读取 .Net 5 中间件中的请求正文

Question

我正在尝试读取从客户端发送到我的后端的请求正文。内容以 JSON 格式发送，并由用户从表单输入。如何在为控制器路由设置的中间件中读取请求正文。

这是我的模型

namespace ChatboxApi.Models
{
    public class User
    {
        public string Login { get; set; } = default;
        public string Password { get; set; } = default;
        public string Email { get; set; } = default;
        public string FullName { get; set; } = default;
        public int Phone { get; set; } = default;
        public string Website { get; set; } = default;

    }
}

这是我的控制器

namespace ChatboxApi.Controllers
{
    [ApiController]
    [Route("api/signup")]
    public class SignupController : ControllerBase
    {
        [HttpPost]
        public ActionResult SignUp([FromBody] User user)
        {
            return Ok(user);
        }

    }
}

这是我的中间件类

namespace ChatboxApi.Middleware
{
    public class CreateSession
    {
        private readonly RequestDelegate _next;

        public CreateSession(RequestDelegate next)
        {
            this._next = next;
        }

        public async Task Invoke(HttpContext httpContext)
        {
           //I want to get the request body here and if possible
           //map it to my user model and use the user model here.
            
            
        }

}

Answer 1

通常Request.Body不支持倒带，因此只能读取一次。一个临时解决方法是在调用后立即拉出主体EnableBuffering，然后将流倒回至 0 并且不处置它：

public class CreateSession
{
    private readonly RequestDelegate _next;

    public CreateSession(RequestDelegate next)
    {
        this._next = next;
    }

    public async Task Invoke(HttpContext httpContext)
    {
        var request = httpContext.Request;
        if (request.Method == HttpMethods.Post && request.ContentLength > 0)
        {
            request.EnableBuffering();
            var buffer = new byte[Convert.ToInt32(request.ContentLength)];
            await request.Body.ReadAsync(buffer, 0, buffer.Length);
            //get body string here...
            var requestContent = Encoding.UTF8.GetString(buffer);

            request.Body.Position = 0;  //rewinding the stream to 0
        }
        await _next(httpContext);

    }
}

注册服务：

public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
{
    //...
    app.UseHttpsRedirection();

    app.UseMiddleware<CreateSession>();

    app.UseRouting();

    app.UseAuthorization();

    app.UseEndpoints(endpoints =>
    {
        endpoints.MapControllers();
    });

}