How to read Appsettings.Json in .net 6 Web API with F#

Question

我想从 F# 中的 appsettings.json 文件中读取一个简单的连接字符串

  "ConnectionStrings": {
    "myConnectionString": "Server=myServerAddress;Database=myDataBase;User Id=myUsername;Password=myPassword;"
  }

在 C# 中，我可以使用 object 从实现构造函数中提供的 Iconfiguration 的 class 读取连接字符串。 But in the F# web API with .net 6, I couldn't find anything that made me read the connection string section or an other key in from the AppSettings.json file

Here is an example how I could read from the Appsettings.json in C# .net 6 Web API. 这就是我想做的。

public class TestModel : PageModel
{
    // requires using Microsoft.Extensions.Configuration;
    private readonly IConfiguration _configuration;

    public TestModel(IConfiguration configuration)
    {
        _configuration = configuration;
    }

    public void Connect()
    {
      var connectionString = _config.GetConnectionString("myConnectionString");
      // Do Something with the string
    }
}

Answer 1

F# 实现 Web API 项目与 ZD7EFA19FBE7D2372FD5ADB6024 非常相似为了在您的一个类中使用配置，您只需将 IConfiguration 参数注入 class 的构造函数。 默认引导代码负责为配置框架设置依赖注入。

我为 F# 创建了一个示例 Web API 项目，并将 IConfiguration 注入到 Z594C103F2C6E01EABCAZ8

namespace WebApiTest.Controllers

open System
open System.Collections.Generic
open System.Linq
open System.Threading.Tasks
open Microsoft.AspNetCore.Mvc
open Microsoft.Extensions.Logging
open Microsoft.Extensions.Logging
open WebApiTest
open Microsoft.Extensions.Configuration

[<ApiController>]
[<Route("[controller]")>]
type WeatherForecastController (logger : ILogger<WeatherForecastController>, configuration: IConfiguration) =
    inherit ControllerBase()

    let summaries =
        [|
            "Freezing"
            "Bracing"
            "Chilly"
            "Cool"
            "Mild"
            "Warm"
            "Balmy"
            "Hot"
            "Sweltering"
            "Scorching"
        |]

    [<HttpGet>]
    member _.Get() =
        let cstr = configuration.GetConnectionString("MyConnectionString")
        logger.LogInformation($"Connection string: {cstr}")
        let rng = System.Random()
        [|
            for index in 0..4 ->
                { Date = DateTime.Now.AddDays(float index)
                  TemperatureC = rng.Next(-20,55)
                  Summary = summaries.[rng.Next(summaries.Length)] }
        |]

如您所见，在构造函数中注入的configuration参数可以作为 Get() 方法中的私有成员变量进行访问。 我只是记录连接字符串以说明代码按预期工作。 这是我的 appsettings.json：

{
  "ConnectionStrings": {
    "MyConnectionString": "SampleConnectionString"
  },
  "Logging": {
    "LogLevel": {
      "Default": "Information",
      "Microsoft.AspNetCore": "Warning"
    }
  },
  "AllowedHosts": "*"
}