Even though this solution might seem obvious, I just wanted to post it here so the next guy will google it faster.
If you still want to have the model as a parameter in the method, you can create a DelegatingHandler to buffer the content.
internal sealed class BufferizingHandler : DelegatingHandler
{
protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
{
await request.Content.LoadIntoBufferAsync();
var result = await base.SendAsync(request, cancellationToken);
return result;
}
}
And add it to the global message handlers:
configuration.MessageHandlers.Add(new BufferizingHandler());
This solution is based on the answer by Darrel Miller.
This way all the requests will be buffered.