IConfiguration 返回空值。无法从数据库中读取

Question

我有一个 .Net Core 3.1 程序返回错误

System.ArgumentNullException: '值不能为空。 (参数'connectionString')'

当我尝试登录系统时。

我已经设置了断点

public IConfiguration Configuration { get; }

在构建时，可以看到连接字符串，但我立即登录它返回 null。

下面是我的代码。

Startup.cs

public Startup(IConfiguration configuration)
{
    Configuration = configuration;
}

public IConfiguration Configuration { get; }

// This method gets called by the runtime. Use this method to add services to the container.
public void ConfigureServices(IServiceCollection services)
{
    services.AddRazorPages();
    services.AddSession();
    services.AddMvc().AddRazorPagesOptions(options =>
    {
        options.Conventions.AddPageRoute("/Login/Login", "");
    });

    services.AddDbContext<CENTREContext>(options => options.UseSqlServer(Configuration.GetConnectionString("DatabaseConnection")));
    //var connection = Configuration.GetConnectionString("ConnectionStrings");
    //services.Configure<ConnectionStrings>(Configuration.GetSection("DatabaseConnection"));

    //services.AddDbContext<CENTREContext>(options => options.UseSqlServer(connection));
}

上下文类

public CENTREContext(DbContextOptions<CENTREContext> options)
    : base(options)
{
}

public CENTREContext()
{ }

public IConfiguration Configuration { get; }

protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
{
    if (!optionsBuilder.IsConfigured)
    {               
        optionsBuilder.UseSqlServer(Configuration.
        GetConnectionString("ConnectionStrings:DatabaseConnection"));
    }
}

appsettings.json

{
    "ConnectionStrings": {
        "DatabaseConnection": "Server=xx-xx;Database=CENTRE;UID=xx;Password=xxx;"
    },
    "AllowedHosts": "*"
}

我已经尝试过，但似乎没有任何效果。 我们将不胜感激。

Answer 1

你混合了你的选择。

GetSection + 索引运算符

connectionStrings = configuration.GetSection("ConnectionStrings");
connectionString = connectionStrings["DatabaseConnection"];

GetSection + 路径

connectionString = configuration.GetSection("ConnectionStrings:DatabaseConnection").Value;

获取连接字符串

connectionString = configuration.GetConnectionString("DatabaseConnection");

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