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feat: improve AnswerBuilder to support showing RAG references (#9933)

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* draft

* improve

* refactor

* improvs + usage ex

* relnote

* pipeline test fix
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Stefano Fiorucci 2025-10-24 12:47:16 +02:00 committed by GitHub
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110
haystack/components/builders/answer_builder.py
View File

@ -3,6 +3,7 @@
# SPDX-License-Identifier: Apache-2.0
import re
from dataclasses import replace
from typing import Any, Optional, Union
from haystack import Document, GeneratedAnswer, component, logging
@ -29,10 +30,50 @@ class AnswerBuilder:
builder = AnswerBuilder(pattern="Answer: (.*)")
builder.run(query="What's the answer?", replies=["This is an argument. Answer: This is the answer."])
```
### Usage example with documents and reference pattern
```python
from haystack import Document
from haystack.components.builders import AnswerBuilder
replies = ["The capital of France is Paris [2]."]
docs = [
Document(content="Berlin is the capital of Germany."),
Document(content="Paris is the capital of France."),
Document(content="Rome is the capital of Italy."),
]
builder = AnswerBuilder(reference_pattern="\\[(\\d+)\\]", return_only_referenced_documents=False)
result = builder.run(query="What is the capital of France?", replies=replies, documents=docs)["answers"][0]
print(f"Answer: {result.data}")
print("References:")
for doc in result.documents:
if doc.meta["referenced"]:
print(f"[{doc.meta['source_index']}] {doc.content}")
print("Other sources:")
for doc in result.documents:
if not doc.meta["referenced"]:
print(f"[{doc.meta['source_index']}] {doc.content}")
# Answer: The capital of France is Paris
# References:
# [2] Paris is the capital of France.
# Other sources:
# [1] Berlin is the capital of Germany.
# [3] Rome is the capital of Italy.
```
"""
def __init__(
self, pattern: Optional[str] = None, reference_pattern: Optional[str] = None, last_message_only: bool = False
self,
pattern: Optional[str] = None,
reference_pattern: Optional[str] = None,
last_message_only: bool = False,
*,
return_only_referenced_documents: bool = True,
):
"""
Creates an instance of the AnswerBuilder component.
@ -49,13 +90,20 @@ class AnswerBuilder:
:param reference_pattern:
The regular expression pattern used for parsing the document references.
If not specified, no parsing is done, and all documents are referenced.
If not specified, no parsing is done, and all documents are returned.
References need to be specified as indices of the input documents and start at [1].
Example: `\\[(\\d+)\\]` finds "1" in a string "this is an answer[1]".
If this parameter is provided, documents metadata will contain a "referenced" key with a boolean value.
:param last_message_only:
If False (default value), all messages are used as the answer.
If True, only the last message is used as the answer.
:param return_only_referenced_documents:
To be used in conjunction with `reference_pattern`.
If True (default value), only the documents that were actually referenced in `replies` are returned.
If False, all documents are returned.
If `reference_pattern` is not provided, this parameter has no effect, and all documents are returned.
"""
if pattern:
AnswerBuilder._check_num_groups_in_regex(pattern)
@ -63,6 +111,7 @@ class AnswerBuilder:
self.pattern = pattern
self.reference_pattern = reference_pattern
self.last_message_only = last_message_only
self.return_only_referenced_documents = return_only_referenced_documents
@component.output_types(answers=list[GeneratedAnswer])
def run( # pylint: disable=too-many-positional-arguments
@ -85,9 +134,12 @@ class AnswerBuilder:
The metadata returned by the Generator. If not specified, the generated answer will contain no metadata.
:param documents:
The documents used as the Generator inputs. If specified, they are added to
the`GeneratedAnswer` objects.
If both `documents` and `reference_pattern` are specified, the documents referenced in the
Generator output are extracted from the input documents and added to the `GeneratedAnswer` objects.
the `GeneratedAnswer` objects.
Each Document.meta includes a "source_index" key, representing its 1-based position in the input list.
When `reference_pattern` is provided:
- "referenced" key is added to the Document.meta, indicating if the document was referenced in the output.
- `return_only_referenced_documents` init parameter controls if all or only referenced documents are
returned.
:param pattern:
The regular expression pattern to extract the answer text from the Generator.
If not specified, the entire response is used as the answer.
@ -100,7 +152,7 @@ class AnswerBuilder:
"this is an argument. Answer: this is an answer".
:param reference_pattern:
The regular expression pattern used for parsing the document references.
If not specified, no parsing is done, and all documents are referenced.
If not specified, no parsing is done, and all documents are returned.
References need to be specified as indices of the input documents and start at [1].
Example: `\\[(\\d+)\\]` finds "1" in a string "this is an answer[1]".
