The role of MessagesPlaceholder in LangChain.js
The MessagesPlaceHolder in LangChain.js plays a crucial role in enabling dynamic and flexible construction of chat prompts by acting as a placeholder for a list of messages within a ChatPromptTemplate. Its primary functions are Dynamic Message Insertion It allows you to inject a list of BaseMessage objects (like HumanMessage, AIMessage, SystemMessage, etc) into a specific position within your chat prompt template during runtime. This is particularly useful for managing chat history, where the list of past messages needs to be…