Making POST request to Vuforia's Web Services always results in "Fail", even though PUT request always works using same approach/body - rest

Question

I am developing an Android app in Unity. I am trying to make UnityWebRequests to work with Vuforia's Web Services API. Currently every method works - GET/PUT/DELETE, but I cannot POST anything, I always get an error:
Error:Generic/unknown HTTP error
Response code:400
Even though according to Vuforia's documentation POST requires the same request body as PUT and I am generating it using the same approach:
public string CreateNewUpdateBody(Text name, Text width, RawImage image, Toggle active_flag, Text application_metadata)
{
dynamic BodyData = new System.Dynamic.ExpandoObject();
if (!string.IsNullOrEmpty(name.text))
{
BodyData.name = name.text; // mandatory for post
}
if (!string.IsNullOrEmpty(width.text))
{
BodyData.width = float.Parse(width.text); // mandatory for post
}
if (image.texture != null)
{
Texture2D texture = (Texture2D)image.texture;
BodyData.image = System.Convert.ToBase64String(ImageConversion.EncodeToJPG(texture)); // mandatory for post
}
if (active_flag.interactable)
{
BodyData.active_flag = active_flag.isOn;
}
if (!string.IsNullOrEmpty(application_metadata.text))
{
BodyData.application_metadata = System.Convert.ToBase64String(System.Text.Encoding.UTF8.GetBytes(application_metadata.text));
}
string json = JsonConvert.SerializeObject(BodyData);
Debug.Log("Body data: " + json);
return json;
}
Then I send the web request like this:
private IEnumerator PostTarget(MonoBehaviour mono, string postBody)
{
var request = UnityWebRequest.Post(url + "/targets", postBody);
SetHeaders(request); // Must be done after setting the body
Debug.Log("Starting request " + request.method + " " + request.url);
yield return request.SendWebRequest();
while (!request.isDone) yield return null;
if (request.isHttpError || request.isNetworkError)
{
Debug.LogError("Request was not completed");
Debug.LogError("Error:" + request.error + " Response code:" + request.responseCode);
Debug.LogError(request.downloadHandler.text); // result_code is always just "Fail"
mono.StopAllCoroutines();
yield break;
}
else
{
Debug.Log("Request completed successfuly!");
Debug.Log(request.downloadHandler.text);
}
response = JsonUtility.FromJson<ResponsePostNewTarget>(request.downloadHandler.text);
Debug.Log("\nCreated target with id: " + response.target_id);
}
Any thoughts or suggestions? I appreciate the time you take to read this.

Answer 1

If everything works BUT posting data, either 1 vuforia doesn't support it or 2 (most likely) you're missing something.
Try adding this to your request
private UploadHandler GetUploadHandler(string postBody)
{
UploadHandler handler = new UploadHandlerRaw(System.Text.Encoding.UTF8.GetBytes(postBody));
handler.contentType = "application/json";
return handler;
}
And call it after SetHeaders
request.uploadHandler = GetUploadHandler(postBody);