NSwag
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Published
20 hours ago •
RicoSuter
RicoSuter
Generates wrong request media type for corresponding deserializer when multiple response content possible.
I have tested this with both the C# and TypeScript generators and both have the same behavior.
If a swagger.json file has multiple response content types and the first content type is text/plain then the wrong deserializer is used.
In the example C# you see on line 76 request_.Headers.Accept.Add(System.Net.Http.Headers.MediaTypeWithQualityHeaderValue.Parse("text/plain")); it is sending text/plain in the request, so of course the server is going to response with a text/plain body.
But then on line 101 var objectResponse_ = await ReadObjectResponseAsync<string>(response_, headers_, cancellationToken).ConfigureAwait(false); it is using the Json deserializer instead of the correct response_.Content.ReadAsStringAsync().
Example swagger.json
{
"openapi": "3.0.1",
"info": {
"title": "ExampleService",
"version": "1.0.0"
},
"paths": {
"/TestString": {
"get": {
"tags": [
"Example"
],
"responses": {
"200": {
"description": "Success",
"content": {
"text/plain": {
"schema": {
"type": "string"
}
},
"application/json": {
"schema": {
"type": "string"
}
},
"text/json": {
"schema": {
"type": "string"
}
}
}
}
}
}
}
},
"components": { }
}
Example generate C# file
//----------------------
// <auto-generated>
// Generated using the NSwag toolchain v13.14.5.0 (NJsonSchema v10.5.2.0 (Newtonsoft.Json v12.0.0.0)) (http://NSwag.org)
// </auto-generated>
//----------------------
#pragma warning disable 108 // Disable "CS0108 '{derivedDto}.ToJson()' hides inherited member '{dtoBase}.ToJson()'. Use the new keyword if hiding was intended."
#pragma warning disable 114 // Disable "CS0114 '{derivedDto}.RaisePropertyChanged(String)' hides inherited member 'dtoBase.RaisePropertyChanged(String)'. To make the current member override that implementation, add the override keyword. Otherwise add the new keyword."
#pragma warning disable 472 // Disable "CS0472 The result of the expression is always 'false' since a value of type 'Int32' is never equal to 'null' of type 'Int32?'
#pragma warning disable 1573 // Disable "CS1573 Parameter '...' has no matching param tag in the XML comment for ...
#pragma warning disable 1591 // Disable "CS1591 Missing XML comment for publicly visible type or member ..."
#pragma warning disable 8073 // Disable "CS8073 The result of the expression is always 'false' since a value of type 'T' is never equal to 'null' of type 'T?'"
#pragma warning disable 3016 // Disable "CS3016 Arrays as attribute arguments is not CLS-compliant"
namespace OpenApiExample
{
using System = global::System;
[System.CodeDom.Compiler.GeneratedCode("NSwag", "13.14.5.0 (NJsonSchema v10.5.2.0 (Newtonsoft.Json v12.0.0.0))")]
public partial class ExampleClient
{
private string _baseUrl = "";
private System.Net.Http.HttpClient _httpClient;
private System.Lazy<Newtonsoft.Json.JsonSerializerSettings> _settings;
public ExampleClient(string baseUrl, System.Net.Http.HttpClient httpClient)
{
BaseUrl = baseUrl;
_httpClient = httpClient;
_settings = new System.Lazy<Newtonsoft.Json.JsonSerializerSettings>(CreateSerializerSettings);
}
private Newtonsoft.Json.JsonSerializerSettings CreateSerializerSettings()
{
var settings = new Newtonsoft.Json.JsonSerializerSettings();
UpdateJsonSerializerSettings(settings);
return settings;
}
public string BaseUrl
{
get { return _baseUrl; }
set { _baseUrl = value; }
}
protected Newtonsoft.Json.JsonSerializerSettings JsonSerializerSettings { get { return _settings.Value; } }
partial void UpdateJsonSerializerSettings(Newtonsoft.Json.JsonSerializerSettings settings);
partial void PrepareRequest(System.Net.Http.HttpClient client, System.Net.Http.HttpRequestMessage request, string url);
partial void PrepareRequest(System.Net.Http.HttpClient client, System.Net.Http.HttpRequestMessage request, System.Text.StringBuilder urlBuilder);
partial void ProcessResponse(System.Net.Http.HttpClient client, System.Net.Http.HttpResponseMessage response);
/// <returns>Success</returns>
/// <exception cref="ApiException">A server side error occurred.</exception>
public System.Threading.Tasks.Task<string> TestStringAsync()
{
return TestStringAsync(System.Threading.CancellationToken.None);
