Convert a sequence of messages to strings and concatenate them into one string.
get_buffer_string(
messages: Sequence[BaseMessage],
human_prefix: str = 'Human',
ai_prefix: str = 'AI',
*,
system_prefix: str = 'System',
function_prefix: str = 'Function',
tool_prefix: str = 'Tool',
message_separator: str = '\n',
format: Literal['prefix', 'xml'] = 'prefix'
) -> strIf a message is an AIMessage and contains both tool calls under tool_calls
and a function call under additional_kwargs["function_call"], only the tool
calls will be appended to the string representation.
When using format='xml':
<message type="role">content</message> format.type attribute uses human_prefix (lowercased) for HumanMessage,
ai_prefix (lowercased) for AIMessage, system_prefix (lowercased)
for SystemMessage, function_prefix (lowercased) for FunctionMessage,
tool_prefix (lowercased) for ToolMessage, and the original role
(unchanged) for ChatMessage.xml.sax.saxutils.escape().xml.sax.saxutils.quoteattr().<content> and
<tool_call> elements.text, reasoning, image (URL/file_id only), image_url
(OpenAI-style, URL only), audio (URL/file_id only), video (URL/file_id
only), text-plain, server_tool_call, and server_tool_result.base64 field or data: URLs).text-plain), server tool call arguments,
and server tool result outputs are truncated to 500 characters.Example:
Default prefix format:
from langchain_core.messages import AIMessage, HumanMessage, get_buffer_string
messages = [
HumanMessage(content="Hi, how are you?"),
AIMessage(content="Good, how are you?"),
]
get_buffer_string(messages)
# -> "Human: Hi, how are you?\nAI: Good, how are you?"XML format (useful when content contains role-like prefixes):
messages = [
HumanMessage(content="Example: Human: some text"),
AIMessage(content="I see the example."),
]
get_buffer_string(messages, format="xml")
# -> '<message type="human">Example: Human: some text</message>\\n'
# -> '<message type="ai">I see the example.</message>'XML format with special characters (automatically escaped):
messages = [
HumanMessage(content="Is 5 < 10 & 10 > 5?"),
]
get_buffer_string(messages, format="xml")
# -> '<message type="human">Is 5 < 10 & 10 > 5?</message>'XML format with tool calls:
messages = [
AIMessage(
content="I'll search for that.",
tool_calls=[
{"id": "call_123", "name": "search", "args": {"query": "weather"}}
],
),
]
get_buffer_string(messages, format="xml")
# -> '<message type="ai">\\n'
# -> ' <content>I\\'ll search for that.</content>\\n'
# -> ' <tool_call id="call_123" name="search">'
# -> '{"query": "weather"}</tool_call>\\n'
# -> '</message>'| Name | Type | Description |
|---|---|---|
messages* | Sequence[BaseMessage] | Messages to be converted to strings. |
human_prefix | str | Default: 'Human'The prefix to prepend to contents of |
ai_prefix | str | Default: 'AI'The prefix to prepend to contents of |
system_prefix | str | Default: 'System'The prefix to prepend to contents of |
function_prefix | str | Default: 'Function'The prefix to prepend to contents of |
tool_prefix | str | Default: 'Tool'The prefix to prepend to contents of |
message_separator | str | Default: '\n'The separator to use between messages. |
format | Literal['prefix', 'xml'] | Default: 'prefix'The output format.
|