How to change Content-Type in Flurl?

Question

I have a .NET Core 2.0 WebApi application in which I have added the "Flurl.Http" (Version 2.1.0) NuGet package to my project.

I am trying to use Flurl to make a simple REST API call to one of Visual Studio Team Services' (VSTS) Api endpoints.

However, the particular VSTS api endpoint that I am calling requires that the Content-Type be set to "application/json-patch+json" instead of the typical "application/json".

In my Flurl call, I am using the "WithHeader()" method to try and set the Content-Type in the header of the request, but it is not working. Flurl seems to not allow me to override the default or standard Content-Type that is built into the PostJsonAsync method.

Does anyone know how to change the Content-Type of the request using Flurl? Or how to properly override the default behavior of the Content-Type in the Flurl configuration?

Thanks in advance!

My code:

public bool CreateNewBug(NewBugRequest newBugRequest)
{
    return _apiUrlToCreateNewBug.WithHeader("Authorization", "Basic Base64PersonalAccessTokenGoesHere")
                                .WithHeader("Content-Type", "application/json-patch+json")
                                .PostJsonAsync(newBugRequest.Fields)
                                .Result
                                .IsSuccessStatusCode;
}

(This code works, but the response from the VSTS api is that the Content-Type is not allowed and needs to be changed to "application/json-patch+json", which is what I tried to set it to in the header.)

Please take a minute and read [What are tags, and how should I use them?](https://stackoverflow.com/help/tagging) to avoid people skip over your questions when you stuff it with tags. — Tseng, Dec 06 '17 at 19:07

score 4 · Answer 1 · answered Apr 17 '18 at 02:17

4

New answer: Upgrade to the latest Flurl.Http. The issue has been fixed in 2.3.1, so the code posted in the question (the cleanest approach) should actually work as expected now.

answered Apr 17 '18 at 02:17

Todd Menier

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Todd Menier · Accepted Answer · 2018-04-17T02:18:55.437

UPDATE: The bug is fixed as of Flurl.Http 2.3.1, so this work-around is no longer necessary.

The short answer is I think you've discovered a bug. PostJsonAsync does set the Content-Type header, but I think it should leave it alone if you've already set it yourself. If you could report it here I should be able to get it fixed for the next release.

The work-around is fairly straightforward. You just need to take a couple extra steps to build the content and then post it using PostAsync instead of PostJsonAsync.

var json = FlurlHttp.GlobalSettings.JsonSerializer.Serialize(newBugRequest.Fields);
var content = new CapturedStringContent(json, Encoding.UTF8, "application/json-patch+json");

return _apiUrlToCreateNewBug
    .WithHeader("Authorization", "Basic Base64PersonalAccessTokenGoesHere")
    .PostAsync(content);

If you need to do this a lot, you could wrap it up in an extension method (PostJsonPatchAsync or similar) so you can call it fluently. See here for the correct way to do that.

Thanks so much! I ended up doing something very similar and was able to figure it out. I will post what I did shortly, as an answer to my own question. — Chase Harrison, Dec 08 '17 at 16:51
I created an issue for this https://github.com/tmenier/Flurl/issues/256 — Todd Menier, Dec 09 '17 at 16:09

score 0 · Answer 3 · answered Dec 08 '17 at 17:02

I was able to figure it out and find a working solution to my problem.

Here is the updated version of my working code:

public HttpResponseMessage CreateNewBug(NewBugRequest newBugRequest)
{
    return _apiUrlToCreateNewBug.AllowAnyHttpStatus()
                                .WithBasicAuth("", _personalAccessTokenForBasicAuth)
                                .PostAsync(new StringContent(JsonConvert.SerializeObject(newBugRequest.Fields), Encoding.UTF8, "application/json-patch+json"))
                                .Result;
}

The PostAsync method takes in an HttpContent object. HttpContent is an abstract class. Once I figured out all the concrete classes that implement the abstract class HttpContent, then I chose the one that best fit my situation and plugged it into the PostAsync method.

In this case, the StringContent class was the one that best fit what I needed. One of StringContent's constructors takes in the Content-Type as one of its parameters. So I passed in my custom Content-Type and everything worked as expected.

That's more or less the same solution. The main difference is that mine uses Flurl objects `CapturedStringContent`, which allows better diagnostics from `FlurlHttpException` because you have access to the request body, and `GlobalSettings`, just in case you made any tweaks to the default JSON searializer. — Todd Menier, Dec 09 '17 at 16:08

How to change Content-Type in Flurl?

3 Answers3