C# Rest api - post list object is always null

Question

I'm using this code to post some object to my Rest API:

public static string Post<T>(string uri, T data, string contentType = "application/json", string method = "POST")
{
    byte[] dataBytes = Encoding.UTF8.GetBytes(JsonConvert.SerializeObject(data));
    string str = JsonConvert.SerializeObject(data);

    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);
    request.AutomaticDecompression = DecompressionMethods.GZip | DecompressionMethods.Deflate;
    request.ContentLength = dataBytes.Length;
    request.ContentType = contentType;
    request.Method = method;

    using (Stream requestBody = request.GetRequestStream())
    {
        requestBody.Write(dataBytes, 0, dataBytes.Length);
    }

    using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
    using (Stream stream = response.GetResponseStream())
    using (StreamReader reader = new StreamReader(stream))
    {
        return reader.ReadToEnd();
    }
} 

and the code works just fine when posting a simple object:

[Route("api/Name/{ActivationKey}")]
public async Task<HttpResponseMessage> Post([FromBody] SomeKindOfObject value, string ActivationKey)
{
    Some code...
}

But when I try posting a list of the same object I get null in the controller:

[Route("api/Name/{ActivationKey}")]
public async Task<HttpResponseMessage> Post([FromBody] List<SomeKindOfObject> value, string ActivationKey)
{
    Value is always null.
}

What could cause this and how can I fix it?

Answer 1

Try

public async Task<HttpResponseMessage> Post([FromBody] SomeKindOfObject[] value, string ActivationKey)

Desererialization can be contrary about its target container types, ie. list vs array vs collection.

Answer 2

Apparently the problem was that the list I tried to post was too big (more than 15k rows), what I did is splitting the list to shorter lists and posted every part alone and it worked.