.net core reads Response.Body

.net core reads Response.Body

 public static async Task GetBodyForm(this HttpContext http)
         {
             var content = string.Empty;
             var request = http.Request;

             try
             {
                 request.Body.Position = 0;

                 using var reader = new StreamReader(request.Body, Encoding.UTF8, leaveOpen: true);
                 var strRequestBody = await reader.ReadToEndAsync();
                 Console.WriteLine("ok");
                 Console.WriteLine(strRequestBody == null ? "null" : strRequestBody);
                 request.Body.Position = 0;
             }
             catch (Exception ex)
             {
                 Console.WriteLine("err");
                 Console.WriteLine(ex);
             }
             return content;
         }
 

Read Request.Body in ActionFilter

 public class ActionFilterTestA : ActionFilterAttribute
     {
         public override async void OnActionExecuting(ActionExecutingContext context)
         {
             Console.WriteLine("From Request Body---->");
             Console.WriteLine(await context.HttpContext.GetBodyForm());
             Console.WriteLine("From Request Body---->");
         }
     }
 

An error is reported, usually NotSupportedException is reported at Request.Body

Solution

Call EnableBuffering()

in custom middleware

 app.Use(async (context, next) =>
     {
         context.Request.EnableBuffering();
         await next();
     });
 

Question

(Remove the correct solution code above) Why does calling context.HttpContext.Request.EnableBuffering(); in ActionFilterTestA have no effect? (No error is reported, but the content is an empty string)

Guess

The request body flow is consumed before the ActionFilter and after the custom middleware. Middleware execution sequence

Test

 // Cancel model binding
     builder.Services.Configure(options =>
     {
         options.SuppressInferBindingSourcesForParameters = true;
     });
 

The content of Request.Body is printed successfully.

Inference

The request body stream will be consumed when binding the model.

Other information

https://markb.uk/asp-net-core-read-raw-request-body-as-string.html

Conclusion

It is recommended to call EnableBuffering through middleware to solve the problem

Notes:

1. To avoid closing the StreamReader causing the Stream to be closed, you can solve this problem by leaveOpen: true
2. Reset Position = 0