feat: code improvements

Signed-off-by: Adetokunbo Ige <[email protected]>

Author: Adetokunbo Ige

todo-app/lambda_function/lambda.py

@@ -75,8 +75,10 @@ class UpdateTodoRequest(BaseModel):
 # PUT endpoint to update a todo item
 @app.put("/todos/{id}", response_model=TodoItem)
 async def update_todo(id: str, request: UpdateTodoRequest):
-    # Use the current timestamp if one is not provided
-    timestamp = request.timestamp or int(time.time())
+    # Ensure you are using the correct timestamp
+    timestamp = request.timestamp
+    if not timestamp:
+        raise HTTPException(status_code=400, detail="Missing 'timestamp' for identifying the item to update.")
 
     if not request.text:
         raise HTTPException(status_code=400, detail="Missing 'text' in request body")
@@ -96,12 +98,13 @@ async def update_todo(id: str, request: UpdateTodoRequest):
     update_expression = "SET " + ", ".join(update_expressions)
 
     try:
-        # Update the item in the DynamoDB table
+        # Use a ConditionExpression to ensure the item exists before updating
         response = table.update_item(
             Key={"id": id, "timestamp": timestamp},
             UpdateExpression=update_expression,
             ExpressionAttributeNames=expression_attribute_names,
             ExpressionAttributeValues=expression_attribute_values,
+            ConditionExpression="attribute_exists(id) AND attribute_exists(timestamp)",
             ReturnValues="ALL_NEW"
         )
 
@@ -113,6 +116,8 @@ async def update_todo(id: str, request: UpdateTodoRequest):
         return updated_todo
 
     except ClientError as e:
+        if e.response['Error']['Code'] == 'ConditionalCheckFailedException':
+            raise HTTPException(status_code=404, detail="Todo not found")
         logging.error(f"ClientError updating todo: {e}")
         raise HTTPException(status_code=500, detail="Error updating todo")
     except Exception as e:
@@ -121,23 +126,20 @@ async def update_todo(id: str, request: UpdateTodoRequest):
 
 # Delete a todo item in the DynamoDB table
 @app.delete("/todos/{id}", status_code=204)
-async def delete_todo(id: str, timestamp: Optional[int] = None):
-    # Use the current timestamp if one is not provided
-    timestamp = timestamp or int(time.time())
-
+async def delete_todo(id: str, timestamp: int):
     try:
         # Attempt to delete the item using both the partition key (id) and sort key (timestamp)
         response = table.delete_item(Key={"id": id, "timestamp": timestamp})
 
-        # Check if the HTTP status code indicates a successful deletion
-        status_code = response.get("ResponseMetadata", {}).get("HTTPStatusCode")
-        if status_code != 200:
-            logging.warning(f"Delete operation failed for id {id} and timestamp {timestamp}: {response}")
+        # Check if the deletion was successful by checking the response metadata
+        if response.get("ResponseMetadata", {}).get("HTTPStatusCode") != 200:
+            logging.warning(f"Delete operation failed for id {id}: {response}")
             raise HTTPException(status_code=404, detail="Todo not found")
 
         logging.debug(f"Deleted item with id: {id} and timestamp: {timestamp}")
-        # Return nothing (status code 204)
-        return
+        
+        # No content needs to be returned for status code 204, just confirm the deletion was successful
+        return {"detail": "Todo deleted successfully"}
 
     except ClientError as e:
         logging.error(f"ClientError deleting todo with id {id}: {e}")