[Bug]: Exception on start after upgrade to latest

[LucaCris]

Describe the bug

Rollbacked to 6.5.0 due to non-sense exception:

[09:41:23 ERR] An unhandled exception has occurred while executing the request.
Swashbuckle.AspNetCore.SwaggerGen.SwaggerGeneratorException: Failed to generate schema for type - EagleChartModel.EChart. See inner exception
 ---> System.ArgumentException: The specified type System.Double must derive from the specific value's type System.Int32.
   at System.Text.Json.ThrowHelper.ThrowArgumentException_DeserializeWrongType(Type type, Object value)
   at System.Text.Json.JsonSerializer.ValidateInputType(Object value, Type inputType)
   at System.Text.Json.JsonSerializer.Serialize(Object value, Type inputType, JsonSerializerOptions options)
   at Swashbuckle.AspNetCore.SwaggerGen.JsonSerializerDataContractResolver.JsonConverterFunc(Object value, Type type)
   at Swashbuckle.AspNetCore.SwaggerGen.JsonSerializerDataContractResolver.<>c__DisplayClass2_0.<GetDataContractForType>b__1(Object value)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchemaForMember(Type modelType, SchemaRepository schemaRepository, MemberInfo memberInfo, DataProperty dataProperty)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.CreateObjectSchema(DataContract dataContract, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.<>c__DisplayClass11_0.<GenerateConcreteSchema>b__3()
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateReferencedSchema(DataContract dataContract, SchemaRepository schemaRepository, Func`1 definitionFactory)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateConcreteSchema(DataContract dataContract, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchemaForType(Type modelType, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchema(Type modelType, SchemaRepository schemaRepository, MemberInfo memberInfo, ParameterInfo parameterInfo, ApiParameterRouteInfo routeInfo)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.CreateArraySchema(DataContract dataContract, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.<>c__DisplayClass11_0.<GenerateConcreteSchema>b__1()
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateConcreteSchema(DataContract dataContract, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchemaForMember(Type modelType, SchemaRepository schemaRepository, MemberInfo memberInfo, DataProperty dataProperty)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.CreateObjectSchema(DataContract dataContract, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.<>c__DisplayClass11_0.<GenerateConcreteSchema>b__3()
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateReferencedSchema(DataContract dataContract, SchemaRepository schemaRepository, Func`1 definitionFactory)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateConcreteSchema(DataContract dataContract, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchemaForParameter(Type modelType, SchemaRepository schemaRepository, ParameterInfo parameterInfo, ApiParameterRouteInfo routeInfo)
   at Swashbuckle.AspNetCore.SwaggerGen.SchemaGenerator.GenerateSchema(Type modelType, SchemaRepository schemaRepository, MemberInfo memberInfo, ParameterInfo parameterInfo, ApiParameterRouteInfo routeInfo)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateSchema(Type type, SchemaRepository schemaRepository, PropertyInfo propertyInfo, ParameterInfo parameterInfo, ApiParameterRouteInfo routeInfo)
   --- End of inner exception stack trace ---
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateSchema(Type type, SchemaRepository schemaRepository, PropertyInfo propertyInfo, ParameterInfo parameterInfo, ApiParameterRouteInfo routeInfo)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOpenApiOperationFromMetadata(ApiDescription apiDescription, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOperation(ApiDescription apiDescription, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GenerateOperations(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GeneratePaths(IEnumerable`1 apiDescriptions, SchemaRepository schemaRepository)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwaggerDocumentWithoutFilters(String documentName, String host, String basePath)
   at Swashbuckle.AspNetCore.SwaggerGen.SwaggerGenerator.GetSwaggerAsync(String documentName, String host, String basePath)
   at Swashbuckle.AspNetCore.Swagger.SwaggerMiddleware.Invoke(HttpContext httpContext, ISwaggerProvider swaggerProvider)   at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddlewareImpl.Invoke(HttpContext context)
[09:41:23 INF] Request finished HTTP/1.1 GET http://localhost:5500/swagger/v1/swagger.json - 500 null text/plain; charset=utf-8 84.4112ms

Expected behavior

As in 6.5.0 the standard swagger page.

Actual behavior

No response

Steps to reproduce

No response

Exception(s) (if any)

No response

Swashbuckle.AspNetCore version

6.6.1

.NET Version

net 8.0.5

Anything else?

No response

[martincostello]

Please provide a minimal reproducible example as a GitHub repository that demonstrates the issue you're experiencing so we can look into this further.

[IvanMaskaliou]

I have the same issue/exception. But I think I found how to workaround it - I have a property defined like:

[DataMember]
[Required]
[DefaultValue(1)]
public double Factor { get; set; } = 1;

and I have that exception in 6.6.1 (not in 6.5.0).
But if I remove DefaultValue attribute or set it as [DefaultValue(1D)] (explicit double instead of int) it is working fine.

[martincostello]

Interesting - what version of .NET are you using?

I wonder if this is something to do with changes in .NET 8 that Swashbuckle is now consuming because we have a net8.0 target now.

[IvanMaskaliou]

.NET 8.0.5

[martincostello]

Is it possible you could provide a stack trace that includes our line numbers when the exception happens?

I think the changes for #2800 is what's making this issue appear, I'm just having trouble reconciling exactly which code path it's going down when it hits that.

I'll try debugging things with the sample you've given me anyway as that will probably point to what's going wrong.

[martincostello]

I've gotten a repro for this based on #2885 (comment) now, thanks.

[LucaCris]

I also have the same scheme:

    [XmlAttribute]
    [DefaultValue(0)]
    public double ParamVal1 { get; set; }

Not yet tested the workaround above.