NSwag: Bug in Error serialization openapi2csclient

my yaml:

    Error:
      type: object
      properties:
        code:
          $ref: '#/components/schemas/ErrorCode'
        description:
          type: string
    Errors:
      type: object
      properties:
        errors:
          type: array
          items:
            $ref: '#/components/schemas/Error'
    ErrorCode:
      description: Enum of errors
      type: string
      enum:
        - NOTFOUND
        - GENERAL_EXCEPTION

service I am calling returns this:

{
    "errors": [
        {
            "code": "GENERAL_EXCEPTION",
            "description": "03396370-ddc4-41c4-ae03-ed07249a9d1b - Not supported yet."
        }
    ]
}

I cannot get serialized object Errors in proper format with current error handling. This is current generated c# code

     if (status_ == "500") 
                        {
                            var objectResponse_ = await ReadJsonObjectResponseAsync<Errors>(response_, headers_).ConfigureAwait(false);
                            throw new ApiException<Errors>("Error", (int)response_.StatusCode, objectResponse_.Text, headers_, objectResponse_.Object, null);
                        }

objectResponse_ contains Errors object which is what I get from service I am calling but Text property is empty and the Errors object is not seriliazed correctly

this used to work in my previously generated code:

                       if (status_ == "500") 
                        {
                            var responseData_ = response_.Content == null ? null : await response_.Content.ReadAsStringAsync().ConfigureAwait(false); 
                            var result_ = default(Errors); 
                            try
                            {
                                result_ = Newtonsoft.Json.JsonConvert.DeserializeObject<Errors>(responseData_, _settings.Value);
                            } 
                            catch (System.Exception exception_) 
                            {
                                throw new SwaggerException("Could not deserialize the response body.", (int)response_.StatusCode, responseData_, headers_, exception_);
                            }
                            throw new SwaggerException<Errors>("Errors", (int)response_.StatusCode, responseData_, headers_, result_, null);
                        }

About this issue

Original URL
State: closed
Created 5 years ago
Comments: 19 (15 by maintainers)

Most upvoted comments

@rars Oh, I see there’s a new NSwag template Client.Class.Constructor that you can override (so you don’t need any other *.liquid templates) to set the property - that’s probably the best approach.

daiplusplus on Aug 19, 2019

@rars

There are several options.

The simplest is to set ReadResponseAsString in a partial method - which requires adding partial class declarations in another file and keeping it in-sync with the NSwag-generated clients. The ProcessResponse partial method is the best place to set ReadResponseAsString as it’s always called right before deserialization:

public partial class BooksClient
{
    partial void ProcessResponse(HttpClient client, HttpResponseMessage response)
    {
        this.ReadResponseAsString = false;
    }
}
public partial class VideosClient
{
    partial void ProcessResponse(HttpClient client, HttpResponseMessage response)
    {
        this.ReadResponseAsString = false;
    }
}
public partial class TeaClient
{
    partial void ProcessResponse(HttpClient client, HttpResponseMessage response)
    {
        this.ReadResponseAsString = false;
    }
}
// etc

Another approach, which uses MEDI, and is documented by Microsoft as the prescribed way for customizing registered typed-clients is to use ITypedHttpClientFactory.

Unfortunately because the ReadResponseAsString property isn’t attached to any superclass or interface we can’t use a common factory method for all of your typed clients - also you’ll need to reimplement ITypedHttpClientFactory - which is a pain. And I won’t go into details here.

I think the best approach here is to override the Liquid template that NSwag is using to generate a client class constructor that sets the this.ReadResponseAsString = false;

…or just subclass all of the typed clients and set the property there:

class BooksClient2 : BooksClient
{
    public BooksClient( HttpClient httpClient ) : base( httpClient )
    {
        this.ReadResponseAsString = false;
    }
}

void RegisterClients(IServiceCollection serviceCollection)
{
    services.AddHttpClient<IBooksClient, BooksClient2>(
        httpClient => httpClient.BaseAddress = "https://books.com/api");`
}

…which is about the same amount of effort as using partial classes.

@RicoSuter I think the option to use ReadResponseAsString should be a configurable option in NSwag client generation options - as well as adding an optional interface ITypedClient that exposes common members to external consumers, such as the ReadResponseAsString property.

daiplusplus on Aug 19, 2019

On the generated client class

RicoSuter on Aug 16, 2019