Converting HumanMessage and AIMessage to Strings in LangChain

LangChain usually represents messages as it's own message types like HumanMessage, AIMessage, SystemMessage, etc

Sometime, you might want to convert it into plan string which you can do it using get_buffer_string

Here is how to do it

Python

from langchain_core import AIMessage, HumanMessage
from langchain_core.messages.utils import get_buffer_string

messages = [
    HumanMessage(content="Hi, how are you?"),
    AIMessage(content="Good, how are you?"),
]
messages_string = get_buffer_string(messages)
# Output: "Human: Hi, how are you?\n\nAI: Good, how are you?"

Javascript / Typescript

import { AIMessage, HumanMessage } from '@langchain/core/messages';
import { getBufferString } from '@langchain/core/messages';
const messages = [
    new HumanMessage(message.content),
    new AIMessage(message.content)
];

const messagesAsString = getBufferString(messages)

Happy converting strings!