From 64798c42b9b5da3c6cbbb4283aa24cb352e963e4 Mon Sep 17 00:00:00 2001
From: Ruben Fonseca <rubefons@amazon.com>
Date: Wed, 22 Nov 2023 15:05:43 +0100
Subject: [PATCH 1/6] chore(event_handler): only apply serialization at the end

---
 aws_lambda_powertools/event_handler/api_gateway.py |  2 ++
 tests/functional/event_handler/test_api_gateway.py | 12 ++++++------
 tests/functional/event_handler/test_base_path.py   | 12 ++++++------
 3 files changed, 14 insertions(+), 12 deletions(-)

diff --git a/aws_lambda_powertools/event_handler/api_gateway.py b/aws_lambda_powertools/event_handler/api_gateway.py
index 05831a2eea5..01498c41526 100644
--- a/aws_lambda_powertools/event_handler/api_gateway.py
+++ b/aws_lambda_powertools/event_handler/api_gateway.py
@@ -790,6 +790,8 @@ def build(self, event: ResponseEventT, cors: Optional[CORSConfig] = None) -> Dic
             logger.debug("Encoding bytes response with base64")
             self.response.base64_encoded = True
             self.response.body = base64.b64encode(self.response.body).decode()
+        elif self.response.is_json():
+            self.response.body = self.serializer(self.response.body)
 
         # We only apply the serializer when the content type is JSON and the
         # body is not a str, to avoid double encoding
diff --git a/tests/functional/event_handler/test_api_gateway.py b/tests/functional/event_handler/test_api_gateway.py
index d4c88b541aa..4fe56cf8756 100644
--- a/tests/functional/event_handler/test_api_gateway.py
+++ b/tests/functional/event_handler/test_api_gateway.py
@@ -368,7 +368,7 @@ def test_override_route_compress_parameter():
     # AND the Response object with compress=False
     app = ApiGatewayResolver()
     mock_event = {"path": "/my/request", "httpMethod": "GET", "headers": {"Accept-Encoding": "deflate, gzip"}}
-    expected_value = '{"test": "value"}'
+    expected_value = {"test": "value"}
 
     @app.get("/my/request", compress=True)
     def with_compression() -> Response:
@@ -382,7 +382,7 @@ def handler(event, context):
 
     # THEN the response is not compressed
     assert result["isBase64Encoded"] is False
-    assert result["body"] == expected_value
+    assert json.loads(result["body"]) == expected_value
     assert result["multiValueHeaders"].get("Content-Encoding") is None
 
 
@@ -682,7 +682,7 @@ def another_one():
 def test_no_content_response():
     # GIVEN a response with no content-type or body
     response = Response(status_code=204, content_type=None, body=None, headers=None)
-    response_builder = ResponseBuilder(response)
+    response_builder = ResponseBuilder(response, serializer=json.dumps)
 
     # WHEN calling to_dict
     result = response_builder.build(APIGatewayProxyEvent(LOAD_GW_EVENT))
@@ -1528,7 +1528,7 @@ def get_lambda() -> Response:
     # THEN call the exception_handler
     assert result["statusCode"] == 500
     assert result["multiValueHeaders"]["Content-Type"] == [content_types.APPLICATION_JSON]
-    assert result["body"] == "CUSTOM ERROR FORMAT"
+    assert result["body"] == '"CUSTOM ERROR FORMAT"'
 
 
 def test_exception_handler_not_found():
@@ -1824,11 +1824,11 @@ def test_route_match_prioritize_full_match():
 
     @router.get("/my/{path}")
     def dynamic_handler() -> Response:
-        return Response(200, content_types.APPLICATION_JSON, json.dumps({"hello": "dynamic"}))
+        return Response(200, content_types.APPLICATION_JSON, {"hello": "dynamic"})
 