}
/// <param name="cancellationToken">A cancellation token that can be used by other objects or threads to receive notice of cancellation.</param>
/// <returns>Success</returns>
/// <exception cref="ApiException">A server side error occurred.</exception>
public async System.Threading.Tasks.Task<string> TestStringAsync(System.Threading.CancellationToken cancellationToken)
{
var urlBuilder_ = new System.Text.StringBuilder();
urlBuilder_.Append(BaseUrl != null ? BaseUrl.TrimEnd('/') : "").Append("/TestString");
var client_ = _httpClient;
var disposeClient_ = false;
try
{
using (var request_ = new System.Net.Http.HttpRequestMessage())
{
request_.Method = new System.Net.Http.HttpMethod("GET");
request_.Headers.Accept.Add(System.Net.Http.Headers.MediaTypeWithQualityHeaderValue.Parse("text/plain"));
PrepareRequest(client_, request_, urlBuilder_);
var url_ = urlBuilder_.ToString();
request_.RequestUri = new System.Uri(url_, System.UriKind.RelativeOrAbsolute);
PrepareRequest(client_, request_, url_);
var response_ = await client_.SendAsync(request_, System.Net.Http.HttpCompletionOption.ResponseHeadersRead, cancellationToken).ConfigureAwait(false);
var disposeResponse_ = true;
try
{
var headers_ = System.Linq.Enumerable.ToDictionary(response_.Headers, h_ => h_.Key, h_ => h_.Value);
if (response_.Content != null && response_.Content.Headers != null)
{
foreach (var item_ in response_.Content.Headers)
headers_[item_.Key] = item_.Value;
}
ProcessResponse(client_, response_);
var status_ = (int)response_.StatusCode;
if (status_ == 200)
{
var objectResponse_ = await ReadObjectResponseAsync<string>(response_, headers_, cancellationToken).ConfigureAwait(false);
if (objectResponse_.Object == null)
{
throw new ApiException("Response was null which was not expected.", status_, objectResponse_.Text, headers_, null);
}
return objectResponse_.Object;
}
else
{
var responseData_ = response_.Content == null ? null : await response_.Content.ReadAsStringAsync().ConfigureAwait(false);
throw new ApiException("The HTTP status code of the response was not expected (" + status_ + ").", status_, responseData_, headers_, null);
}
}
finally
{
if (disposeResponse_)
response_.Dispose();
}
}
}
finally
{
if (disposeClient_)
client_.Dispose();
}
}
protected struct ObjectResponseResult<T>
{
public ObjectResponseResult(T responseObject, string responseText)
{
this.Object = responseObject;
this.Text = responseText;
}
public T Object { get; }
public string Text { get; }
}
public bool ReadResponseAsString { get; set; }
protected virtual async System.Threading.Tasks.Task<ObjectResponseResult<T>> ReadObjectResponseAsync<T>(System.Net.Http.HttpResponseMessage response, System.Collections.Generic.IReadOnlyDictionary<string, System.Collections.Generic.IEnumerable<string>> headers, System.Threading.CancellationToken cancellationToken)
{
if (response == null || response.Content == null)
{
return new ObjectResponseResult<T>(default(T), string.Empty);
}
if (ReadResponseAsString)
{
var responseText = await response.Content.ReadAsStringAsync().ConfigureAwait(false);
try
{
var typedBody = Newtonsoft.Json.JsonConvert.DeserializeObject<T>(responseText, JsonSerializerSettings);
return new ObjectResponseResult<T>(typedBody, responseText);
}
catch (Newtonsoft.Json.JsonException exception)
{
var message = "Could not deserialize the response body string as " + typeof(T).FullName + ".";
throw new ApiException(message, (int)response.StatusCode, responseText, headers, exception);
}
}
else
{
try
{
using (var responseStream = await response.Content.ReadAsStreamAsync().ConfigureAwait(false))
using (var streamReader = new System.IO.StreamReader(responseStream))
using (var jsonTextReader = new Newtonsoft.Json.JsonTextReader(streamReader))
{
var serializer = Newtonsoft.Json.JsonSerializer.Create(JsonSerializerSettings);
var typedBody = serializer.Deserialize<T>(jsonTextReader);
return new ObjectResponseResult<T>(typedBody, string.Empty);
}
}
catch (Newtonsoft.Json.JsonException exception)
{
var message = "Could not deserialize the response body stream as " + typeof(T).FullName + ".";
throw new ApiException(message, (int)response.StatusCode, string.Empty, headers, exception);
}
}
}
private string ConvertToString(object value, System.Globalization.CultureInfo cultureInfo)
{
if (value == null)
{
return "";
