如何从appsettings.json中读取

Question

我有appsettings.json

{
  "Logging": {
    "IncludeScopes": false,
    "LogLevel": {
      "Default": "Warning"
    }
  },

  "ConnectionString": "Server=...;Database=...;Trusted_Connection=True;"

}

和数据库类

public class Database : DbContext
    {
        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
            => optionsBuilder.UseSqlServer(@"Server=...;Database=...;Trusted_Connection=True;");

        protected override void OnModelCreating(ModelBuilder modelBuilder)
        {
            modelBuilder.Entity<Material>().ToTable("vw_Material", schema: "query");
        }

        public virtual DbSet<Material> Material { get; set; }
    }

我的问题是,如何更换这条线

optionsBuilder.UseSqlServer(@"Server=...;Database=...;Trusted_Connection=True;");

从appsettings的价值？

Answer 1

您可以将DI用于此目的.为此,您需要在Startup.cs中注册Configuration:

public void ConfigureServices(IServiceCollection services)
{
   ...    
   services.AddSingleton<IConfiguration>(Configuration);
}

然后你可以将它注入到数据库构造函数中:

private readonly IConfiguration configuration;

public Database(IConfiguration config) 
{
    configuration = config;
}

并在配置时访问它:

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        => optionsBuilder.UseSqlServer(configuration.GetConnectionString("ConnectionString"));

另一种选择是使用选项模式.在这种情况下,您必须使用所需的属性创建一个类:

public class ConnectionStringConfig
{
    public string ConnectionString { get; set; }
}

在Startup上注册:

public void ConfigureServices(IServiceCollection services)
{
   ...    
   services.Configure<ConnectionStringConfig>(Configuration);
}

注入数据库构造函数:

private readonly ConnectionStringConfig configuration;

public Database(IOptions<ConnectionStringConfig> config) 
{
    configuration = config.Value;
}

并在配置时访问它:

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        => optionsBuilder.UseSqlServer(configuration.ConnectionString);