     @router.get("/my/path")
     def static_handler() -> Response:
-        return Response(200, content_types.APPLICATION_JSON, json.dumps({"hello": "static"}))
+        return Response(200, content_types.APPLICATION_JSON, {"hello": "static"})
 
     app.include_router(router)
 
diff --git a/tests/functional/event_handler/test_base_path.py b/tests/functional/event_handler/test_base_path.py
index 479a46bda55..adf3c5849df 100644
--- a/tests/functional/event_handler/test_base_path.py
+++ b/tests/functional/event_handler/test_base_path.py
@@ -21,7 +21,7 @@ def handle():
 
     result = app(event, {})
     assert result["statusCode"] == 200
-    assert result["body"] == ""
+    assert result["body"] == '""'
 
 
 def test_base_path_api_gateway_http():
@@ -38,7 +38,7 @@ def handle():
 
     result = app(event, {})
     assert result["statusCode"] == 200
-    assert result["body"] == ""
+    assert result["body"] == '""'
 
 
 def test_base_path_alb():
@@ -53,7 +53,7 @@ def handle():
 
     result = app(event, {})
     assert result["statusCode"] == 200
-    assert result["body"] == ""
+    assert result["body"] == '""'
 
 
 def test_base_path_lambda_function_url():
@@ -70,7 +70,7 @@ def handle():
 
     result = app(event, {})
     assert result["statusCode"] == 200
-    assert result["body"] == ""
+    assert result["body"] == '""'
 
 
 def test_vpc_lattice():
@@ -85,7 +85,7 @@ def handle():
 
     result = app(event, {})
     assert result["statusCode"] == 200
-    assert result["body"] == ""
+    assert result["body"] == '""'
 
 
 def test_vpc_latticev2():
@@ -100,4 +100,4 @@ def handle():
 
     result = app(event, {})
     assert result["statusCode"] == 200
-    assert result["body"] == ""
+    assert result["body"] == '""'

From 8344760eb7ae15bbff128a00562c0217cb99f66b Mon Sep 17 00:00:00 2001
From: Ruben Fonseca <rubefons@amazon.com>
Date: Wed, 22 Nov 2023 14:01:51 +0100
Subject: [PATCH 2/6] fix: avoid double encoding

---
 aws_lambda_powertools/event_handler/api_gateway.py |  5 ++++-
 tests/functional/event_handler/test_api_gateway.py |  2 +-
 tests/functional/event_handler/test_base_path.py   | 12 ++++++------
 3 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/aws_lambda_powertools/event_handler/api_gateway.py b/aws_lambda_powertools/event_handler/api_gateway.py
index 01498c41526..5ec024b3c61 100644
--- a/aws_lambda_powertools/event_handler/api_gateway.py
+++ b/aws_lambda_powertools/event_handler/api_gateway.py
@@ -790,7 +790,10 @@ def build(self, event: ResponseEventT, cors: Optional[CORSConfig] = None) -> Dic
             logger.debug("Encoding bytes response with base64")
             self.response.base64_encoded = True
             self.response.body = base64.b64encode(self.response.body).decode()
-        elif self.response.is_json():
+
+        # We only apply the serializer when the content type is JSON and the
+        # body is not a str, to avoid double encoding
+        elif self.response.is_json() and not isinstance(self.response.body, str):
             self.response.body = self.serializer(self.response.body)
 
         # We only apply the serializer when the content type is JSON and the
diff --git a/tests/functional/event_handler/test_api_gateway.py b/tests/functional/event_handler/test_api_gateway.py
index 4fe56cf8756..3cd5e9a65ff 100644
--- a/tests/functional/event_handler/test_api_gateway.py
+++ b/tests/functional/event_handler/test_api_gateway.py
@@ -1528,7 +1528,7 @@ def get_lambda() -> Response:
     # THEN call the exception_handler
     assert result["statusCode"] == 500
     assert result["multiValueHeaders"]["Content-Type"] == [content_types.APPLICATION_JSON]
-    assert result["body"] == '"CUSTOM ERROR FORMAT"'
+    assert result["body"] == "CUSTOM ERROR FORMAT"
 
