chore: use class methods to create ChatMessage (#8581)

* use class methods to build messages

* fix failing format

Author: anakin87

Diff for: haystack/core/pipeline/base.py

@@ -183,7 +183,8 @@ def from_dict(
                         "Component was deserialized with the following data:"
                         f"{str(component_data)}."
                         "Possible reasons include malformed serialized data, mismatch between the serialized component "
-                        "and the loaded one (due to a breaking change, see  https://github.com/deepset-ai/haystack/releases), etc."
+                        "and the loaded one (due to a breaking change, see "
+                        "https://github.com/deepset-ai/haystack/releases), etc."
                     )
                     raise DeserializationError(msg) from error
             pipe.add_component(name=name, instance=instance)

Diff for: releasenotes/notes/chatmessage-use-class-methods-85a30b0c5512b08c.yaml

@@ -0,0 +1,5 @@
+---
+enhancements:
+  - |
+    Across Haystack codebase, we have replaced the use of `ChatMessage` dataclass constructor with specific
+    class methods (`ChatMessage.from_user`, `ChatMessage.from_assistant`, etc.).

Diff for: test/components/builders/test_answer_builder.py

@@ -164,77 +164,54 @@ def test_run_with_reference_pattern_set_at_runtime(self):
 
     def test_run_with_chat_message_replies_without_pattern(self):
         component = AnswerBuilder()
-        replies = [
-            ChatMessage(
-                content="Answer: AnswerString",
-                role=ChatRole.ASSISTANT,
-                name=None,
-                meta={
-                    "model": "gpt-4o-mini",
-                    "index": 0,
-                    "finish_reason": "stop",
-                    "usage": {"prompt_tokens": 32, "completion_tokens": 153, "total_tokens": 185},
-                },
-            )
-        ]
-        output = component.run(query="test query", replies=replies, meta=[{}])
-        answers = output["answers"]
-        assert len(answers) == 1
-        assert answers[0].data == "Answer: AnswerString"
-        assert answers[0].meta == {
+
+        message_meta = {
             "model": "gpt-4o-mini",
             "index": 0,
             "finish_reason": "stop",
             "usage": {"prompt_tokens": 32, "completion_tokens": 153, "total_tokens": 185},
         }
+        replies = [ChatMessage.from_assistant("Answer: AnswerString", meta=message_meta)]
+
+        output = component.run(query="test query", replies=replies, meta=[{}])
+        answers = output["answers"]
+        assert len(answers) == 1
+        assert answers[0].data == "Answer: AnswerString"
+        assert answers[0].meta == message_meta
         assert answers[0].query == "test query"
         assert answers[0].documents == []
         assert isinstance(answers[0], GeneratedAnswer)
 
     def test_run_with_chat_message_replies_with_pattern(self):
         component = AnswerBuilder(pattern=r"Answer: (.*)")
-        replies = [
-            ChatMessage(
-                content="Answer: AnswerString",
-                role=ChatRole.ASSISTANT,
-                name=None,
-                meta={
-                    "model": "gpt-4o-mini",
-                    "index": 0,
-                    "finish_reason": "stop",
-                    "usage": {"prompt_tokens": 32, "completion_tokens": 153, "total_tokens": 185},
-                },
-            )
-        ]
-        output = component.run(query="test query", replies=replies, meta=[{}])
-        answers = output["answers"]
-        assert len(answers) == 1
-        assert answers[0].data == "AnswerString"
-        assert answers[0].meta == {
+
+        message_meta = {
             "model": "gpt-4o-mini",
             "index": 0,
             "finish_reason": "stop",
             "usage": {"prompt_tokens": 32, "completion_tokens": 153, "total_tokens": 185},
         }
+        replies = [ChatMessage.from_assistant("Answer: AnswerString", meta=message_meta)]
+
+        output = component.run(query="test query", replies=replies, meta=[{}])
+        answers = output["answers"]
+        assert len(answers) == 1
+        assert answers[0].data == "AnswerString"
+        assert answers[0].meta == message_meta
         assert answers[0].query == "test query"
         assert answers[0].documents == []
         assert isinstance(answers[0], GeneratedAnswer)
 
     def test_run_with_chat_message_replies_with_documents(self):
         component = AnswerBuilder(reference_pattern="\\[(\\d+)\\]")
-        replies = [
-            ChatMessage(
-                content="Answer: AnswerString[2]",
-                role=ChatRole.ASSISTANT,
-                name=None,
-                meta={
-                    "model": "gpt-4o-mini",
-                    "index": 0,
-                    "finish_reason": "stop",
-                    "usage": {"prompt_tokens": 32, "completion_tokens": 153, "total_tokens": 185},
-                },
-            )
-        ]
+        message_meta = {
+            "model": "gpt-4o-mini",
+            "index": 0,
+            "finish_reason": "stop",
+            "usage": {"prompt_tokens": 32, "completion_tokens": 153, "total_tokens": 185},
+        }
+        replies = [ChatMessage.from_assistant("Answer: AnswerString[2]", meta=message_meta)]
+
         output = component.run(
             query="test query",
             replies=replies,
@@ -244,60 +221,40 @@ def test_run_with_chat_message_replies_with_documents(self):
         answers = output["answers"]
         assert len(answers) == 1
         assert answers[0].data == "Answer: AnswerString[2]"
-        assert answers[0].meta == {
-            "model": "gpt-4o-mini",
-            "index": 0,
-            "finish_reason": "stop",
-            "usage": {"prompt_tokens": 32, "completion_tokens": 153, "total_tokens": 185},
-        }
+        assert answers[0].meta == message_meta
         assert answers[0].query == "test query"
         assert len(answers[0].documents) == 1
         assert answers[0].documents[0].content == "test doc 2"
 
