert response.status_code == 401
-    assert "invalid credentials" in response.json()["detail"].lower()
+    assert "invalid credentials" in response.json()["message"].lower()
 
 
 def test_me_requires_auth(client):

backend/tests/test_events.py

@@ -37,7 +37,7 @@ def test_create_event_with_invalid_field(auth_client):
         },
     )
     assert response.status_code == 400
-    assert "fields" in response.json()["detail"].lower()
+    assert "fields" in response.json()["message"].lower()
 
 
 def test_create_event_with_new_tag(auth_client):

backend/tests/test_events_extended.py

@@ -119,7 +119,7 @@ def test_get_nonexistent_event(auth_client):
     """Test getting event that doesn't exist"""
     response = auth_client.get("/v1/events/99999")
     assert response.status_code == 404
-    assert "not found" in response.json()["detail"].lower()
+    assert "not found" in response.json()["message"].lower()
 
 
 def test_update_nonexistent_event(auth_client):