DotNETCore 学习笔记 配置

Configuration

var builder = new ConfigurationBuilder();
builder.AddInMemoryCollection();
var config = builder.Build();
config["somekey"] = "somevalue";

// do some other work

var setting = config["somekey"]; // also returns "somevalue"

{
  "ConnectionStrings": {
    "DefaultConnection": "Server=(localdb)\\mssqllocaldb;Database=aspnet-WebApplication1-26e8893e-d7c0-4fc6-8aab-29b59971d622;Trusted_Connection=True;MultipleActiveResultSets=true"
  },
  "Logging": {
    "IncludeScopes": false,
    "LogLevel": {
      "Default": "Debug",
      "System": "Information",
      "Microsoft": "Information"
    }
  }
}

// work with with a builder using multiple calls
var builder = new ConfigurationBuilder();
builder.SetBasePath(Directory.GetCurrentDirectory());
builder.AddJsonFile("appsettings.json");
var connectionStringConfig = builder.Build();

// chain calls together as a fluent API
var config = new ConfigurationBuilder()
    .SetBasePath(Directory.GetCurrentDirectory())
    .AddJsonFile("appsettings.json")
    .AddEntityFrameworkConfig(options =>
        options.UseSqlServer(connectionStringConfig.GetConnectionString("DefaultConnection"))
    )
    .Build();

public Startup(IHostingEnvironment env)
{
    var builder = new ConfigurationBuilder()
        .SetBasePath(env.ContentRootPath)
        .AddJsonFile("appsettings.json", optional: true, reloadOnChange: true)
        .AddJsonFile($"appsettings.{env.EnvironmentName}.json", optional: true);

    if (env.IsDevelopment())
    {
        // For more details on using the user secret store see http://go.microsoft.com/fwlink/?LinkID=532709
        builder.AddUserSecrets();
    }

    builder.AddEnvironmentVariables();
    Configuration = builder.Build();
}

 public static void Main(string[] args)
        {
            var builder = new ConfigurationBuilder();
            Console.WriteLine("Initial Config Sources: " + builder.Sources.Count());

            builder.AddInMemoryCollection(new Dictionary<string, string>
            {
                { "username", "Guest" }
            });

            Console.WriteLine("Added Memory Source. Sources: " + builder.Sources.Count());

            builder.AddCommandLine(args);
            Console.WriteLine("Added Command Line Source. Sources: " + builder.Sources.Count());

            var config = builder.Build();
            string username = config["username"];

            Console.WriteLine($"Hello, {username}!");
        }
-----------------------------------------------------------------------------------------
Using Options and configuration objects
public class MyOptions
{
    public string Option1 { get; set; }
    public int Option2 { get; set; }
}

public class HomeController : Controller
{
    private readonly IOptions<MyOptions> _optionsAccessor;

    public HomeController(IOptions<MyOptions> optionsAccessor)
    {
        _optionsAccessor = optionsAccessor;
    }

    // GET: /<controller>/
    public IActionResult Index() => View(_optionsAccessor.Value);
}

public void ConfigureServices(IServiceCollection services)
{
    // Setup options with DI
    services.AddOptions();

    // Configure MyOptions using config by installing Microsoft.Extensions.Options.ConfigurationExtensions
    services.Configure<MyOptions>(Configuration);

    // Configure MyOptions using code
    services.Configure<MyOptions>(myOptions =>
    {
        myOptions.Option1 = "value1_from_action";
    });

    // Configure MySubOptions using a sub-section of the appsettings.json file
    services.Configure<MySubOptions>(Configuration.GetSection("subsection"));

    // Add framework services.
    services.AddMvc();
}

---------------------------------------------------------------------------------------

Writing custom providers

public class ConfigurationValue
{
    public string Id { get; set; }
    public string Value { get; set; }
}
public class ConfigurationContext : DbContext
{
    public ConfigurationContext(DbContextOptions options) : base(options)
    {
    }

    public DbSet<ConfigurationValue> Values { get; set; }
}

public class EntityFrameworkConfigurationSource : IConfigurationSource
    {
        private readonly Action<DbContextOptionsBuilder> _optionsAction;

        public EntityFrameworkConfigurationSource(Action<DbContextOptionsBuilder> optionsAction)
        {
            _optionsAction = optionsAction;
        }

        public IConfigurationProvider Build(IConfigurationBuilder builder)
        {
            return new EntityFrameworkConfigurationProvider(_optionsAction);
        }
    }

    public class EntityFrameworkConfigurationProvider : ConfigurationProvider
    {
        public EntityFrameworkConfigurationProvider(Action<DbContextOptionsBuilder> optionsAction)
        {
            OptionsAction = optionsAction;
        }

        Action<DbContextOptionsBuilder> OptionsAction { get; }

        public override void Load()
        {
            var builder = new DbContextOptionsBuilder<ConfigurationContext>();
            OptionsAction(builder);

            using (var dbContext = new ConfigurationContext(builder.Options))
            {
                dbContext.Database.EnsureCreated();
                Data = !dbContext.Values.Any()
                    ? CreateAndSaveDefaultValues(dbContext)
                    : dbContext.Values.ToDictionary(c => c.Id, c => c.Value);
            }
        }

        private static IDictionary<string, string> CreateAndSaveDefaultValues(
            ConfigurationContext dbContext)
        {
            var configValues = new Dictionary<string, string>
                {
                    { "key1", "value_from_ef_1" },
                    { "key2", "value_from_ef_2" }
                };
            dbContext.Values.AddRange(configValues
                .Select(kvp => new ConfigurationValue { Id = kvp.Key, Value = kvp.Value })
                .ToArray());
            dbContext.SaveChanges();
            return configValues;
        }
    }
 public static class EntityFrameworkExtensions
    {
        public static IConfigurationBuilder AddEntityFrameworkConfig(
            this IConfigurationBuilder builder, Action<DbContextOptionsBuilder> setup)
        {
            return builder.Add(new EntityFrameworkConfigurationSource(setup));
        }
    }

using System;
using System.IO;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Configuration;

namespace CustomConfigurationProvider
{
    public static class Program
    {
        public static void Main()
        {
            // work with with a builder using multiple calls
            var builder = new ConfigurationBuilder();
            builder.SetBasePath(Directory.GetCurrentDirectory());
            builder.AddJsonFile("appsettings.json");
            var connectionStringConfig = builder.Build();

            // chain calls together as a fluent API
            var config = new ConfigurationBuilder()
                .SetBasePath(Directory.GetCurrentDirectory())
                .AddJsonFile("appsettings.json")
                .AddEntityFrameworkConfig(options =>
                    options.UseSqlServer(connectionStringConfig.GetConnectionString("DefaultConnection"))
                )
                .Build();

            Console.WriteLine("key1={0}", config["key1"]);
            Console.WriteLine("key2={0}", config["key2"]);
            Console.WriteLine("key3={0}", config["key3"]);
        }
    }
}