C# quick start

At the end of this guide, you will have created a simple . NET console Hello, World! program that connects to the Memgraph database and executes simple queries.

Prerequisites

For this guide you will need:

• A running Memgraph instance. If you need to set up Memgraph, take a look at the Installation guide.
  caution

  In order for the Neo4j driver to work, you need modify configuration setting --bolt-server-name-for-init. When running Memgraph, set --bolt-server-name-for-init=Neo4j/5.2.0. If you use other version of Neo4j driver, make sure to put the appropriate version number.

• A basic understanding of graph databases and the property graph model.

Driver

Please note that the code samples in this guide utilize the Neo4j.Driver.Simple package which implements a blocking interface around the 'main' driver. It should be used as a tool for getting started quickly. The Neo4j.Driver package contains the official and complete driver for real-world projects. The driver documentation can be found here: Neo4j . NET Driver.

Basic Setup

We'll be using Visual Studio 2022 on Windows 10 to connect a simple . NET console application to a running Memgraph instance. If you're using a different IDE, the steps might be slightly different, but the code is either the same or very similar.

Let's jump in and connect a simple program to Memgraph.

1. Open Visual Studio and create a new project.
2. Find and select the Console App (. NET Core) template by using the search box.
3. Name your project MemgraphApp, choose an appropriate location for it, and click Create.
4. Select the Tools > Manage NuGet Packages menu command.
5. Once the window opens, search for the Neo4j.Driver.Simple.
6. Select the appropriate driver and click Add package.

Now, you should have the newest version of the driver installed and can proceed to copy the following code into the Program.cs file.

using Neo4j.Driver;

namespace MemgraphApp
{
    public class Program
    {
        public static void Main()
        {
            string message = "Hello, World!";

            using var _driver = GraphDatabase.Driver("bolt://localhost:7687", AuthTokens.None);
            using var session = _driver.Session();

            var greeting = session.ExecuteWrite(tx =>
            {
                var result = tx.Run("CREATE (n:FirstNode) " +
                                    "SET n.message = $message " +
                                    "RETURN 'Node '  + id(n) + ': ' + n.message",
                    new { message });
                return result.Single()[0].As<string>();
            });
            Console.WriteLine(greeting);
        }
    }
}

Once you run the program, you should see an output similar to the following:

Node 1: Hello, World!

caution

To configure indexes and constraints properly, do one operation at a time and use the non-transactional API:

await session.RunAsync(query: "CREATE INDEX ON :FirstNode");
await session.RunAsync(query: "CREATE INDEX ON :FirstNode(message)");

Alternative Setup

If you want to try out more complex operations, feel free to use the refactored code below.

using Neo4j.Driver;

namespace MemgraphApp
{
    public class Program : IDisposable
    {
        private readonly IDriver _driver;

        public Program(string uri, string user, string password)
        {
            _driver = GraphDatabase.Driver(uri, AuthTokens.Basic(user, password));
        }

        public void PrintGreeting(string message)
        {
            using (var session = _driver.Session())
            {
                var greeting = session.ExecuteWrite(tx =>
                {
                    var result = tx.Run("CREATE (n:FirstNode) " +
                                        "SET n.message = $message " +
                                        "RETURN 'Node '  + id(n) + ': ' + n.message",
                        new { message });
                    return result.Single()[0].As<string>();
                });
                Console.WriteLine(greeting);
            }
        }

        public void Dispose()
        {
            _driver?.Dispose();
        }

        public static void Main()
        {
            using (var greeter = new Program("bolt://localhost:7687", "", ""))
            {
                greeter.PrintGreeting("Hello, World!");
            }
        }
    }
}

Where to next?

For real-world examples of how to use Memgraph, we suggest you take a look at the Tutorials page. You can also browse through the How-to guides section to get an overview of all the functionalities Memgraph offers.