Add custom header in an After Hook

[Matias-Barrios]

Hi Guys,

I am trying to add a custom header to each response my app is returning. I added this code in the startup.cs file but I'm getting an error stating the response already started :

 public void Configure(IApplicationBuilder app, IHostingEnvironment env)
       {
           app.UseExceptionHandler("/errorhandler");
           app.UseCarter(new CarterOptions(after: ctx => HeaderInjector(ctx)));
       }
       public Task HeaderInjector(HttpContext context)
       {
           context.Response.Headers.Add("x-gamecentral-received", "game1");
           return Task.CompletedTask;
       }

Am I doing something wrong?

[jchannon]

Afraid not, if you have returned a response we don't wrap it then issue a response, ASP.NET Core spots response has started and won't allow modification, best bet is to set a response header in the Before hook

On Thu, 24 Oct 2019 at 19:51, Matias.Barrios notifications@github.com wrote:

Hi Guys,

I am trying to add a custom header to each response my app is returning. I added this code in the startup.cs file but I'm getting an error stating the response already started :

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
app.UseExceptionHandler("/errorhandler");
app.UseCarter(new CarterOptions(after: ctx => HeaderInjector(ctx)));
}
public Task HeaderInjector(HttpContext context)
{
context.Response.Headers.Add("x-gamecentral-received", "game1");
return Task.CompletedTask;
}

Am I doing something wrong?

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[Matias-Barrios]

Thanks for your response. Now my code changed to this :

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            app.UseExceptionHandler("/errorhandler");
            app.UseCarter(new CarterOptions(before: ctx => HeaderInjector(ctx)));

        }
        private Task<bool> HeaderInjector(HttpContext ctx)
        {
            ctx.Request.Headers["x-gamecentral-received"] = "game1";
            return Task.FromResult(true);
        }

And I don't get any errors anymore. But I don't see the header on the response. I have tested this in a simple endpoint that basically replies with "Healthy!"

[jchannon]

You've set the request headers not the response ;)

On Thu, 24 Oct 2019 at 20:14, Matias.Barrios notifications@github.com wrote:

Thanks for your response. Now my code changed to this :

public void Configure(IApplicationBuilder app, IHostingEnvironment env) { app.UseExceptionHandler("/errorhandler"); app.UseCarter(new CarterOptions(before: ctx => HeaderInjector(ctx)));

    }
    private Task<bool> HeaderInjector(HttpContext ctx)
    {
        ctx.Request.Headers["x-gamecentral-received"] = "game1";
        return Task.FromResult(true);
    }

And I don't get any errors anymore. But I don't see the header on the response. I have tested this in a simple endpoint that basically replies with "Healthy!"

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[Matias-Barrios]

@jchannon Thanks so much! Now its working!

[jchannon]

No probs :)

On Thu, 24 Oct 2019 at 20:28, Matias.Barrios notifications@github.com wrote:

Closed #209 https://github.com/CarterCommunity/Carter/issues/209.

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