     def test_run_with_chat_message_replies_with_pattern_set_at_runtime(self):
         component = AnswerBuilder(pattern="unused pattern")
-        replies = [
-            ChatMessage(
-                content="Answer: AnswerString",
-                role=ChatRole.ASSISTANT,
-                name=None,
-                meta={
-                    "model": "gpt-4o-mini",
-                    "index": 0,
-                    "finish_reason": "stop",
-                    "usage": {"prompt_tokens": 32, "completion_tokens": 153, "total_tokens": 185},
-                },
-            )
-        ]
-        output = component.run(query="test query", replies=replies, meta=[{}], pattern=r"Answer: (.*)")
-        answers = output["answers"]
-        assert len(answers) == 1
-        assert answers[0].data == "AnswerString"
-        assert answers[0].meta == {
+        message_meta = {
             "model": "gpt-4o-mini",
             "index": 0,
             "finish_reason": "stop",
             "usage": {"prompt_tokens": 32, "completion_tokens": 153, "total_tokens": 185},
         }
+        replies = [ChatMessage.from_assistant("Answer: AnswerString", meta=message_meta)]
+
+        output = component.run(query="test query", replies=replies, meta=[{}], pattern=r"Answer: (.*)")
+        answers = output["answers"]
+        assert len(answers) == 1
+        assert answers[0].data == "AnswerString"
+        assert answers[0].meta == message_meta
         assert answers[0].query == "test query"
         assert answers[0].documents == []
         assert isinstance(answers[0], GeneratedAnswer)
 
     def test_run_with_chat_message_replies_with_meta_set_at_run_time(self):
         component = AnswerBuilder()
-        replies = [
-            ChatMessage(
-                content="AnswerString",
-                role=ChatRole.ASSISTANT,
-                name=None,
-                meta={
-                    "model": "gpt-4o-mini",
-                    "index": 0,
-                    "finish_reason": "stop",
-                    "usage": {"prompt_tokens": 32, "completion_tokens": 153, "total_tokens": 185},
-                },
-            )
-        ]
+        message_meta = {
+            "model": "gpt-4o-mini",
+            "index": 0,
+            "finish_reason": "stop",
+            "usage": {"prompt_tokens": 32, "completion_tokens": 153, "total_tokens": 185},
+        }
+        replies = [ChatMessage.from_assistant("AnswerString", meta=message_meta)]
+
         output = component.run(query="test query", replies=replies, meta=[{"test": "meta"}])
         answers = output["answers"]
         assert len(answers) == 1
@@ -315,8 +272,9 @@ def test_run_with_chat_message_replies_with_meta_set_at_run_time(self):
 
     def test_run_with_chat_message_no_meta_with_meta_set_at_run_time(self):
         component = AnswerBuilder()
-        replies = [ChatMessage(content="AnswerString", role=ChatRole.ASSISTANT, name=None, meta={})]
+        replies = [ChatMessage.from_assistant("AnswerString")]
         output = component.run(query="test query", replies=replies, meta=[{"test": "meta"}])
+
         answers = output["answers"]
         assert len(answers) == 1
         assert answers[0].data == "AnswerString"

Diff for: test/components/builders/test_chat_prompt_builder.py

@@ -210,11 +210,14 @@ def test_run_with_meta(self):
         Test that the ChatPromptBuilder correctly handles meta data.
         It should render the message and copy the meta data from the original message.
         """
-        m = ChatMessage(content="This is a {{ variable }}", role=ChatRole.USER, name=None, meta={"test": "test"})
+        m = ChatMessage.from_user("This is a {{ variable }}")
+        m.meta["meta_field"] = "meta_value"
         builder = ChatPromptBuilder(template=[m])
         res = builder.run(variable="test")
-        res_msg = ChatMessage(content="This is a test", role=ChatRole.USER, name=None, meta={"test": "test"})
-        assert res == {"prompt": [res_msg]}
+
+        expected_msg = ChatMessage.from_user("This is a test")
+        expected_msg.meta["meta_field"] = "meta_value"
+        assert res == {"prompt": [expected_msg]}
 
     def test_run_with_invalid_template(self):
         builder = ChatPromptBuilder()

Diff for: test/dataclasses/test_chat_message.py

@@ -96,12 +96,12 @@ def test_to_dict():
 
 
 def test_from_dict():
-    assert ChatMessage.from_dict(data={"content": "text", "role": "user", "name": None}) == ChatMessage(
-        content="text", role=ChatRole("user"), name=None, meta={}
+    assert ChatMessage.from_dict(data={"content": "text", "role": "user", "name": None}) == ChatMessage.from_user(
+        "text"
     )
 
 
 def test_from_dict_with_meta():
     assert ChatMessage.from_dict(
-        data={"content": "text", "role": "user", "name": None, "meta": {"something": "something"}}
-    ) == ChatMessage(content="text", role=ChatRole("user"), name=None, meta={"something": "something"})
+        data={"content": "text", "role": "assistant", "name": None, "meta": {"something": "something"}}
+    ) == ChatMessage.from_assistant("text", meta={"something": "something"})