feat: made truncation optional for BedrockGenerator (#833)

* Added truncate parameter to init method

* fixed serialization bug for BedrockGenerator

* Add a test to check truncation functionality

integrations/amazon_bedrock/src/haystack_integrations/components/generators/amazon_bedrock/generator.py

@@ -75,6 +75,7 @@ def __init__(
         aws_region_name: Optional[Secret] = Secret.from_env_var("AWS_DEFAULT_REGION", strict=False),  # noqa: B008
         aws_profile_name: Optional[Secret] = Secret.from_env_var("AWS_PROFILE", strict=False),  # noqa: B008
         max_length: Optional[int] = 100,
+        truncate: Optional[bool] = True,
         **kwargs,
     ):
         """
@@ -87,6 +88,7 @@ def __init__(
         :param aws_region_name: The AWS region name.
         :param aws_profile_name: The AWS profile name.
         :param max_length: The maximum length of the generated text.
+        :param truncate: Whether to truncate the prompt or not.
         :param kwargs: Additional keyword arguments to be passed to the model.
         :raises ValueError: If the model name is empty or None.
         :raises AmazonBedrockConfigurationError: If the AWS environment is not configured correctly or the model is
@@ -97,11 +99,13 @@ def __init__(
             raise ValueError(msg)
         self.model = model
         self.max_length = max_length
+        self.truncate = truncate
         self.aws_access_key_id = aws_access_key_id
         self.aws_secret_access_key = aws_secret_access_key
         self.aws_session_token = aws_session_token
         self.aws_region_name = aws_region_name
         self.aws_profile_name = aws_profile_name
+        self.kwargs = kwargs
 
         def resolve_secret(secret: Optional[Secret]) -> Optional[str]:
             return secret.resolve_value() if secret else None
@@ -129,6 +133,7 @@ def resolve_secret(secret: Optional[Secret]) -> Optional[str]:
         # Truncate prompt if prompt tokens > model_max_length-max_length
         # (max_length is the length of the generated text)
         # we use GPT2 tokenizer which will likely provide good token count approximation
+
         self.prompt_handler = DefaultPromptHandler(
             tokenizer="gpt2",
             model_max_length=model_max_length,
@@ -189,6 +194,9 @@ def invoke(self, *args, **kwargs):
             )
             raise ValueError(msg)
 
+        if self.truncate:
+            prompt = self._ensure_token_limit(prompt)
+
         body = self.model_adapter.prepare_body(prompt=prompt, **kwargs)
         try:
             if stream:
@@ -266,6 +274,8 @@ def to_dict(self) -> Dict[str, Any]:
             aws_profile_name=self.aws_profile_name.to_dict() if self.aws_profile_name else None,
             model=self.model,
             max_length=self.max_length,
+            truncate=self.truncate,
+            **self.kwargs,
         )
 
     @classmethod

integrations/amazon_bedrock/tests/test_generator.py

@@ -20,10 +20,7 @@ def test_to_dict(mock_boto3_session):
     """
     Test that the to_dict method returns the correct dictionary without aws credentials
     """
-    generator = AmazonBedrockGenerator(
-        model="anthropic.claude-v2",
-        max_length=99,
-    )
+    generator = AmazonBedrockGenerator(model="anthropic.claude-v2", max_length=99, truncate=False, temperature=10)
 
     expected_dict = {
         "type": "haystack_integrations.components.generators.amazon_bedrock.generator.AmazonBedrockGenerator",
@@ -35,6 +32,8 @@ def test_to_dict(mock_boto3_session):
             "aws_profile_name": {"type": "env_var", "env_vars": ["AWS_PROFILE"], "strict": False},
             "model": "anthropic.claude-v2",
             "max_length": 99,
+            "truncate": False,
+            "temperature": 10,
         },
     }
 
@@ -194,6 +193,46 @@ def test_long_prompt_is_truncated(mock_boto3_session):
     assert prompt_after_resize == truncated_prompt_text
 
 
+def test_long_prompt_is_not_truncated_when_truncate_false(mock_boto3_session):
+    """
+    Test that a long prompt is not truncated and _ensure_token_limit is not called when truncate is set to False
+    """
+    long_prompt_text = "I am a tokenized prompt of length eight"
+
+    # Our mock prompt is 8 tokens long, so it exceeds the total limit (8 prompt tokens + 3 generated tokens > 10 tokens)
+    max_length_generated_text = 3
+    total_model_max_length = 10
+
+    with patch("transformers.AutoTokenizer.from_pretrained", return_value=MagicMock()):
+        generator = AmazonBedrockGenerator(
+            model="anthropic.claude-v2",
+            max_length=max_length_generated_text,
+            model_max_length=total_model_max_length,
+            truncate=False,
+        )
+
+        # Mock the _ensure_token_limit method to track if it is called
+        with patch.object(
+            generator, "_ensure_token_limit", wraps=generator._ensure_token_limit
+        ) as mock_ensure_token_limit:
+            # Mock the model adapter to avoid actual invocation
+            generator.model_adapter.prepare_body = MagicMock(return_value={})
+            generator.client = MagicMock()
+            generator.client.invoke_model = MagicMock(
+                return_value={"body": MagicMock(read=MagicMock(return_value=b'{"generated_text": "response"}'))}
+            )
+            generator.model_adapter.get_responses = MagicMock(return_value=["response"])
+
+            # Invoke the generator
+            generator.invoke(prompt=long_prompt_text)
+
+        # Ensure _ensure_token_limit was not called
+        mock_ensure_token_limit.assert_not_called(),
+
+        # Check the prompt passed to prepare_body
+        generator.model_adapter.prepare_body.assert_called_with(prompt=long_prompt_text)
+
+
 @pytest.mark.parametrize(
     "model, expected_model_adapter",
     [