 
 def test_exception_handler_not_found():
diff --git a/tests/functional/event_handler/test_base_path.py b/tests/functional/event_handler/test_base_path.py
index adf3c5849df..479a46bda55 100644
--- a/tests/functional/event_handler/test_base_path.py
+++ b/tests/functional/event_handler/test_base_path.py
@@ -21,7 +21,7 @@ def handle():
 
     result = app(event, {})
     assert result["statusCode"] == 200
-    assert result["body"] == '""'
+    assert result["body"] == ""
 
 
 def test_base_path_api_gateway_http():
@@ -38,7 +38,7 @@ def handle():
 
     result = app(event, {})
     assert result["statusCode"] == 200
-    assert result["body"] == '""'
+    assert result["body"] == ""
 
 
 def test_base_path_alb():
@@ -53,7 +53,7 @@ def handle():
 
     result = app(event, {})
     assert result["statusCode"] == 200
-    assert result["body"] == '""'
+    assert result["body"] == ""
 
 
 def test_base_path_lambda_function_url():
@@ -70,7 +70,7 @@ def handle():
 
     result = app(event, {})
     assert result["statusCode"] == 200
-    assert result["body"] == '""'
+    assert result["body"] == ""
 
 
 def test_vpc_lattice():
@@ -85,7 +85,7 @@ def handle():
 
     result = app(event, {})
     assert result["statusCode"] == 200
-    assert result["body"] == '""'
+    assert result["body"] == ""
 
 
 def test_vpc_latticev2():
@@ -100,4 +100,4 @@ def handle():
 
     result = app(event, {})
     assert result["statusCode"] == 200
-    assert result["body"] == '""'
+    assert result["body"] == ""

From d9319e1db782bf30d891929a76b0d5b6567f7bb2 Mon Sep 17 00:00:00 2001
From: Ruben Fonseca <rubefons@amazon.com>
Date: Wed, 22 Nov 2023 14:06:12 +0100
Subject: [PATCH 3/6] fix: rolled back test changes

---
 tests/functional/event_handler/test_api_gateway.py | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tests/functional/event_handler/test_api_gateway.py b/tests/functional/event_handler/test_api_gateway.py
index 3cd5e9a65ff..8e9bded9c7b 100644
--- a/tests/functional/event_handler/test_api_gateway.py
+++ b/tests/functional/event_handler/test_api_gateway.py
@@ -368,7 +368,7 @@ def test_override_route_compress_parameter():
     # AND the Response object with compress=False
     app = ApiGatewayResolver()
     mock_event = {"path": "/my/request", "httpMethod": "GET", "headers": {"Accept-Encoding": "deflate, gzip"}}
-    expected_value = {"test": "value"}
+    expected_value = '{"test": "value"}'
 
     @app.get("/my/request", compress=True)
     def with_compression() -> Response:
@@ -382,7 +382,7 @@ def handler(event, context):
 
     # THEN the response is not compressed
     assert result["isBase64Encoded"] is False
-    assert json.loads(result["body"]) == expected_value
+    assert result["body"] == expected_value
     assert result["multiValueHeaders"].get("Content-Encoding") is None
 
 
@@ -1824,11 +1824,11 @@ def test_route_match_prioritize_full_match():
 
     @router.get("/my/{path}")
     def dynamic_handler() -> Response:
-        return Response(200, content_types.APPLICATION_JSON, {"hello": "dynamic"})
+        return Response(200, content_types.APPLICATION_JSON, json.dumps({"hello": "dynamic"}))
 
     @router.get("/my/path")
     def static_handler() -> Response:
-        return Response(200, content_types.APPLICATION_JSON, {"hello": "static"})
+        return Response(200, content_types.APPLICATION_JSON, json.dumps({"hello": "static"}))
 
     app.include_router(router)
 

From 8bdb410078c6a3007190782cf8cf614a2b5bb6b6 Mon Sep 17 00:00:00 2001
From: Ruben Fonseca <rubefons@amazon.com>
Date: Wed, 22 Nov 2023 15:11:28 +0100
Subject: [PATCH 4/6] fix: remove code from bad rebase

