尝试将数据库上下文注入自定义中间件时出现 InvalidOperationException答案

【问题标题】：Getting InvalidOperationException when trying to inject db context into custom middleware尝试将数据库上下文注入自定义中间件时出现 InvalidOperationException
【发布时间】：2018-01-30 21:57:45
【问题描述】：

我需要将一个 db 上下文对象注入一个名为 AuthenticateClient 的自定义中间件，但我得到了异常：

InvalidOperationException：无法解析范围服务来自根提供商的“LC.Tools.API.Data.ApiDbContext”。

AuthenticateClient.cs：

public class AuthenticateClient
{
    private readonly RequestDelegate _next;
    private readonly ILogger _logger;
    private readonly GenericUnitOfWork _worker;

    public AuthenticateClient(RequestDelegate next, ApiDbContext db, IHttpContextAccessor httpContext, IHostingEnvironment env, ILoggerFactory loggerFactory, IOptions<Utility.LCLog.Settings> settings)
    {
        _next = next;
        _logger = loggerFactory.CreateLogger(settings.Value.ApplicationName);
        _worker = new GenericUnitOfWork(new AppHelper(httpContext, db, env));
    }

    public async Task Invoke(HttpContext context)
    {
        if (!context.Request.Headers.Keys.Contains("key") || !context.Request.Headers.Keys.Contains("pass"))
        {
            context.Response.StatusCode = 400;
            await context.Response.WriteAsync("Key or Pass missing from request header values");

            return;
        }
        else
        {
            Client client;
            string key, pass;

            key = context.Request.Headers["key"];
            pass = context.Request.Headers["pass"];

            client = await _worker.GetRepo<Client>().SingleOrDefault(clnt => clnt.Active && clnt.Key.Equals(key) && clnt.Password.Equals(pass));

            if (client == null)
            {
                _logger.LogWarning("Client authentication failed", new string[] { "Key: " + key, "Password: " + pass, "Host: " + context.Request.Host });

                context.Response.StatusCode = 401;
                await context.Response.WriteAsync("Authentication failed");

                return;
            }
        }

        await _next.Invoke(context);
    }
}

AuthenticateClientExtension.cs：

public static class AuthenticateClientExtension
{
    public static IApplicationBuilder UseClientAuthentication(this IApplicationBuilder builder)
    {
        return builder.UseMiddleware<AuthenticateClient>();
    }
}

Startup.cs：

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<ApiDbContext>(options => options.UseSqlServer(this.ConnectionString));

    services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();

    services.AddMvc();
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IOptions<Settings> lclog)
{
    loggerFactory.AddLCLog(lclog.Value);

    app.UseClientAuthentication();
    app.UseMvc();
}

ApiDbContext.cs：

public class ApiDbContext : DbContext, IApiDbContext
{
    public ApiDbContext(DbContextOptions<ApiDbContext> options) : base(options) { }

    protected override void OnModelCreating(ModelBuilder builder)
    {
        ...
    }
}

【问题讨论】：

ApiDbContext 类是什么样的？有依赖吗？
问题使用 ApiDbContext 类更新
什么是AddEntityFrameworkSqlServer？没有它，你的应用还能运行吗？
我不知道如何以任何其他方式设置数据库上下文
我已经更改了注册 ApiDbContext 的方式，但仍然出现同样的错误

标签： c# asp.net-core asp.net-core-mvc

【解决方案1】：

解决方案是使用 IApplicationBuilder 创建范围和初始化 ApiDbContext 并将其传递给中间件对象。我还更改了注册 ApiDbContext
的方式

AuthenticateClientExtension.cs：

public static class AuthenticateClientExtension
{
    public static IApplicationBuilder UseClientAuthentication(this IApplicationBuilder builder)
    {
        var scope = builder.ApplicationServices.CreateScope();
        ApiDbContext db = scope.ServiceProvider.GetRequiredService<ApiDbContext>();

        return builder.UseMiddleware<AuthenticateClient>(db);
    }
}

Startup.cs：

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<ApiDbContext>(options => options.UseSqlServer(this.ConnectionString));

    ...
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory, IOptions<Settings> lclog)
{
    ...

    app.UseClientAuthentication();
    app.UseMvc();
}

【讨论】：