core: basemessage.text() (#29078)

libs/cli/langchain_cli/integration_template/integration_template/chat_models.py

@@ -86,7 +86,7 @@ class Chat__ModuleName__(BaseChatModel):
         .. code-block:: python
 
             for chunk in llm.stream(messages):
-                print(chunk)
+                print(chunk.text(), end="")
 
         .. code-block:: python
 

libs/core/langchain_core/messages/base.py

@@ -92,6 +92,27 @@ class BaseMessage(Serializable):
         """
         return ["langchain", "schema", "messages"]
 
+    def text(self) -> str:
+        """Get the text content of the message.
+
+        Returns:
+            The text content of the message.
+        """
+        if isinstance(self.content, str):
+            return self.content
+
+        # must be a list
+        blocks = [
+            block
+            for block in self.content
+            if isinstance(block, str)
+            or block.get("type") == "text"
+            and isinstance(block.get("text"), str)
+        ]
+        return "".join(
+            block if isinstance(block, str) else block["text"] for block in blocks
+        )
+
     def __add__(self, other: Any) -> ChatPromptTemplate:
         """Concatenate this message with another message."""
         from langchain_core.prompts.chat import ChatPromptTemplate

libs/core/tests/unit_tests/test_messages.py

@@ -1033,3 +1033,61 @@ def test_tool_message_tool_call_id() -> None:
     ToolMessage("foo", tool_call_id=uuid.uuid4())
     ToolMessage("foo", tool_call_id=1)
     ToolMessage("foo", tool_call_id=1.0)
+
+
+def test_message_text() -> None:
+    # partitions:
+    # message types: [ai], [human], [system], [tool]
+    # content types: [str], [list[str]], [list[dict]], [list[str | dict]]
+    # content: [empty], [single element], [multiple elements]
+    # content dict types: [text], [not text], [no type]
+
+    assert HumanMessage(content="foo").text() == "foo"
+    assert AIMessage(content=[]).text() == ""
+    assert AIMessage(content=["foo", "bar"]).text() == "foobar"
+    assert (
+        AIMessage(
+            content=[
+                {"type": "text", "text": "<thinking>thinking...</thinking>"},
+                {
+                    "type": "tool_use",
+                    "id": "toolu_01A09q90qw90lq917835lq9",
+                    "name": "get_weather",
+                    "input": {"location": "San Francisco, CA"},
+                },
+            ]
+        ).text()
+        == "<thinking>thinking...</thinking>"
+    )
+    assert (
+        SystemMessage(content=[{"type": "text", "text": "foo"}, "bar"]).text()
+        == "foobar"
+    )
+    assert (
+        ToolMessage(
+            content=[
+                {"type": "text", "text": "15 degrees"},
+                {
+                    "type": "image",
+                    "source": {
+                        "type": "base64",
+                        "media_type": "image/jpeg",
+                        "data": "/9j/4AAQSkZJRg...",
+                    },
+                },
+            ],
+            tool_call_id="1",
+        ).text()
+        == "15 degrees"
+    )
+    assert (
+        AIMessage(content=[{"text": "hi there"}, "hi"]).text() == "hi"
+    )  # missing type: text
+    assert AIMessage(content=[{"type": "nottext", "text": "hi"}]).text() == ""
+    assert AIMessage(content=[]).text() == ""
+    assert (
+        AIMessage(
+            content="", tool_calls=[create_tool_call(name="a", args={"b": 1}, id=None)]
+        ).text()
+        == ""
+    )

libs/partners/anthropic/langchain_anthropic/chat_models.py

@@ -368,7 +368,7 @@ class ChatAnthropic(BaseChatModel):
         .. code-block:: python
 
             for chunk in llm.stream(messages):
-                print(chunk)
+                print(chunk.text(), end="")
 
         .. code-block:: python
 

libs/partners/deepseek/langchain_deepseek/chat_models.py

@@ -70,7 +70,7 @@ class ChatDeepSeek(BaseChatOpenAI):
         .. code-block:: python
 
             for chunk in llm.stream(messages):
-                print(chunk)
+                print(chunk.text(), end="")
 
         .. code-block:: python
 

libs/partners/groq/langchain_groq/chat_models.py

@@ -172,7 +172,7 @@ class ChatGroq(BaseChatModel):
         .. code-block:: python
 
             for chunk in llm.stream(messages):
-                print(chunk)
+                print(chunk.text(), end="")
 
         .. code-block:: python
 

libs/partners/ollama/langchain_ollama/chat_models.py

@@ -228,7 +228,7 @@ class ChatOllama(BaseChatModel):
                 ("human", "Return the words Hello World!"),
             ]
             for chunk in llm.stream(messages):
-                print(chunk)
+                print(chunk.text(), end="")
 
 
         .. code-block:: python

libs/partners/openai/langchain_openai/chat_models/azure.py

@@ -183,7 +183,7 @@ class AzureChatOpenAI(BaseChatOpenAI):
         .. code-block:: python
 
             for chunk in llm.stream(messages):
-                print(chunk)
+                print(chunk.text(), end="")
 
         .. code-block:: python
 

libs/partners/openai/langchain_openai/chat_models/base.py

@@ -1616,7 +1616,7 @@ class ChatOpenAI(BaseChatOpenAI):  # type: ignore[override]
         .. code-block:: python
 
             for chunk in llm.stream(messages):
-                print(chunk)
+                print(chunk.text(), end="")
 
         .. code-block:: python
 

libs/partners/xai/langchain_xai/chat_models.py

@@ -90,7 +90,7 @@ class ChatXAI(BaseChatOpenAI):  # type: ignore[override]
         .. code-block:: python
 
             for chunk in llm.stream(messages):
-                print(chunk)
+                print(chunk.text(), end="")
 
         .. code-block:: python