In the Cypher Fundamentals course, we cover how to query Neo4j using a language called Cypher. To execute a Cypher statement against a Neo4j database you will use an object called a Driver.
The Driver object is a thread-safe, application-wide fixture from which all Neo4j interaction derives.
The Driver API is topology independent, so you can run the same code against a Neo4j cluster or a single DBMS.
To connect to and query Neo4j from within a .NET application, you use the Neo4j .NET Driver.
The Neo4j .NET Driver is one of five officially supported drivers, the others are Java, JavaScript, Python, and Go. There are also a wide range of Community Drivers available for other languages including PHP and Ruby.
You should create a single instance of the Driver in your application per Neo4j cluster or DBMS, which can then be shared across your application.
Installing the Driver
The Neo4j .NET Driver is distributed via the NuGet Gallery. You can find the latest version of the driver by visiting https://www.nuget.org/packages/Neo4j.Driver/.
To install the latest version of the driver using NuGet in Visual Studio, you can run the following command
PM> Install-Package Neo4j.DriverAlternatively, you can run the dotnet add command to add the dependency.
dotnet add Neoflix package Neo4j.DriverThis will add a new entry to the .csproj file for your project
<PackageReference Include="Neo4j.Driver" Version="5.1.0" />Creating a Driver Instance
Each driver instance will connect to one DBMS, or Neo4j cluster, depending on the value provided in the connection string.
You will then use the using keyword to include the Neo4j.Driver namespace into your C# classes.
The static GraphDatabase class provides a Driver method for creating a new driver implementation.
The Driver() method requires two arguments:
-
A connection string for the Neo4j cluster or DBMS - for example
neo4j://localhost:7687orneo4j+s://dbhash.databases.neo4j.io:7687 -
An authentication token - Neo4j supports basic username and password authentication, kerberos tokens or custom authentication. You can create an authentication token by calling one of the static methods provided by
AuthTokens.
Here is an example for how to create a driver instance:
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Unresolved directive in lesson.adoc - include::https://raw.githubusercontent.com/neo4j-graphacademy/llm-vectors-unstructured/main/Examples/Neo4jExamples/Program.cs[tag=driver,indent=0]The above example creates an unencrypted connection to the Neo4j server at localhost on the default port number of 7687.
The driver then attemps to authenticate against the server using a basic authentication with the username neo4j and password letmein!.
Verifying Connectivity
You can verify that the connection details used during driver instantiation are correct by calling the verifyConnectivity() function.
This function returns the Driver instance if the connection details are correct, or fails with a Neo.ClientError.Security.Unauthorized Exception if a connection could not be made.
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Console.WriteLine("Connection Verified!");Check Your Understanding
1. Which of the following programming languages have officially supported drivers?
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✓ .NET
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✓ Go
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✓ Java
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✓ JavaScript
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✓ Python
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❏ PHP
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❏ Ruby
Hint
Five languages are officially supported by Neo4j.
Solution
The five supported languages are .NET, Go, Java, JavaScript and Python.
2. What name is the Neo4j .NET Driver distributed via the NuGet Gallery?
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❏
GraphDatabases.Neo4j -
❏
Neo4j -
✓
Neo4j.Driver -
❏
Neo4j.GraphDatabase
Hint
The package is registered under Neo4j.Driver.
Solution
The package is registered under Neo4j.Driver.
Lesson Summary
In this lesson, you learned about the Neo4j .NET Driver and how it can be used to connect to Neo4j from within a Java application.
In the next lesson, we will take a closer look at the first argument in the GraphDatabase.Driver() method, the connection string.