---
 aws_lambda_powertools/event_handler/api_gateway.py | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/aws_lambda_powertools/event_handler/api_gateway.py b/aws_lambda_powertools/event_handler/api_gateway.py
index 5ec024b3c61..05831a2eea5 100644
--- a/aws_lambda_powertools/event_handler/api_gateway.py
+++ b/aws_lambda_powertools/event_handler/api_gateway.py
@@ -796,11 +796,6 @@ def build(self, event: ResponseEventT, cors: Optional[CORSConfig] = None) -> Dic
         elif self.response.is_json() and not isinstance(self.response.body, str):
             self.response.body = self.serializer(self.response.body)
 
-        # We only apply the serializer when the content type is JSON and the
-        # body is not a str, to avoid double encoding
-        elif self.response.is_json() and not isinstance(self.response.body, str):
-            self.response.body = self.serializer(self.response.body)
-
         return {
             "statusCode": self.response.status_code,
             "body": self.response.body,

From add748ac9c78a293c11c80c177e174f54c31277f Mon Sep 17 00:00:00 2001
From: Ruben Fonseca <rubefons@amazon.com>
Date: Wed, 22 Nov 2023 15:13:22 +0100
Subject: [PATCH 5/6] fix: remove unused code

---
 tests/functional/event_handler/test_api_gateway.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tests/functional/event_handler/test_api_gateway.py b/tests/functional/event_handler/test_api_gateway.py
index 8e9bded9c7b..d4c88b541aa 100644
--- a/tests/functional/event_handler/test_api_gateway.py
+++ b/tests/functional/event_handler/test_api_gateway.py
@@ -682,7 +682,7 @@ def another_one():
 def test_no_content_response():
     # GIVEN a response with no content-type or body
     response = Response(status_code=204, content_type=None, body=None, headers=None)
-    response_builder = ResponseBuilder(response, serializer=json.dumps)
+    response_builder = ResponseBuilder(response)
 
     # WHEN calling to_dict
     result = response_builder.build(APIGatewayProxyEvent(LOAD_GW_EVENT))

From 84dccebb25ca68695305fa91d89593c2ea2f33c6 Mon Sep 17 00:00:00 2001
From: Ruben Fonseca <rubefons@amazon.com>
Date: Wed, 22 Nov 2023 17:29:34 +0100
Subject: [PATCH 6/6] fix(event_handler): lazy load Pydantic to improve cold
 start

---
 aws_lambda_powertools/event_handler/openapi/compat.py      | 2 +-
 aws_lambda_powertools/event_handler/openapi/models.py      | 2 +-
 aws_lambda_powertools/event_handler/openapi/params.py      | 3 ++-
 .../event_handler/openapi/pydantic_loader.py               | 6 ++++++
 aws_lambda_powertools/event_handler/openapi/types.py       | 7 -------
 tests/functional/event_handler/test_bedrock_agent.py       | 2 +-
 6 files changed, 11 insertions(+), 11 deletions(-)
 create mode 100644 aws_lambda_powertools/event_handler/openapi/pydantic_loader.py

diff --git a/aws_lambda_powertools/event_handler/openapi/compat.py b/aws_lambda_powertools/event_handler/openapi/compat.py
index 54b78f7e5f6..bd102aa7b93 100644
--- a/aws_lambda_powertools/event_handler/openapi/compat.py
+++ b/aws_lambda_powertools/event_handler/openapi/compat.py
@@ -15,9 +15,9 @@
 from pydantic import BaseModel, create_model
 from pydantic.fields import FieldInfo
 
