# Dependency injection

The SurrealDB SDK for .NET also supports the concept of Dependency Injection pattern.

The .NET SDK also support Dependency Injection to ease the use of <code>SurrealDbClient</code> and <code>SurrealDbSession</code> in your application.

## Create a new project

Let's start by creating a new ASP.NET Core web app.

```sh
dotnet new webapp -o SurrealDbWeatherApi
cd SurrealDbWeatherApi
dotnet add package SurrealDb.Net
```

## Define a connection string

Open <code>appsettings.Development.json</code> and replace everything in there with the following code.
We have added a new Connection String called <code>SurrealDB</code> with the default configuration.

```json
{
  "AllowedHosts": "*",
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "ConnectionStrings": {
    "SurrealDB": "Server=http://127.0.0.1:8000;Namespace=test;Database=test;Username=root;Password=secret"
  }
}
```

## Register services

Open <code>Program.cs</code> and replace everything in there with the following code.
This code is using the <code>AddSurreal()</code> extension method to inject services automatically.
Notice that all we have to do is one line of code to configure the SurrealDB client with the previously set Connection String.

> [!NOTE]
> By default, this function will register both <code>ISurrealDbSession</code> and <code>SurrealDbSession</code> using the <code>Scoped</code> service lifetime. This mean that a new isolated SurrealDB session is created per scope.

```csharp
var builder = WebApplication.CreateBuilder(args);

var services = builder.Services;
var configuration = builder.Configuration;

services.AddControllers();
services.AddEndpointsApiExplorer();
services.AddSwaggerGen();
services.AddSurreal(configuration.GetConnectionString("SurrealDB"));

var app = builder.Build();

if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseHttpsRedirection();
app.UseAuthorization();

app.MapControllers();

app.Run();
```

> [!NOTE]
> In this example, we use a [Connection String](/docs/reference/dotnet/core/connection-strings.md) to configure services.
> This is the most convenient way to initialise the <code>SurrealDbClient</code> in your application.
> You can always choose to construct a Connection String manually via a <code>SurrealDbOptionsBuilder</code> and pass it to the <code>AddSurreal()</code> method.

## Consume the SurrealDB client/session

Open <code>WeatherForecastController.cs</code> and replace everything in there with the following code.
Finally, we can inject the <code>SurrealDbSession</code> inside our Controller.

```csharp
using Microsoft.AspNetCore.Mvc;

namespace SurrealDbWeatherApi.Controllers;

[ApiController]
[Route("[controller]")]
public class WeatherForecastController : ControllerBase
{
    private const string Table = "weatherForecast";

    private readonly SurrealDbSession _db;

    public WeatherForecastController(SurrealDbSession db)
    {
        _db = db;
    }

    [HttpGet]
    [Route("/")]
    public Task<List<WeatherForecast>> GetAll(CancellationToken cancellationToken)
    {
        return _db.Select<WeatherForecast>(Table, cancellationToken);
    }

    [HttpPost]
    [Route("/")]
    public Task<WeatherForecast> Create(CreateWeatherForecast data, CancellationToken cancellationToken)
    {
        var weatherForecast = new WeatherForecast
        {
            Date = data.Date,
            Country = data.Country,
            TemperatureC = data.TemperatureC,
            Summary = data.Summary
        };

        return _db.Create(Table, weatherForecast, cancellationToken);
    }

    // ...
    // Other methods omitted for brevity
}

public class CreateWeatherForecast
{
    public DateTime Date { get; set; }
    public string? Country { get; set; }
    public int TemperatureC { get; set; }
    public string? Summary { get; set; }
}
```

Then make sure your SurrealDB server is running on <code>127.0.0.1:8000</code> and run your app from the command line with:

```sh
dotnet run
```