Issue creating HttpClient helper method

Question

I have a functioning async Task that calls a web service:

private async Task GetResult()
{
   using (var client = new HttpClient())
   {
      client.BaseAddress = new Uri(_baseAddress);
      client.DefaultRequestHeaders.Accept.Clear();
      client.DefaultRequestHeaders.Accept.Add(
         new MediaTypeWithQualityHeaderValue("application/json"));
      client.DefaultRequestHeaders.Add("Username", _username);
      client.DefaultRequestHeaders.Add("Action", "GET");
      /* etc */
      var response = await client.GetAsync(client.BaseAddress);
   }
}

I would like to separate out the creation of the HttpClient object so it can be parameterized and reused:

private async Task GetResult()
{
   using (var client = GetClient(_baseAddress, _username))
   {
      var response = await client.GetAsync(client.BaseAddress);
   }
}
private static HttpClient GetClient(string Address, string Username)
{
   using (var client = new HttpClient())
   {
      client.BaseAddress = new Uri(Address);
      client.DefaultRequestHeaders.Accept.Clear();
      client.DefaultRequestHeaders.Accept.Add(
         new MediaTypeWithQualityHeaderValue("application/json"));
      client.DefaultRequestHeaders.Add("Username", Username);
      client.DefaultRequestHeaders.Add("Action", "GET");
      /* etc */
      return client;
   }
}

While this appears functionally identical to me, the latter throws an AggregateException error with inner exception

Cannot Access a disposed object. Object name: 'System.Net.Http.HttpClient'.

Perhaps there is some async subtlety that I don't understand?

Answer 1

Get rid of the using inside of GetClient. You only use using for things that remain "in your ownership", you are "giving up ownership to the caller" when you return client;.

It is now the caller's resposability to use a using statement (which you do already correctly do in GetResult).

This has nothing to do with asnyc and is simply standard IDisposable behavior.