Improving performance

I’ve been using NSwag for some time now, and have been browsing the generated code on more than one occasion. Today I was made aware of a some work David Fowler is doing to educate the community on best practices around async code. One of his ‘bad’ examples rang a bell.

Assuming your code generation hasn’t undergone major changes recently, NSwag generates code like this:

var responseData_ = response_.Content == null ? null : await response_.Content.ReadAsStringAsync().ConfigureAwait(false);
var result_ = default(AcceptanceReply);
try
{
      result_ = Newtonsoft.Json.JsonConvert.DeserializeObject<AcceptanceReply>(responseData_, _settings.Value);
      return result_;
 }
catch (System.Exception exception_)
{
      throw new SwaggerException("Could not deserialize the response body.", (int)response_.StatusCode, responseData_, headers_, exception_);
}

The whole string is read into memory before it gets deserialized into an object.

Fowler is suggesting this improved approach: https://github.com/davidfowl/AspNetCoreDiagnosticScenarios/blob/master/Scenarios/Services/PokemonService.cs#L36

public async Task<PokemonData> GetPokemonAsync()
{
      var response = await _client.GetAsync(_url);
      // This is a hack to work around the fact that this JSON api returns text/plain
      response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
      // Use the built in methods to read the response as JSON
      return await response.Content.ReadAsAsync<PokemonData>();
 }

[daiplusplus]

@juanperezADD I was able to implement the change by creating my own .liquid templates and putting them in a directory specified in NSwagStudio. I’ll need to polish them up and remove proprietary bits before I can share them here though.

[daiplusplus]

Nice, maybe you also sync with @Jehoel here: #1697

That’s me 😃