@ -117,21 +169,14 @@ class AnswerBuilder:
pattern = pattern or self.pattern
reference_pattern = reference_pattern or self.reference_pattern
replies_to_iterate = replies[-1:] if self.last_message_only and replies else replies
meta_to_iterate = meta[-1:] if self.last_message_only and meta else meta
all_answers = []
replies_to_iterate = replies
meta_to_iterate = meta
if self.last_message_only and replies:
replies_to_iterate = replies[-1:]
meta_to_iterate = meta[-1:]
for reply, given_metadata in zip(replies_to_iterate, meta_to_iterate):
# Extract content from ChatMessage objects if reply is a ChatMessages, else use the string as is
if isinstance(reply, ChatMessage):
extracted_reply = reply.text or ""
else:
extracted_reply = str(reply)
extracted_reply = reply.text or "" if isinstance(reply, ChatMessage) else str(reply)
extracted_metadata = reply.meta if isinstance(reply, ChatMessage) else {}
extracted_metadata = {**extracted_metadata, **given_metadata}
@ -139,18 +184,31 @@ class AnswerBuilder:
referenced_docs = []
if documents:
if reference_pattern:
reference_idxs = AnswerBuilder._extract_reference_idxs(extracted_reply, reference_pattern)
else:
reference_idxs = [doc_idx for doc_idx, _ in enumerate(documents)]
referenced_idxs = (
AnswerBuilder._extract_reference_idxs(extracted_reply, reference_pattern)
if reference_pattern
else set()
)
doc_idxs = (
referenced_idxs
if reference_pattern and self.return_only_referenced_documents
else set(range(len(documents)))
)
for idx in reference_idxs:
for idx in doc_idxs:
try:
referenced_docs.append(documents[idx])
doc = documents[idx]
except IndexError:
logger.warning(
"Document index '{index}' referenced in Generator output is out of range. ", index=idx + 1
)
continue
doc_meta: dict[str, Any] = doc.meta or {}
doc_meta["source_index"] = idx + 1
if reference_pattern:
doc_meta["referenced"] = idx in referenced_idxs
referenced_docs.append(replace(doc, meta=doc_meta))
answer_string = AnswerBuilder._extract_answer_string(extracted_reply, pattern)
answer = GeneratedAnswer(
@ -184,9 +242,9 @@ class AnswerBuilder:
return ""
@staticmethod
def _extract_reference_idxs(reply: str, reference_pattern: str) -> list[int]:
def _extract_reference_idxs(reply: str, reference_pattern: str) -> set[int]:
document_idxs = re.findall(reference_pattern, reply)
return [int(idx) - 1 for idx in document_idxs]
return {int(idx) - 1 for idx in document_idxs}
@staticmethod
def _check_num_groups_in_regex(pattern: str):

10
releasenotes/notes/answer-builder-refactoring-dc02d2285aebea32.yaml Normal file
View File

@ -0,0 +1,10 @@
---
features:
- |
The `AnswerBuilder` component now exposes a new parameter `return_only_referenced_documents` (default: True) that
controls if only documents referenced in the `replies` are returned.
Returned documents include two new fields in the `meta` dictionary:
- `source_index`: the 1-based index of the document in the input list
- `referenced`: a boolean value indicating if the document was referenced in the `replies` (only present
if the `reference_pattern` parameter is provided).
These additions make it easier to display references and other sources within a RAG pipeline.

24
test/components/builders/test_answer_builder.py
View File

@ -143,6 +143,30 @@ class TestAnswerBuilder:
assert answers[0].query == "test query"
assert len(answers[0].documents) == 1
assert answers[0].documents[0].content == "test doc 2"
assert answers[0].documents[0].meta["referenced"] is True
assert answers[0].documents[0].meta["source_index"] == 2
def test_run_with_documents_with_reference_pattern_return_all_documents(self):
component = AnswerBuilder(reference_pattern="\\[(\\d+)\\]", return_only_referenced_documents=False)
output = component.run(
query="test query",
replies=["Answer: AnswerString[2]"],
meta=[{}],
documents=[Document(content="test doc 1"), Document(content="test doc 2")],
)
answers = output["answers"]
assert len(answers) == 1
assert answers[0].data == "Answer: AnswerString[2]"
_check_metadata_excluding_all_messages(answers[0].meta, {})
assert "all_messages" in answers[0].meta
assert answers[0].query == "test query"
assert len(answers[0].documents) == 2
assert answers[0].documents[0].content == "test doc 1"
assert answers[0].documents[0].meta["referenced"] is False
assert answers[0].documents[0].meta["source_index"] == 1
assert answers[0].documents[1].content == "test doc 2"
assert answers[0].documents[1].meta["referenced"] is True
assert answers[0].documents[1].meta["source_index"] == 2
def test_run_with_documents_with_reference_pattern_and_no_match(self, caplog):
component = AnswerBuilder(reference_pattern="\\[(\\d+)\\]")

2
test/core/pipeline/features/test_run.py
View File

@ -951,11 +951,13 @@ def pipeline_that_has_a_component_with_only_default_inputs(pipeline_class):
id="413dccdf51a54cca75b7ed2eddac04e6e58560bd2f0caf4106a3efc023fe3651",
content="Paris is the capital of France",
score=1.600237583702734,
meta={"source_index": 1},
),
Document(
id="a4a874fc2ef75015da7924d709fbdd2430e46a8e94add6e0f26cd32c1c03435d",
content="Rome is the capital of Italy",
score=1.2536639934227616,
meta={"source_index": 2},
),
],
meta={"all_messages": ["Paris"]},