如何在asp.net core中的startup.cs文件的configure方法中更改作用域服务的属性值

Question

如何在asp.net core中的startup.cs文件的configure方法中更改作用域服务的属性值

我将在startup.cs 文件中更改或插入一些值到我的作用域服务中。

这是我的代码。

我正在向 MyService.SomeData 属性插入一个值。但是，在视图页面中，打印空值。

这是为什么？

启动.cs

namespace MyProject
{
    public class Startup
    {
        .
        .
        .
        public void ConfigureServices(IServiceCollection services)
        {
            .
            .
            .
            services.AddSingleton<IHttpContextAccessor, HttpContextAccessor>();
            services.AddScoped<MyService>();
        }

        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            var scope = app.ApplicationServices.CreateScope();
            var MyService = scope.ServiceProvider.GetService<MyService>();
            app.Use(async (context, next) => 
            {
                if (context.Request.Query.ContainKey("conditionKey") && context.Request.Query["conditonKey"] == "something")
                {
                    MyService.SomeData = "foo";
                }
            });
        }
    }
}

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MyService.cs

namespace MyProject.Service
{
    public class MyService
    {
        public string SomeData { get; set; } = "";
    {
}

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MyView.cshtml

@inject MyProject.Service.MyService MyService
<!DOCTYPE html>
<html lang="en">
<head>
</head>
<body>
    <div>@MyService.SomeData</div>
</body>

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Answer 1

pwr*_*imo 6

ASP.NET Core 管道为每个 http 请求创建作用域，因此您需要在操作方法内设置此属性

public class HomeController : Controller
{
    private readonly MyService myService;

    public HomeController(MyService myService)
    {
        this.myService = myService;
    }

    public IActionResult Index()
    {
        myService.MyData = "MyData";

        return View();
    }
}

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或者将您的服务注册为单例

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


public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    var scope = app.ApplicationServices.CreateScope();
    var MyService = scope.ServiceProvider.GetService<MyService>();

    MyService.MyData = "SomeData";
}

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或者注册自定义过滤器并将其集成到管道中

public void ConfigureServices(IServiceCollection services)
{
    services.AddControllersWithViews(x => x.Filters.Add(typeof(MyServiceFilter)));

    services.AddScoped<MyService>();
}


public class MyServiceFilter : IActionFilter
{
    private readonly MyService myService;

    public MyServiceFilter(MyService myService)
    {
        this.myService = myService;
    }

    public void OnActionExecuted(ActionExecutedContext context)
    {
    }

    public void OnActionExecuting(ActionExecutingContext context)
    {
        myService.MyData = "MyData";
    }
}

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最后，使用app.Use

app.Use(async (context, next) =>
{
    if (context.Request.Query.ContainsKey("conditionKey") && context.Request.Query["conditionKey"] == "something")
    {
        var myService = context.RequestServices.GetService<MyService>();

        myService.MyData = "foo";
    }

    await next();
});

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