Is there an equivalent to “HttpContext.Response.Write” in Asp.Net Core 2?

Question

I\'m trying to append some HTML and Javascript content on page using ActionFilter in Asp.Net Core 2.

In MVC, it\'s working with

Answer 1

You can try something like this

In a custom implementation of INopStartup.Configure(IApplicationBuilder application)

application.Use(async (context, next) =>    
{
    using (var customStream = new MemoryStream())
    {
        // Create a backup of the original response stream
        var backup = context.Response.Body;

        // Assign readable/writeable stream
        context.Response.Body = customStream;

        await next();

        // Restore the response stream
        context.Response.Body = backup;

        // Move to start and read response content
        customStream.Seek(0, SeekOrigin.Begin);
        var content = new StreamReader(customStream).ReadToEnd();

        // Write custom content to response
        await context.Response.WriteAsync(content);
    }
});

And than in your custom ResultFilterAttribute

public class MyAttribute : ResultFilterAttribute
{
    public override void OnResultExecuted(ResultExecutedContext context)
    {
        try
        {
            var bytes = Encoding.UTF8.GetBytes("Foo Bar");

            // Seek to end
            context.HttpContext.Response.Body.Seek(context.HttpContext.Response.Body.Length, SeekOrigin.Begin);
            context.HttpContext.Response.Body.Write(bytes, 0, bytes.Length);
        }
        catch
        {
            // ignored
        }

        base.OnResultExecuted(context);
    }
}

And the result

Hope this helps to get into the right way.

Answer 2

Response.Body.Write takes a byte array as an argument.

public void OnGet() {
    var text = "<h1>Hello, Response!</h1>";
    byte[] data = System.Text.Encoding.UTF8.GetBytes(text);
    Response.Body.Write(data, 0, data.Length);
}

or async version:

public async Task OnGetAsync() {
    var text = "<h1>Hello, Async Response!</h1>";
    byte[] data = System.Text.Encoding.UTF8.GetBytes(text);
    await Response.Body.WriteAsync(data, 0, data.Length);
}

Answer 3

The static and asynchronous method HttpResponseWritingExtensions.WriteAsync is currently the preferred way of reaching this goal.

Currently, you can find it in the assembly Assembly Microsoft.AspNetCore.Http.Abstractions.

using Microsoft.AspNetCore.Http;

[HttpGet("test")]
public async Task GetTest()
    => await HttpResponseWritingExtensions.WriteAsync(this.Response, "Hello World");