本节为您介绍如何在UQL语句中使用Connection对象的uql()方法和uqlStream()方法查询数据库。

每个示例主要展示如何使用所列方法。点击完整示例查看完整代码示例。

UQL (Ultipa Query Language) is the language designed for fully interacting with Ultipa graph databases. For detailed information on UQL, refer to the documentation.

Uql()

在当前图集或数据库上执行GQL查询语句并返回查询结果。

参数：

• string：待执行的UQL查询语句。
• RequestConfig（可选)：配置请求。

返回值：

• Response：请求的结果。

// 获取图集miniCircle中@movie下的5个点并打印其名称

RequestConfig requestConfig = new RequestConfig() { Graph = "miniCircle", UseMaster = true };

var res = await ultipa.Uql("find().nodes({@movie}) as n return n{*} limit 5", requestConfig);
var nodeList = res?.Alias("n")?.AsNodes();
foreach (var node in nodeList)
{
    Console.WriteLine(node.Values.GetValueOrDefault("name"));
}

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

更多示例，请参阅嬴图数据与C#类型映射.

UqlStream()

在当前图集或数据库上执行GQL查询语句并以增量形式返回查询结果。在处理大型数据集时，无需立刻加载所有数据至内存中。

参数：

• string：待执行的UQL查询语句。
• UqlResponseStream：流处理监听器。
• RequestConfig（可选)：配置请求。

返回值：

• void

// 获取图集miniCircle的1步路径
RequestConfig requestConfig = new RequestConfig() { Graph = "miniCircle", UseMaster = true };

var count = 0;
await ultipa.UqlStream(
    "n().e().n() as paths return paths{*}",
    new UqlResponseStream()
    {
        OnStart = () => Console.WriteLine("Start"),
        OnData = (
            resp =>
            {
                if (resp.Status.ErrorCode != ErrorCode.Success)
                {
                    Console.WriteLine(resp.Status.Msg);
                }
                var paths = resp.Get(0).AsPaths();
                count += paths.Count();

                Console.WriteLine($"Count ={count}");
                return true;
            }
        ),

        OnEnd = () => Console.WriteLine("End"),
    },
    requestConfig
);

Start
Count =  1390
End

完整示例

using System.Security.Cryptography.X509Certificates;
using Microsoft.Extensions.Logging;
using Newtonsoft.Json;
using UltipaService;
using UltipaSharp;
using UltipaSharp.api;
using UltipaSharp.configuration;
using UltipaSharp.connection;
using UltipaSharp.exceptions;
using UltipaSharp.structs;
using UltipaSharp.utils;
using Logger = UltipaSharp.utils.Logger;
using Property = UltipaSharp.structs.Property;
using Schema = UltipaSharp.structs.Schema;

class Program
{
    static async Task Main(string[] args)
    {
        // 设置连接
        //URI示例： Hosts=new[]{"mqj4zouys.us-east-1.cloud.ultipa.com:60010"}
        var myconfig = new UltipaConfig()
        {
            Hosts = new[] { "192.168.1.85:60061", "192.168.1.86:60061", "192.168.1.87:60061" },
            Username = "***",
            Password = "***",
        };

        // 建立与数据库的连接
        var ultipa = new Ultipa(myconfig);
        var isSuccess = ultipa.Test();
        Console.WriteLine(isSuccess);


        // 配置请求
        RequestConfig requestConfig = new RequestConfig() { Graph = "miniCircle", UseMaster = true };

        // 获取10个点并打印返回的第一个点的_id和storeName属性值
        var res = await ultipa.Uql(
            "find().nodes({@movie}) as n return n{*} limit 10",
            requestConfig
        );

        var nodeList = res?.Get(0).AsNodes();
        if (nodeList[0].Values.TryGetValue("name", out object? value))
        {
            Console.WriteLine(value);
        }
        Console.WriteLine(nodeList[0].Id);
    }
}