fix: serialization of nested ChatMessage in GeneratedAnswerdataclass (#9497)

* Fix serialization

* small fix

* fix the erros

* Fix tests

* PR comments

Author: Amnah199

haystack/dataclasses/answer.py

@@ -6,7 +6,7 @@
 from typing import Any, Dict, List, Optional, Protocol, runtime_checkable
 
 from haystack.core.serialization import default_from_dict, default_to_dict
-from haystack.dataclasses.document import Document
+from haystack.dataclasses import ChatMessage, Document
 
 
 @runtime_checkable
@@ -99,7 +99,16 @@ def to_dict(self) -> Dict[str, Any]:
             Serialized dictionary representation of the object.
         """
         documents = [doc.to_dict(flatten=False) for doc in self.documents]
-        return default_to_dict(self, data=self.data, query=self.query, documents=documents, meta=self.meta)
+
+        # Serialize ChatMessage objects to dicts
+        meta = self.meta
+        all_messages = meta.get("all_messages")
+
+        # all_messages is either a list of ChatMessage objects or a list of strings
+        if all_messages and isinstance(all_messages[0], ChatMessage):
+            meta = {**meta, "all_messages": [msg.to_dict() for msg in all_messages]}
+
+        return default_to_dict(self, data=self.data, query=self.query, documents=documents, meta=meta)
 
     @classmethod
     def from_dict(cls, data: Dict[str, Any]) -> "GeneratedAnswer":
@@ -113,7 +122,13 @@ def from_dict(cls, data: Dict[str, Any]) -> "GeneratedAnswer":
             Deserialized object.
         """
         init_params = data.get("init_parameters", {})
+
         if (documents := init_params.get("documents")) is not None:
-            data["init_parameters"]["documents"] = [Document.from_dict(d) for d in documents]
+            init_params["documents"] = [Document.from_dict(d) for d in documents]
+
+        meta = init_params.get("meta", {})
+        if (all_messages := meta.get("all_messages")) is not None and isinstance(all_messages[0], dict):
+            meta["all_messages"] = [ChatMessage.from_dict(m) for m in all_messages]
+        init_params["meta"] = meta
 
         return default_from_dict(cls, data)

releasenotes/notes/fix-serialization-generated-answer-fa8f3692a184f8fd.yaml

@@ -0,0 +1,3 @@
+---
+fixes:
+  - Fix serialization of `GeneratedAnswer` when `ChatMessage` objects are nested in `meta`.

test/components/builders/test_answer_builder.py

@@ -52,6 +52,7 @@ def test_run_with_meta(self):
         assert answers[0].data == "reply1"
         _check_metadata_excluding_all_messages(answers[0].meta, {"test": "meta"})
         assert "all_messages" in answers[0].meta
+        assert answers[0].meta["all_messages"] == ["reply1"]
         assert answers[0].query == "query"
         assert answers[0].documents == []
         assert isinstance(answers[0], GeneratedAnswer)
@@ -254,6 +255,9 @@ def test_run_with_chat_message_replies_with_documents(self):
         assert answers[0].query == "test query"
         assert len(answers[0].documents) == 1
         assert answers[0].documents[0].content == "test doc 2"
+        assert answers[0].meta["all_messages"] == [
+            ChatMessage.from_assistant("Answer: AnswerString[2]", meta=message_meta)
+        ]
 
     def test_run_with_chat_message_replies_with_pattern_set_at_runtime(self):
         component = AnswerBuilder(pattern="unused pattern")

test/dataclasses/test_answer.py

@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: Apache-2.0
 
 from haystack.dataclasses.answer import Answer, ExtractedAnswer, GeneratedAnswer
-from haystack.dataclasses.document import Document
+from haystack.dataclasses import Document, ChatMessage
 
 
 class TestExtractedAnswer:
@@ -133,25 +133,85 @@ def test_protocol(self):
         assert isinstance(answer, Answer)
 
