fix: Allow event_key_jmespath to be left empty to use entire event as payload

Author: Tom McCarthy

aws_lambda_powertools/utilities/idempotency/persistence/base.py

@@ -114,7 +114,7 @@ class BasePersistenceLayer(ABC):
 
     def __init__(
         self,
-        event_key_jmespath: str,
+        event_key_jmespath: str = "",
         payload_validation_jmespath: str = "",
         expires_after_seconds: int = 60 * 60,  # 1 hour default
         use_local_cache: bool = False,
@@ -140,7 +140,8 @@ def __init__(
             Function to use for calculating hashes, by default md5.
         """
         self.event_key_jmespath = event_key_jmespath
-        self.event_key_compiled_jmespath = jmespath.compile(event_key_jmespath)
+        if self.event_key_jmespath:
+            self.event_key_compiled_jmespath = jmespath.compile(event_key_jmespath)
         self.expires_after_seconds = expires_after_seconds
         self.use_local_cache = use_local_cache
         if self.use_local_cache:
@@ -166,7 +167,9 @@ def _get_hashed_idempotency_key(self, lambda_event: Dict[str, Any]) -> str:
             Hashed representation of the data extracted by the jmespath expression
 
         """
-        data = self.event_key_compiled_jmespath.search(lambda_event)
+        data = lambda_event
+        if self.event_key_jmespath:
+            data = self.event_key_compiled_jmespath.search(lambda_event)
         return self._generate_hash(data)
 
     def _get_hashed_payload(self, lambda_event: Dict[str, Any]) -> str:

docs/utilities/idempotency.md

@@ -66,12 +66,12 @@ Resources:
 ### Lambda handler
 
 You can quickly start by initializing the `DynamoDBPersistenceLayer` class outside the Lambda handler, and using it
-with the `idempotent` decorator on your lambda handler. There are 2 required parameters to initialize the persistence
-layer:
+with the `idempotent` decorator on your lambda handler. The only required parameter is `table_name`, but you likely
+want to specify `event_key_jmespath` as well.
 
-`table_name`: The name of the DynamoDB table to use.
 `event_key_jmespath`: A JMESpath expression which will be used to extract the payload from the event your Lambda hander
-is called with. This payload will be used as the key to decide if future invocations are duplicates.
+is called with. This payload will be used as the key to decide if future invocations are duplicates. If you don't pass
+this parameter, the entire event will be used as the key.
 
 === "app.py"