Source code for langchain_community.graphs.memgraph_graph

from langchain_community.graphs.neo4j_graph import Neo4jGraph

SCHEMA_QUERY = """
CALL llm_util.schema("raw")
YIELD *
RETURN *
"""


class MemgraphGraph(Neo4jGraph):
    """Memgraph图操作的包装器。

    *安全提示*: 确保数据库连接使用的凭据范围狭窄，仅包括必要的权限。
        如果未这样做，可能会导致数据损坏或丢失，因为调用代码可能尝试执行会导致删除、变异数据（如果适当提示）或读取敏感数据（如果数据库中存在此类数据）的命令。
        防范这些负面结果的最佳方法是（根据需要）限制授予此工具使用的凭据的权限。

        有关更多信息，请参见 https://python.langchain.com/docs/security。"""

    def __init__(
        self, url: str, username: str, password: str, *, database: str = "memgraph"
    ) -> None:
        """创建一个新的Memgraph图包装实例。"""
        super().__init__(url, username, password, database=database)

    def refresh_schema(self) -> None:
        """
        刷新Memgraph图模式信息。
        """

        db_structured_schema = self.query(SCHEMA_QUERY)[0].get("schema")
        assert db_structured_schema is not None
        self.structured_schema = db_structured_schema

        # Format node properties
        formatted_node_props = []

        for node_name, properties in db_structured_schema["node_props"].items():
            formatted_node_props.append(
                f"Node name: '{node_name}', Node properties: {properties}"
            )

        # Format relationship properties
        formatted_rel_props = []
        for rel_name, properties in db_structured_schema["rel_props"].items():
            formatted_rel_props.append(
                f"Relationship name: '{rel_name}', "
                f"Relationship properties: {properties}"
            )

        # Format relationships
        formatted_rels = [
            f"(:{rel['start']})-[:{rel['type']}]->(:{rel['end']})"
            for rel in db_structured_schema["relationships"]
        ]

        self.schema = "\n".join(
            [
                "Node properties are the following:",
                *formatted_node_props,
                "Relationship properties are the following:",
                *formatted_rel_props,
                "The relationships are the following:",
                *formatted_rels,
            ]
        )