     def test_to_dict(self):
+        answer = GeneratedAnswer(data="42", query="What is the answer?", documents=[])
+        assert answer.to_dict() == {
+            "type": "haystack.dataclasses.answer.GeneratedAnswer",
+            "init_parameters": {"data": "42", "query": "What is the answer?", "documents": [], "meta": {}},
+        }
+
+    def test_to_dict_with_meta(self):
+        answer = GeneratedAnswer(
+            data="42",
+            query="What is the answer?",
+            documents=[],
+            meta={"meta_key": "meta_value", "all_messages": ["What is the answer?"]},
+        )
+        assert answer.to_dict() == {
+            "type": "haystack.dataclasses.answer.GeneratedAnswer",
+            "init_parameters": {
+                "data": "42",
+                "query": "What is the answer?",
+                "documents": [],
+                "meta": {"meta_key": "meta_value", "all_messages": ["What is the answer?"]},
+            },
+        }
+
+    def test_to_dict_with_chat_message_in_meta(self):
         documents = [
             Document(id="1", content="The answer is 42."),
             Document(id="2", content="I believe the answer is 42."),
             Document(id="3", content="42 is definitely the answer."),
         ]
         answer = GeneratedAnswer(
-            data="42", query="What is the answer?", documents=documents, meta={"meta_key": "meta_value"}
+            data="42",
+            query="What is the answer?",
+            documents=documents,
+            meta={"meta_key": "meta_value", "all_messages": [ChatMessage.from_user("What is the answer?")]},
         )
         assert answer.to_dict() == {
             "type": "haystack.dataclasses.answer.GeneratedAnswer",
             "init_parameters": {
                 "data": "42",
                 "query": "What is the answer?",
                 "documents": [d.to_dict(flatten=False) for d in documents],
-                "meta": {"meta_key": "meta_value"},
+                "meta": {
+                    "meta_key": "meta_value",
+                    "all_messages": [ChatMessage.from_user("What is the answer?").to_dict()],
+                },
             },
         }
 
     def test_from_dict(self):
+        answer = GeneratedAnswer.from_dict(
+            {
+                "type": "haystack.dataclasses.answer.GeneratedAnswer",
+                "init_parameters": {"data": "42", "query": "What is the answer?", "documents": [], "meta": {}},
+            }
+        )
+        assert answer.data == "42"
+        assert answer.query == "What is the answer?"
+        assert answer.documents == []
+        assert answer.meta == {}
+
+    def test_from_dict_with_meta(self):
+        answer = GeneratedAnswer.from_dict(
+            {
+                "type": "haystack.dataclasses.answer.GeneratedAnswer",
+                "init_parameters": {
+                    "data": "42",
+                    "query": "What is the answer?",
+                    "documents": [],
+                    "meta": {"meta_key": "meta_value", "all_messages": ["What is the answer?"]},
+                },
+            }
+        )
+        assert answer.data == "42"
+        assert answer.query == "What is the answer?"
+        assert answer.documents == []
+        assert answer.meta["meta_key"] == "meta_value"
+        assert answer.meta["all_messages"] == ["What is the answer?"]
+
+    def test_from_dict_with_chat_message_in_meta(self):
         answer = GeneratedAnswer.from_dict(
             {
                 "type": "haystack.dataclasses.answer.GeneratedAnswer",
@@ -163,7 +223,10 @@ def test_from_dict(self):
                         {"id": "2", "content": "I believe the answer is 42."},
                         {"id": "3", "content": "42 is definitely the answer."},
                     ],
-                    "meta": {"meta_key": "meta_value"},
+                    "meta": {
+                        "meta_key": "meta_value",
+                        "all_messages": [ChatMessage.from_user("What is the answer?").to_dict()],
+                    },
                 },
             }
         )
@@ -174,4 +237,5 @@ def test_from_dict(self):
             Document(id="2", content="I believe the answer is 42."),
             Document(id="3", content="42 is definitely the answer."),
         ]
-        assert answer.meta == {"meta_key": "meta_value"}
+        assert answer.meta["meta_key"] == "meta_value"
+        assert answer.meta["all_messages"] == [ChatMessage.from_user("What is the answer?")]