执行GQL

本节介绍如何使用gql()和gqlStream()方法在数据库中执行GQL。

GQL（图查询语言）是ISO标准化的图数据库查询语言。详情参阅GQL文档。

gql()

在数据库中执行GQL语句。

参数

• gql: string：待执行的GQL语句。
• config: RequestConfig（可选）：请求配置。

返回值

• Response：请求结果。

// Retrieves 5 movie nodes from the graph 'miniCircle' and prints their names

const requestConfig: RequestConfig = {
  graph: "miniCircle",
};

let response = await conn.gql(
  "MATCH (n:movie) RETURN n LIMIT 5",
  requestConfig
);
const nodeList = response.items?.get("n")?.asNodes();
nodeList?.forEach((node) => {
  console.log(node.get("name"));
});

The Shawshank Redemption
Farewell My Concubine
Léon: The Professional
Titanic
Life is Beautiful

gqlStream()

在数据库中执行GQL语句并以增量形式返回结果。在处理大型数据集时，避免同时加载所有数据至内存中。

参数

• gql: string：待执行的GQL语句。
• cb: RequestType.QueryResponseListener：流处理监听器。
• config: RequestConfig（可选）：请求配置。

返回值

• void

// Retrieves all 1-step paths from the graph 'miniCircle'

const requestConfig: RequestConfig = {
  graph: "miniCircle",
};

let count = 0;
let response = await conn.gqlStream(
  "MATCH p = ()-[]-() RETURN p",
  // Define the event handler functions
  {
      onStart: () => {
          console.log("Stream started.")
      },
      onData: async (res) => {
          let paths = res.items?.get("p")?.asPaths();
          count = count + (paths?.length || 0);
          console.log(count);
      },
      onEnd: () => {
          console.log("Stream ended.");
      },
      onError: (err) => {
          console.log(err);
      }
  },
  requestConfig
);

Stream started.
1024
2048
3072
3227
3464
3895
Stream ended.

完整示例

import { UltipaDriver } from "@ultipa-graph/ultipa-driver";
import { ULTIPA } from "@ultipa-graph/ultipa-driver/dist/types";

let sdkUsage = async () => {
  // URI example: ultipaConfig.hosts: ["mqj4zouys.us-east-1.cloud.ultipa.com:60010"]
  const ultipaConfig: ULTIPA.UltipaConfig = {
    hosts: ["192.168.1.85:60061", "192.168.1.87:60061", "192.168.1.88:60061"],
    username: "<username>",
    password:  "<password>"
  };

  const conn = new UltipaDriver(ultipaConfig);
  const isSuccess = await conn.test();
  console.log(`Connection succeeds: ${isSuccess}`);

  // Retrieves 5 movie nodes from the graph 'miniCircle' and prints their names

  const requestConfig: ULTIPA.RequestConfig = {
    graph: "miniCircle",
  };
  const response = await conn.gql(
    "MATCH (n:movie) RETURN n LIMIT 5",
    requestConfig
  );
  let nodeList = response.items?.get("n")?.asNodes();
  nodeList?.forEach((node) => {
    console.log(node.get("name"));
  });
};
sdkUsage().catch(console.error);