+from aws_lambda_powertools.event_handler.openapi.pydantic_loader import PYDANTIC_V2
 from aws_lambda_powertools.event_handler.openapi.types import (
     COMPONENT_REF_PREFIX,
-    PYDANTIC_V2,
     ModelNameMap,
     UnionType,
 )
diff --git a/aws_lambda_powertools/event_handler/openapi/models.py b/aws_lambda_powertools/event_handler/openapi/models.py
index bbbc160f1e6..ab97b6dc2e7 100644
--- a/aws_lambda_powertools/event_handler/openapi/models.py
+++ b/aws_lambda_powertools/event_handler/openapi/models.py
@@ -4,7 +4,7 @@
 from pydantic import AnyUrl, BaseModel, Field
 
 from aws_lambda_powertools.event_handler.openapi.compat import model_rebuild
-from aws_lambda_powertools.event_handler.openapi.types import PYDANTIC_V2
+from aws_lambda_powertools.event_handler.openapi.pydantic_loader import PYDANTIC_V2
 from aws_lambda_powertools.shared.types import Annotated, Literal
 
 """
diff --git a/aws_lambda_powertools/event_handler/openapi/params.py b/aws_lambda_powertools/event_handler/openapi/params.py
index 28154466ff6..f267a4841f5 100644
--- a/aws_lambda_powertools/event_handler/openapi/params.py
+++ b/aws_lambda_powertools/event_handler/openapi/params.py
@@ -15,7 +15,8 @@
     field_annotation_is_scalar,
     get_annotation_from_field_info,
 )
-from aws_lambda_powertools.event_handler.openapi.types import PYDANTIC_V2, CacheKey
+from aws_lambda_powertools.event_handler.openapi.pydantic_loader import PYDANTIC_V2
+from aws_lambda_powertools.event_handler.openapi.types import CacheKey
 from aws_lambda_powertools.shared.types import Annotated, Literal, get_args, get_origin
 
 """
diff --git a/aws_lambda_powertools/event_handler/openapi/pydantic_loader.py b/aws_lambda_powertools/event_handler/openapi/pydantic_loader.py
new file mode 100644
index 00000000000..12f06dad899
--- /dev/null
+++ b/aws_lambda_powertools/event_handler/openapi/pydantic_loader.py
@@ -0,0 +1,6 @@
+try:
+    from pydantic.version import VERSION as PYDANTIC_VERSION
+
+    PYDANTIC_V2 = PYDANTIC_VERSION.startswith("2.")
+except ImportError:
+    PYDANTIC_V2 = False
diff --git a/aws_lambda_powertools/event_handler/openapi/types.py b/aws_lambda_powertools/event_handler/openapi/types.py
index 9161d8dc170..0d166de1131 100644
--- a/aws_lambda_powertools/event_handler/openapi/types.py
+++ b/aws_lambda_powertools/event_handler/openapi/types.py
@@ -16,13 +16,6 @@
 COMPONENT_REF_TEMPLATE = "#/components/schemas/{model}"
 METHODS_WITH_BODY = {"GET", "HEAD", "POST", "PUT", "DELETE", "PATCH"}
 
-try:
-    from pydantic.version import VERSION as PYDANTIC_VERSION
-
-    PYDANTIC_V2 = PYDANTIC_VERSION.startswith("2.")
-except ImportError:
-    PYDANTIC_V2 = False
-
 
 validation_error_definition = {
     "title": "ValidationError",
diff --git a/tests/functional/event_handler/test_bedrock_agent.py b/tests/functional/event_handler/test_bedrock_agent.py
index 223f9bdbef1..df9fb66afc8 100644
--- a/tests/functional/event_handler/test_bedrock_agent.py
+++ b/tests/functional/event_handler/test_bedrock_agent.py
@@ -2,7 +2,7 @@
 from typing import Any, Dict
 
 from aws_lambda_powertools.event_handler import BedrockAgentResolver, Response, content_types
-from aws_lambda_powertools.event_handler.openapi.types import PYDANTIC_V2
+from aws_lambda_powertools.event_handler.openapi.pydantic_loader import PYDANTIC_V2
 from aws_lambda_powertools.utilities.data_classes import BedrockAgentEvent
 from tests.functional.utils import load_event