LangChain/app/services/qa_service.py

from app.chains.qa_chain import QAChain
from app.chains.rag_chain import RAGChain
from app.services.vector_store_service import VectorStoreService
from app.core.logger import logger
from app.core.config import settings
from typing import List, Dict, Optional

class QAService:
    """问答服务类，处理问答相关的业务逻辑"""
    
    def __init__(self, model_name: str = None, temperature: float = None):
        """
        初始化问答服务
        
        Args:
            model_name (str, optional): 使用的模型名称，默认使用配置中的值
            temperature (float, optional): 模型温度参数，默认使用配置中的值
        """
        self.qa_chain = QAChain(
            model_name=model_name or settings.DEFAULT_MODEL,
            temperature=temperature or settings.TEMPERATURE
        )
        # 初始化 RAG 相关服务
        self.vector_store_service = VectorStoreService()
        self.rag_chain = RAGChain(self.vector_store_service)
    
    def get_answer(self, question: str, chat_history: Optional[List[Dict[str, str]]] = None, use_rag: bool = True) -> str:
        """
        获取问题的回答
        
        Args:
            question (str): 用户问题
            chat_history (List[Dict[str, str]], optional): 聊天历史记录
            use_rag (bool): 是否使用 RAG 增强回答，默认为 True
            
        Returns:
            str: AI回答
        """
        try:
            logger.info(f"处理问题: {question}")
            
            if use_rag:
                # 使用 RAG 获取回答
                rag_result = self.rag_chain.query(question)
                answer = rag_result["result"]
                # 如果有相关文档，添加到回答中
                if rag_result["source_documents"]:
                    sources = [doc.page_content for doc in rag_result["source_documents"]]
                    answer += "\n\n参考来源：\n" + "\n".join(sources)
            else:
                # 使用基础 QA 获取回答
                answer = self.qa_chain.answer(question, chat_history)
            
            logger.info(f"生成回答完成，长度: {len(answer)}")
            return answer
        except Exception as e:
            logger.error(f"生成回答时发生错误: {str(e)}", exc_info=True)
            raise