Redirect to URL with POST method in Asp.Net Core

Question

I have simple url rewriter:

    private static void RedirectToAPI(RewriteContext context)
    {
        var request = context.HttpContext.Request;
        if (request.Path.Value.StartsWith("/apiendpoint", StringComparison.OrdinalIgnoreCase))
        {           
            var json = JsonConvert.SerializeObject(request.Path.Value
                .Split(new char[] { '/' }, StringSplitOptions.RemoveEmptyEntries)
                .Skip(1));
            var response = context.HttpContext.Response;

            response.Headers[HeaderNames.Location] = $"/custom";
            response.StatusCode = StatusCodes.Status301MovedPermanently;
            context.Result = RuleResult.EndResponse;
            using (var bodyWriter = new StreamWriter(response.Body))
            {
                bodyWriter.Write(json);
                bodyWriter.Flush();
            }
        }
    }

The problem is, when it redirects to /custom url, request has method GET, while this method require POST.

For example, send GET request to url /apiendpoint/first/second/third, then rewriter responds to redirect, accordingly, the following request must be with method POST, but now, it is GET.

How can I change method of request, which is after url rewriter response?

user_3839724 · Answer

Can you set @juunas answer as a correct answer, his answer solved it for me as you can see in my example code.

internal class RedirectCultureRule : IRule
{
    private const string CultureKey = "culture";

    public void ApplyRule(RewriteContext context)
    {
        HttpRequest httpRequest = context.HttpContext.Request;
        httpRequest.Query.TryGetValue(CultureKey, out StringValues cultureValues);
        string culture = cultureValues;

        if (cultureValues.Count > 0 && culture.IsCultureMatch())
        {
            context.Result = RuleResult.ContinueRules;
            return;
        }

        Dictionary queryParts = new Dictionary();
        NameValueCollection queryString = HttpUtility.ParseQueryString(httpRequest.QueryString.ToString());

        foreach (string key in queryString)
        {
            queryParts[key.Trim()] = queryString[key].Trim();
        }

        if (!queryParts.ContainsKey(CultureKey))
        {
            queryParts[CultureKey] = CultureInfo.CurrentCulture.Name;
        }

        string query = $"?{string.Join("&", queryParts.Select(qp => $"{qp.Key}={qp.Value}"))}";

        if (query.Length > 1)
        {
            httpRequest.QueryString = new QueryString(query);
        }

        string url = UriHelper.GetDisplayUrl(httpRequest);

        HttpResponse httpResponse = context.HttpContext.Response;
        httpResponse.StatusCode = 308;
        httpResponse.Headers[HeaderNames.Location] = url;

        using (StreamReader requestReader = new StreamReader(httpRequest.Body))
        {
            using (StreamWriter responseWriter = new StreamWriter(httpResponse.Body))
            {
                string body = requestReader.ReadToEnd();
                responseWriter.Write(body);
                responseWriter.Flush();
            }
        }

        context.Result = RuleResult.EndResponse;
    }
}

user_7462495 · Answer

If using ASP.NET Core 2.0 there is RedirectPermanentPreserveMethod, you can read about it here. If this method is not supported you can try doing it manually.

Redirect to URL with POST method in Asp.Net Core

4 Answers