retriever = index.as_retriever(verbose=True, chat_mode="context", similarity_top_k=similarity_top_k)
# CustomContext inherits the ContextChatEngine, and just has a small changes for the best results.
custom_chat_engine = CustomContext.from_defaults(
retriever=retriever,
memory=chatmemory,
context_template=generate_context_template(),
system_prompt=prepared_system_prompt,
node_postprocessors=[CustomPostprocessor(
context_limit, query_text + prepared_system_prompt, project.db_name, None)])
response = custom_chat_engine.chat(query_text, chat_history=chat_history)DEFAULT_CONTEXT_TEMPLATE = (
"Context information is below."
"\n--------------------\n"
"{context_str}"
"\n--------------------\n"
)
class CustomContext(ContextChatEngine):
def _get_prefix_messages_with_context(self, context_str: str) -> List[ChatMessage]:
"""Get the prefix messages with context."""
# ensure we grab the user-configured system prompt
system_prompt = ""
prefix_messages = self._prefix_messages
if (
len(self._prefix_messages) != 0
and self._prefix_messages[0].role == MessageRole.SYSTEM
):
system_prompt = str(self._prefix_messages[0].content)
prefix_messages = self._prefix_messages[1:]
context_str_w_sys_prompt = system_prompt.strip() + context_str # Opporsite order <------- the only difference
return [
ChatMessage(content=context_str_w_sys_prompt, role=MessageRole.SYSTEM),
*prefix_messages,
]