refactor unique constraint bad request logic

src/crud.py

@@ -9,7 +9,7 @@
 from src import models, schemas
 
 
-def _create_unique_constrain_error_msg(exc: IntegrityError) -> Optional[str]:
+def create_unique_constrain_error_msg(exc: IntegrityError) -> Optional[str]:
     pattern = r"^UNIQUE constraint failed: ([a-z_]+)\.([a-z_]+)$"
     for arg in exc.orig.args:
         assert isinstance(arg, str)
@@ -22,11 +22,6 @@ def _create_unique_constrain_error_msg(exc: IntegrityError) -> Optional[str]:
     return None
 
 
-def _handle_integrity_error(exc: IntegrityError):
-    if error_msg := _create_unique_constrain_error_msg(exc):
-        raise HTTPException(400, error_msg)
-
-
 # User
 
 
@@ -40,11 +35,7 @@ def read_user(db: Session, username: str) -> Optional[models.User]:
 def create_customer(db: Session, customer: schemas.CustomerCreate) -> models.Customer:
     db_customer = models.Customer(**customer.dict())
     db.add(db_customer)
-    try:
-        db.commit()
-    except IntegrityError as exc:
-        _handle_integrity_error(exc)
-        raise
+    db.commit()
     return db_customer
 
 
@@ -78,11 +69,7 @@ def update_customer(
     for attr, value in customer.dict(exclude={"id"}, exclude_unset=True).items():
         setattr(db_customer, attr, value)
     db.add(db_customer)
-    try:
-        db.commit()
-    except IntegrityError as exc:
-        _handle_integrity_error(exc)
-        raise
+    db.commit()
     return db_customer
 
 
@@ -92,11 +79,7 @@ def update_customer(
 def create_menu_category(db: Session, category: schemas.MenuCategoryCreate) -> models.MenuCategory:
     db_category = models.MenuCategory(**category.dict())
     db.add(db_category)
-    try:
-        db.commit()
-    except IntegrityError as exc:
-        _handle_integrity_error(exc)
-        raise
+    db.commit()
     return db_category
 
 
@@ -119,11 +102,7 @@ def update_menu_category(
     for attr, value in category.dict(exclude={"id"}, exclude_unset=True).items():
         setattr(db_category, attr, value)
     db.add(db_category)
-    try:
-        db.commit()
-    except IntegrityError as exc:
-        _handle_integrity_error(exc)
-        raise
+    db.commit()
     return db_category
 
 
@@ -133,11 +112,7 @@ def update_menu_category(
 def create_menu_item(db: Session, menu_item: schemas.MenuItemCreate) -> models.MenuItem:
     db_menu_item = models.MenuItem(**menu_item.dict())
     db.add(db_menu_item)
-    try:
-        db.commit()
-    except IntegrityError as exc:
-        _handle_integrity_error(exc)
-        raise
+    db.commit()
     return db_menu_item
 
 
@@ -161,11 +136,7 @@ def update_menu_item(
     for attr, value in menu_item.dict(exclude={"id"}, exclude_unset=True).items():
         setattr(db_menu_item, attr, value)
     db.add(db_menu_item)
-    try:
-        db.commit()
-    except IntegrityError as exc:
-        _handle_integrity_error(exc)
-        raise
+    db.commit()
     return db_menu_item
 
 
@@ -175,11 +146,7 @@ def update_menu_item(
 def create_campaign(db: Session, campaign: schemas.CampaignCreate) -> models.Campaign:
     db_campaign = models.Campaign(**campaign.dict())
     db.add(db_campaign)
-    try:
-        db.commit()
-    except IntegrityError as exc:
-        _handle_integrity_error(exc)
-        raise
+    db.commit()
     return db_campaign
 
 
@@ -200,11 +167,7 @@ def update_campaign(
     for attr, value in campaign.dict(exclude={"id"}, exclude_unset=True).items():
         setattr(db_campaign, attr, value)
     db.add(db_campaign)
-    try:
-        db.commit()
-    except IntegrityError as exc:
-        _handle_integrity_error(exc)
-        raise
+    db.commit()
     return db_campaign
 
 

src/main.py

@@ -2,12 +2,13 @@
 import sys
 import traceback
 
-from fastapi import FastAPI, Request
+from fastapi import FastAPI, HTTPException, Request
 from fastapi.middleware.cors import CORSMiddleware
 from fastapi.responses import JSONResponse
 from fastapi_pagination import add_pagination
+from sqlalchemy.exc import IntegrityError
 
-from src import routes, settings
+from src import crud, routes, settings
 
 logger = logging.getLogger("bakery")
 
@@ -22,6 +23,13 @@ def startup():
         logger.info("Settings\n%s", "\n".join(pretty_settings))
 
 
+@app.exception_handler(IntegrityError)
+def handle_integrity_error(request: Request, exc: IntegrityError):
+    """Convert DB UniqueConstraint failures to 400 BadRequest failures"""
+    if error_msg := crud.create_unique_constrain_error_msg(exc):
+        return JSONResponse({"detail": error_msg}, 400)
+
+
 async def catch_exceptions_middleware(request: Request, call_next):
     """
     Ensure CORS headers are added to response when an unhandled exception occurs: