community[minor]: add TigerGraph support (#16280)

**Description:** Add support for querying TigerGraph databases through
the InquiryAI service.
**Issue**: N/A
**Dependencies:** N/A
**Twitter handle:** @TigerGraphDB

libs/community/langchain_community/graphs/tigergraph_graph.py

@@ -0,0 +1,94 @@
+from typing import Any, Dict, List, Optional
+
+from langchain_community.graphs.graph_store import GraphStore
+
+
+class TigerGraph(GraphStore):
+    """TigerGraph wrapper for graph operations.
+
+    *Security note*: Make sure that the database connection uses credentials
+        that are narrowly-scoped to only include necessary permissions.
+        Failure to do so may result in data corruption or loss, since the calling
+        code may attempt commands that would result in deletion, mutation
+        of data if appropriately prompted or reading sensitive data if such
+        data is present in the database.
+        The best way to guard against such negative outcomes is to (as appropriate)
+        limit the permissions granted to the credentials used with this tool.
+
+        See https://python.langchain.com/docs/security for more information.
+    """
+
+    def __init__(self, conn: Any) -> None:
+        """Create a new TigerGraph graph wrapper instance."""
+        self.set_connection(conn)
+        self.set_schema()
+
+    @property
+    def conn(self) -> Any:
+        return self._conn
+
+    @property
+    def schema(self) -> Dict[str, Any]:
+        return self._schema
+
+    def get_schema(self) -> str:
+        if self._schema:
+            return str(self._schema)
+        else:
+            self.set_schema()
+            return str(self._schema)
+
+    def set_connection(self, conn: Any) -> None:
+        from pyTigerGraph import TigerGraphConnection
+
+        if not isinstance(conn, TigerGraphConnection):
+            msg = "**conn** parameter must inherit from TigerGraphConnection"
+            raise TypeError(msg)
+
+        if conn.ai.nlqs_host is None:
+            msg = """**conn** parameter does not have nlqs_host parameter defined.
+                     Define hostname of NLQS service."""
+            raise ConnectionError(msg)
+
+        self._conn: TigerGraphConnection = conn
+        self.set_schema()
+
+    def set_schema(self, schema: Optional[Dict[str, Any]] = None) -> None:
+        """
+        Set the schema of the TigerGraph Database.
+        Auto-generates Schema if **schema** is None.
+        """
+        self._schema = self.generate_schema() if schema is None else schema
+
+    def generate_schema(
+        self,
+    ) -> Dict[str, List[Dict[str, Any]]]:
+        """
+        Generates the schema of the TigerGraph Database and returns it
+        User can specify a **sample_ratio** (0 to 1) to determine the
+        ratio of documents/edges used (in relation to the Collection size)
+        to render each Collection Schema.
+        """
+        return self._conn.getSchema(force=True)
+
+    def refresh_schema(self):
+        self.generate_schema()
+
+    def query(self, query: str) -> Dict[str, Any]:
+        """Query the TigerGraph database."""
+        answer = self._conn.ai.query(query)
+        return answer
+
+    def register_query(
+        self,
+        function_header: str,
+        description: str,
+        docstring: str,
+        param_types: dict = {},
+    ) -> List[str]:
+        """
+        Wrapper function to register a custom GSQL query to the TigerGraph NLQS.
+        """
+        return self._conn.ai.registerCustomQuery(
+            function_header, description, docstring, param_types
+        )