如何在服务器端Blazor中访问HttpContext？

Question

我需要访问HttpContext页面（.cshtml），尤其是访问请求和Cookie。尽管可用，但 HttpContextAccessor始终在其属性中存储一个空值HttpContext。

任何想法将不胜感激。

提前致谢。

编辑：我使用的Blazor版本是：0.7.0。

Answer 1

将以下内容添加到Blazor.Web.App.Startup.cs：

services.AddHttpContextAccessor();

您也需要 <component-name>.cshtml

@using Microsoft.AspNetCore.Http
@inject IHttpContextAccessor httpContextAccessor

Answer 2

请注意，文档明确指出 IHttpContextAccessor 不应用于 Blazor 应用程序： https://learn.microsoft.com/en-us/aspnet/core/fundamentals/http-context ?view=aspnetcore-3.1#blazor-and -共享状态

（这并不意味着在您的特定情况下它不适用于特定场景。但无论如何您只能从第一个请求中获取 cookie - 一旦 SignalR 接管就不再有 cookie - 您也许应该得到当 _Host.cshtml 为 renderend 时的值，并将其作为字符串值从那里传递给 Blazor 组件。）

Answer 3

这取决于你想访问什么HttpContext。

如果您想访问身份验证或用户信息，请考虑使用AuthenticationStateProvider：

@page "/"
@using System.Security.Claims
@using Microsoft.AspNetCore.Components.Authorization
@inject AuthenticationStateProvider AuthenticationStateProvider

<h3>ClaimsPrincipal Data</h3>

<button @onclick="GetClaimsPrincipalData">Get ClaimsPrincipal Data</button>

<p>@_authMessage</p>

@if (_claims.Count() > 0)
{
    <ul>
        @foreach (var claim in _claims)
        {
            <li>@claim.Type &ndash; @claim.Value</li>
        }
    </ul>
}

<p>@_surnameMessage</p>

@code {
    private string _authMessage;
    private string _surnameMessage;
    private IEnumerable<Claim> _claims = Enumerable.Empty<Claim>();

    private async Task GetClaimsPrincipalData()
    {
        var authState = await AuthenticationStateProvider.GetAuthenticationStateAsync();
        var user = authState.User;

        if (user.Identity.IsAuthenticated)
        {
            _authMessage = $"{user.Identity.Name} is authenticated.";
            _claims = user.Claims;
            _surnameMessage = 
                $"Surname: {user.FindFirst(c => c.Type == ClaimTypes.Surname)?.Value}";
        }
        else
        {
            _authMessage = "The user is NOT authenticated.";
        }
    }
}

Answer 4

blazor.Sever 到 Startup.cs

public void ConfigureServices(IServiceCollection services)
{
    services.AddServerSideBlazor<Client.Startup>();

    // HttpContextAccessor
    services.AddHttpContextAccessor();
    services.AddScoped<HttpContextAccessor>();
}

blazor.Shared

public class HttpContextAccessor
{
   private readonly IHttpContextAccessor _httpContextAccessor;

   public HttpContextAccessor(IHttpContextAccessor httpContextAccessor)
   {
        _httpContextAccessor = httpContextAccessor;
   }

   public HttpContext Context => _httpContextAccessor.HttpContext;
}

blazor.Client 到 App.cshtml

@inject blazor.Shared.HttpContextAccessor HttpContext
<Router AppAssembly=typeof(Program).Assembly />

@functions 
{      
    protected override void OnInit()
    {
       HttpContext.Context.Request.Cookies.**

       // Or data passed through middleware in blazor.Server
       HttpContext.Context.Features.Get<T>()
    }
}

学分：https : //github.com/aspnet/Blazor/issues/1554