Question

我已经在我的第一个ASP.NET（Core 2.1）应用程序中添加了一些自定义设置，但我不知道如何从C＃访问它。我想我没有正确地初始化它，有人可以看一下吗？

appsettings.js：

"DatabaseSettings": 
{
    "Hostname": "localhost",
    "Port": "12345",
    "DbName": "myDatabase"
}

以下是它的课程：

public class DatabaseSettings
{
    public string Hostname { get; set; }
    public int Port { get; set; }
    public string DbName { get; set; }
}

Startup.cs：

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddMvc();
        services.Configure<DatabaseSettings>(Configuration.GetSection("DatabaseSettings"));
    }

    public void Configure(IApplicationBuilder app, IHostingEnvironment env)
    {
        if (env.IsDevelopment())
            app.UseDeveloperExceptionPage();
        app.UseMvc();
        var databaseSettings = Configuration.Get<DatabaseSettings>();
        Mongo.Initialize("mongodb://" + databaseSettings.Hostname + ":" + databaseSettings.Port, databaseSettings.DbName);
    }
}

属性返回null。

Answer 1

只需将您的Configuration变量设为全局。你可以把它放在任何地方启动

public class Startup
{
    public IConfiguration Configuration { get; set; }

    public Startup(IConfiguration configuration)
    {
        Configuration = configuration;
    }
   public void ConfigureServices(IServiceCollection services)
   {
    services.AddMvc();
    services.Configure<DatabaseSettings>(Configuration.GetSection("DatabaseSettings"));
   }

  public void Configure(IApplicationBuilder app, IHostingEnvironment env)
  {
    if (env.IsDevelopment())
        app.UseDeveloperExceptionPage();
    app.UseMvc();
    var settingsSection = Configuration.GetSection("DatabaseSettings");
    var settings = settingsSection.Get<DatabaseSettings>();
    Mongo.Initialize("mongodb://" + settings.Hostname + ":" + settings.Port, settings.DbName);
  }
}

Answer 2

使用services.Configure<T>()添加设置后，可以使用IOptions<T>将其注入其他类。您还可以通过在启动类的IOptions<T>方法中指定Configure()来引用它。在你的情况下：

public void Configure(IApplicationBuilder app, IHostingEnvironment env, IOptions<DatabaseSettings> settings)
{
    if (env.IsDevelopment())
        app.UseDeveloperExceptionPage();
    app.UseMvc();
    var databaseSettings = settings.Value;
    Mongo.Initialize("mongodb://" + databaseSettings.Hostname + ":" + databaseSettings.Port, databaseSettings.DbName);
}

Answer 3

添加到Nicholas Reynolds answer 你可以用

var sett = new DatabaseSettings();
Configuration.GetSection("DatabaseSettings").Bind(sett);

或者如果你想获得单一价值，你可以使用

var hostname = Configuration.GetSection("DatabaseSettings:Hostname");

如何从appsettings.js加载自定义设置

3 个答案: