DynamoDB: transact_write_items() now validates empty ExpressionAttrib…

moto/dynamodb/exceptions.py

@@ -121,6 +121,11 @@ def __init__(self, attribute_value: str):
         )
 
 
+class ExpressionAttributeValuesEmpty(MockValidationException):
+    def __init__(self) -> None:
+        super().__init__("ExpressionAttributeValues must not be empty")
+
+
 class UpdateExprSyntaxError(InvalidUpdateExpression):
     update_expr_syntax_error_msg = "Syntax error; {error_detail}"
 

moto/dynamodb/responses.py

@@ -14,6 +14,7 @@
 from moto.utilities.aws_headers import amz_crc32
 
 from .exceptions import (
+    ExpressionAttributeValuesEmpty,
     InvalidProjectionExpression,
     KeyIsEmptyStringException,
     MockValidationException,
@@ -1012,7 +1013,7 @@ def _get_expr_attr_values(self) -> Dict[str, Dict[str, str]]:
         if values is None:
             return {}
         if len(values) == 0:
-            raise MockValidationException("ExpressionAttributeValues must not be empty")
+            raise ExpressionAttributeValuesEmpty
         for key in values.keys():
             if not key.startswith(":"):
                 raise MockValidationException(
@@ -1134,10 +1135,16 @@ def transact_write_items(self) -> str:
         # Validate first - we should error before we start the transaction
         for item in transact_items:
             if "Put" in item:
+                if item["Put"].get("ExpressionAttributeValues") == {}:
+                    raise ExpressionAttributeValuesEmpty
+
                 item_attrs = item["Put"]["Item"]
                 table = self.dynamodb_backend.get_table(item["Put"]["TableName"])
                 validate_put_has_empty_keys(item_attrs, table)
             if "Update" in item:
+                if item["Update"].get("ExpressionAttributeValues") == {}:
+                    raise ExpressionAttributeValuesEmpty
+
                 item_attrs = item["Update"]["Key"]
                 table = self.dynamodb_backend.get_table(item["Update"]["TableName"])
                 validate_put_has_empty_keys(

tests/test_dynamodb/exceptions/test_dynamodb_transactions.py

@@ -273,3 +273,45 @@ def test_transaction_with_empty_key(table_name=None):
         err["Message"]
         == "One or more parameter values are not valid. The AttributeValue for a key attribute cannot contain an empty string value. Key: pk"
     )
+
+
+@pytest.mark.aws_verified
+@dynamodb_aws_verified()
+def test_transact_write_items__empty_expr_attr_values(table_name=None):
+    dynamodb = boto3.client("dynamodb", region_name="us-east-1")
+
+    with pytest.raises(ClientError) as exc:
+        dynamodb.transact_write_items(
+            TransactItems=[
+                {
+                    "Put": {
+                        "Item": {"pk": {"S": "tenant#0000001-tenant#0000001"}},
+                        "ConditionExpression": "attribute_not_exists(#n0)",
+                        "TableName": table_name,
+                        "ExpressionAttributeNames": {"#n0": "pk"},
+                        "ExpressionAttributeValues": {},
+                    }
+                },
+            ]
+        )
+    err = exc.value.response["Error"]
+    assert err["Code"] == "ValidationException"
+    assert err["Message"] == "ExpressionAttributeValues must not be empty"
+
+    with pytest.raises(ClientError) as exc:
+        dynamodb.transact_write_items(
+            TransactItems=[
+                {
+                    "Update": {
+                        "Key": {"pk": {"S": "globals"}},
+                        "UpdateExpression": "SET #0 = {'S': 'asdf'}",
+                        "ExpressionAttributeNames": {"#0": "tenant_count"},
+                        "ExpressionAttributeValues": {},
+                        "TableName": table_name,
+                    }
+                },
+            ]
+        )
+    err = exc.value.response["Error"]
+    assert err["Code"] == "ValidationException"
+    assert err["Message"] == "ExpressionAttributeValues must not be empty"