}
if (value is System.Enum)
{
var name = System.Enum.GetName(value.GetType(), value);
if (name != null)
{
var field = System.Reflection.IntrospectionExtensions.GetTypeInfo(value.GetType()).GetDeclaredField(name);
if (field != null)
{
var attribute = System.Reflection.CustomAttributeExtensions.GetCustomAttribute(field, typeof(System.Runtime.Serialization.EnumMemberAttribute))
as System.Runtime.Serialization.EnumMemberAttribute;
if (attribute != null)
{
return attribute.Value != null ? attribute.Value : name;
}
}
var converted = System.Convert.ToString(System.Convert.ChangeType(value, System.Enum.GetUnderlyingType(value.GetType()), cultureInfo));
return converted == null ? string.Empty : converted;
}
}
else if (value is bool)
{
return System.Convert.ToString((bool)value, cultureInfo).ToLowerInvariant();
}
else if (value is byte[])
{
return System.Convert.ToBase64String((byte[]) value);
}
else if (value.GetType().IsArray)
{
var array = System.Linq.Enumerable.OfType<object>((System.Array) value);
return string.Join(",", System.Linq.Enumerable.Select(array, o => ConvertToString(o, cultureInfo)));
}
var result = System.Convert.ToString(value, cultureInfo);
return result == null ? "" : result;
}
}
[System.CodeDom.Compiler.GeneratedCode("NSwag", "13.14.5.0 (NJsonSchema v10.5.2.0 (Newtonsoft.Json v12.0.0.0))")]
public partial class ApiException : System.Exception
{
public int StatusCode { get; private set; }
public string Response { get; private set; }
public System.Collections.Generic.IReadOnlyDictionary<string, System.Collections.Generic.IEnumerable<string>> Headers { get; private set; }
public ApiException(string message, int statusCode, string response, System.Collections.Generic.IReadOnlyDictionary<string, System.Collections.Generic.IEnumerable<string>> headers, System.Exception innerException)
: base(message + "\n\nStatus: " + statusCode + "\nResponse: \n" + ((response == null) ? "(null)" : response.Substring(0, response.Length >= 512 ? 512 : response.Length)), innerException)
{
StatusCode = statusCode;
Response = response;
Headers = headers;
}
public override string ToString()
{
return string.Format("HTTP Response: \n\n{0}\n\n{1}", Response, base.ToString());
}
}
[System.CodeDom.Compiler.GeneratedCode("NSwag", "13.14.5.0 (NJsonSchema v10.5.2.0 (Newtonsoft.Json v12.0.0.0))")]
public partial class ApiException<TResult> : ApiException
{
public TResult Result { get; private set; }
public ApiException(string message, int statusCode, string response, System.Collections.Generic.IReadOnlyDictionary<string, System.Collections.Generic.IEnumerable<string>> headers, TResult result, System.Exception innerException)
: base(message, statusCode, response, headers, innerException)
{
Result = result;
}
}
}
#pragma warning restore 1591
#pragma warning restore 1573
#pragma warning restore 472
#pragma warning restore 114
#pragma warning restore 108
#pragma warning restore 3016
I'm experiencing similar issue in a sample based on PetStore v3. The /pet/findByStatus endpoint is a good example.
The problem appears to occur when an operation can return multiple content types and the first in that collection is not "application/json".
Looking over the code base, I think the problem may lie in NSwag.CodeGeneration.Models.OperationModelBase.Produces property. The evaluation in pseudo-code is something like:
"If the operation's actual produces contains 'application/json' then use 'application/json'. Otherwise, use the first non-null 'produces' in this order:
- the operation's first actual produces
- the first Success response's produces
- 'application/json'"
A solution may be to include the operation's Success responses in the first evaluation, as well:
"If the operation's actual produces contains 'application/json' or any of the success responses produce 'application/json' then use 'application/json'. Otherwise, use the first non-null 'produces' in this order: ..."
public string Produces
{
get
{
if (_operation.ActualProduces?.Contains("application/json") == true || Responses.Any(r => r.IsSuccess && r.Produces == "application/json"))
{
return "application/json";
}
return _operation.ActualProduces?.FirstOrDefault() ??
SuccessResponse?.Produces ??
"application/json";
}
}
Related: https://github.com/RicoSuter/NSwag/issues/3825 https://github.com/RicoSuter/NSwag/issues/2676
