完成后端配置，用于部署

nodes/template.py

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+import json
+from urllib.parse import urlparse, urlunparse
+from langchain_community.utilities import SQLDatabase
+from sqlalchemy import Table, MetaData, select, insert, update, delete, and_
+
+# --- 工具函数：URL 标准化 ---
+def normalize_url(url: str) -> str:
+    """
+    标准化 URL，确保末尾斜杠、大小写等不影响唯一性判定
+    """
+    if not url:
+        return url
+    
+    # 1. 解析 URL
+    parsed = urlparse(url.strip())
+    
+    # 2. 转换协议和域名为小写 (Domain 是不区分大小写的)
+    scheme = parsed.scheme.lower()
+    netloc = parsed.netloc.lower()
+    
+    # 3. 处理路径：去除末尾的斜杠
+    path = parsed.path
+    if path.endswith('/'):
+        path = path.rstrip('/')
+    
+    # 4. 去除 Fragment (#部分)，保留 Query 参数
+    # 如果需要忽略 Query 参数，可以将 query 设置为 ""
+    query = parsed.query
+    
+    # 5. 重新拼接
+    normalized = urlunparse((scheme, netloc, path, parsed.params, query, ""))
+    return normalized
+
+# --- 数据库连接工厂 ---
+def get_db_connection(db_url: str):
+    """
+    获取通用数据库连接，处理协议兼容性
+    """
+    if db_url.startswith("postgres://"):
+        db_url = db_url.replace("postgres://", "postgresql+psycopg2://", 1)
+    elif db_url.startswith("postgresql://") and "+psycopg2" not in db_url:
+        db_url = db_url.replace("postgresql://", "postgresql+psycopg2://", 1)
+    
+    try:
+        # engine_args 确保连接池在 Dify 高并发下更稳定
+        return SQLDatabase.from_uri(db_url, engine_args={
+            "pool_pre_ping": True,
+            "pool_recycle": 3600
+        })
+    except Exception as e:
+        raise RuntimeError(f"DB_CONNECT_ERROR: {str(e)}")
+
+# --- Dify 节点主入口 ---
+def main(inputs: dict):
+    """
+    Dify 节点主入口函数
+    """
+    ret = {"code": 0, "msg": "unknown", "data": None}
+    
+    # 预设数据库连接字符串 (建议在 Dify 环境变量中配置)
+    db_url = inputs.get("db_url") 
+
+    try:
+        # 1. 初始化数据库
+        db = get_db_connection(db_url)
+        
+        # 2. 执行具体的业务逻辑
+        result_data = _logic_handler(db, inputs)
+
+        ret["code"] = 1
+        ret["msg"] = "success"
+        ret["data"] = result_data
+
+    except Exception as e:
+        ret["code"] = 0
+        ret["msg"] = str(e)
+        ret["data"] = None
+
+    return ret
+
+# -------------------------------------------------
+# 业务逻辑处理器：每个节点只需修改这里
+# -------------------------------------------------
+def _logic_handler(db: SQLDatabase, inputs: dict):
+    """
+    在这里编写具体的业务操作
+    """
+    engine = db._engine
+    metadata = MetaData()
+    
+    # 示例：获取并标准化 URL
+    raw_url = inputs.get("url", "")
+    clean_url = normalize_url(raw_url)
+    
+    # 反射获取表对象
+    # tasks = Table('crawl_tasks', metadata, autoload_with=engine)
+    
+    # 使用 SQLAlchemy Core 进行操作（无需写原生SQL）
+    # with engine.begin() as conn:
+    #     stmt = select(tasks).where(tasks.c.root_url == clean_url)
+    #     result = conn.execute(stmt).fetchone()
+    
+    return {
+        "processed_url": clean_url,
+        "info": "逻辑已执行"
+    }