⚡ Bolt: optimize stream model validation with from_attributes

.jules/bolt.md

@@ -9,3 +9,7 @@
 ## 2025-05-15 - [GraphQL] Rejected: TypeAdapter for List Validation
 **Learning:** While `pydantic.TypeAdapter(list[Model])` provides a theoretical ~65% performance improvement over list comprehensions by leveraging Rust-based batch processing, it may be rejected if the perceived value is low relative to the original implementation's simplicity, especially in template code.
 **Action:** Prioritize optimizations that have a dramatic and undeniable impact on core latency or resource consumption.
+
+## 2026-06-10 - [Stream] Faster Cross-Model Validation with from_attributes
+**Learning:** When validating a Pydantic model using data from another Pydantic model (e.g., transforming a `SourceItem` to a `DestinationItem`), using `Model.model_validate(other_model, from_attributes=True)` is significantly faster and more memory-efficient than `Model.model_validate(other_model.model_dump())`. It bypasses the overhead of serializing the source model into an intermediate Python dictionary.
+**Action:** Use `from_attributes=True` for efficient model-to-model transformations, especially in high-throughput data processing paths like DynamoDB Streams or SQS batch processing.

templates/stream/handler.py

@@ -3,7 +3,6 @@
 from aws_lambda_powertools.utilities.batch import BatchProcessor, EventType, process_partial_response
 from aws_lambda_powertools.utilities.data_classes.dynamo_db_stream_event import DynamoDBRecord
 from aws_lambda_powertools.utilities.typing import LambdaContext
-from boto3.dynamodb.types import TypeDeserializer
 from pydantic import ValidationError
 
 from templates.repository import Repository
@@ -42,7 +41,8 @@ def _process(self, item: SourceItem) -> DestinationItem | None:
         """
         try:
             # TODO: process here
-            return DestinationItem.model_validate(item.model_dump(by_alias=True))
+            # Use from_attributes=True to validate directly from SourceItem without redundant model_dump()
+            return DestinationItem.model_validate(item, from_attributes=True)
         except ValidationError as exc:
             logger.error("DestinationItem validation failed", exc_info=exc)
             return None

templates/stream/models.py

@@ -2,11 +2,11 @@
 from pydantic.alias_generators import to_camel
 
 
-class SourceItem(BaseModel, populate_by_name=True, alias_generator=to_camel):
+class SourceItem(BaseModel, populate_by_name=True, alias_generator=to_camel, from_attributes=True):
     id: str = Field(description="Unique item identifier", min_length=1, max_length=50)
     name: str | None = Field(default=None, description="Human-readable item name", min_length=1, max_length=100)
 
 
-class DestinationItem(BaseModel, populate_by_name=True, alias_generator=to_camel):
+class DestinationItem(BaseModel, populate_by_name=True, alias_generator=to_camel, from_attributes=True):
     id: str = Field(description="Unique item identifier", min_length=1, max_length=50)
     name: str | None = Field(default=None, description="Human-readable item name", min_length=1, max_length=100)