Http Post to .net isolated azure function Body Empty (most) of the time

Question

I am executing the following:

HttpClient _httpClient= new HttpClient
{
   BaseAddress = new Uri("http://localhost:7071/api/"), // Local
   Timeout = TimeSpan.FromSeconds(60)
};
_httpClient.DefaultRequestHeaders.Accept.Clear();
_httpClient.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

 var stopMessage = new Domain.StopMessage
    {
    SiteId = "SiteId",
    };

 var response = await _httpClient.PostAsJsonAsync("StopMessage", stopMessage);

Against this function:

    [Function("StopMessage")]
    public async Task<HttpResponseData> Run([HttpTrigger(AuthorizationLevel.Anonymous, "post")] HttpRequestData req, FunctionContext executionContext)
    {
        var log = executionContext.GetLogger(nameof(StopMessage));
        try
        {
            DateTime currentDate = DateTime.Now;
            string requestBody = string.Empty;
            using (StreamReader streamReader = new StreamReader(req.Body))
            {
                requestBody = await streamReader.ReadToEndAsync();
            }

I am using a .net isolated function. Here is my host.json:

{
  "version": "2.0",
  "logging": {
    "applicationInsights": {
      "samplingSettings": {
        "isEnabled": true,
        "excludedTypes": "Request"
      }
    }
  },
  "functionTimeout": "00:05:00",
  "extensions": {
    "eventHubs": {
      "batchCheckpointFrequency": 5,
      "eventProcessorOptions": {
        "maxBatchSize": 256,
        "prefetchCount": 512
      },
      "initialOffsetOptions": {
        "type": "fromEnqueuedTime",
        "enqueuedTimeUtc": "2021-11-01T00:00Z"
      }
    }
  },
  // Configuration settings for Singleton lock behavior. (Optional)
  "singleton": {
    // The period that function level locks are taken for (they will auto renew)
    "lockPeriod": "00:01:00"
  }
}

75% of the time requestBody is empty and the transfer is not made. I can repeat send the same request multiple times and sometimes it will populate the body and sometimes it won't. How can I make it that it the body is always present?

Answer 1

The issue seem to be between _httpClient.PostAsJsonAsync("StopMessage", stopMessage); and HttpRequestData

I can not give you the reason to why this issue occours.

But if JsonSerializer.Serialize is used it seems to work fine.

string json = JsonSerializer.Serialize(stopMessage);

var httpResponseMessage = await _httpClient.PostAsync("StopMessage", new StringContent(json));