Problem for generating C# client: "System.NotSupportedException: Collection format None is not supported.

Hello guys, I met a problem in order to generate a client thanks to autorest… Actually, I have correct swagger json definition (validated on online swagger editor -> 2.0.0) BUT An error is raised:

[14:26:57] Network Enabled: true
[14:26:58] The most recent installed version is 2.0.4168
[14:26:58] latest was not satisfied directly by a previous installation.
[14:26:58] Selected package: @microsoft.azure/autorest-core@2.0.4168 => ^2.0.4166
[14:26:58] AutoRest Core 2.0.4168 is available at C:\Users\lbabin\.autorest\@microsoft.azure_autorest-core@2.0.4168\node
_modules\@microsoft.azure\autorest-core
[14:26:58] Starting @microsoft.azure/autorest-core from C:\Users\lbabin\.autorest\@microsoft.azure_autorest-core@2.0.416
8
[14:26:58] Using core from: "C:\Users\lbabin\.autorest\@microsoft.azure_autorest-core@2.0.4168\node_modules\@microsoft.a
zure\autorest-core"
WARNING: The parameter --debug looks like it was meant for the new CLI! Note that you have invoked the legacy CLI (by us
ing at least one single-dash argument). Please visit https://github.com/Azure/autorest/blob/master/docs/user/cli.md for
information about the new CLI.
WARNING: The parameter --allow-no-input looks like it was meant for the new CLI! Note that you have invoked the legacy C
LI (by using at least one single-dash argument). Please visit https://github.com/Azure/autorest/blob/master/docs/user/cl
i.md for information about the new CLI.
FATAL: System.NotSupportedException: Collection format None is not supported.
   at AutoRest.CSharp.ClientModelExtensions.GetSeparator(CollectionFormat format) in C:\Users\ci\AppData\Local\Temp\PUBL
ISHv6236\30_20171011T220809\autorest.csharp\src\vanilla\ClientModelExtensions.cs:line 235
   at AutoRest.CSharp.ClientModelExtensions.GetFormattedReferenceValue(Parameter parameter, String clientReference) in C
:\Users\ci\AppData\Local\Temp\PUBLISHv6236\30_20171011T220809\autorest.csharp\src\vanilla\ClientModelExtensions.cs:line
210
   at AutoRest.CSharp.Model.MethodCs.BuildUrl(String variableName) in C:\Users\ci\AppData\Local\Temp\PUBLISHv6236\30_201
71011T220809\autorest.csharp\src\vanilla\Model\MethodCs.cs:line 389
   at AutoRest.CSharp.vanilla.Templates.Rest.Client.MethodTemplate.<ExecuteAsync>d1.MoveNext() in C:\Users\ci\AppData\Lo
cal\Temp\PUBLISHv6236\30_20171011T220809\autorest.csharp\src\obj\Razor\vanilla\Templates\Rest\Client\MethodTemplate.csht
ml:line 120
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at AutoRest.Core.Template"1.ToString()
   at AutoRest.CSharp.vanilla.Templates.Rest.Client.ServiceClientTemplate.<ExecuteAsync>d1.MoveNext() in C:\Users\ci\App
Data\Local\Temp\PUBLISHv6236\30_20171011T220809\autorest.csharp\src\obj\Razor\vanilla\Templates\Rest\Client\ServiceClien
tTemplate.cshtml:line 101
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at AutoRest.Core.CodeGenerator.<Write>d12.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at AutoRest.CSharp.CodeGeneratorCs.<GenerateClientSideCode>d8.MoveNext() in C:\Users\ci\AppData\Local\Temp\PUBLISHv62
36\30_20171011T220809\autorest.csharp\src\vanilla\CodeGeneratorCs.cs:line 60
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at AutoRest.CSharp.CodeGeneratorCs.<GenerateRestCode>d9.MoveNext() in C:\Users\ci\AppData\Local\Temp\PUBLISHv6236\30_
20171011T220809\autorest.csharp\src\vanilla\CodeGeneratorCs.cs:line 124
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at AutoRest.CSharp.CodeGeneratorCs.<Generate>d10.MoveNext() in C:\Users\ci\AppData\Local\Temp\PUBLISHv6236\30_2017101
1T220809\autorest.csharp\src\vanilla\CodeGeneratorCs.cs:line 157
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at AutoRest.CSharp.Program.<ProcessInternal>d4.MoveNext() in C:\Users\ci\AppData\Local\Temp\PUBLISHv6236\30_20171011T
220809\autorest.csharp\src\Program.cs:line 147
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at NewPlugin.<Process>d15.MoveNext()
FATAL: csharp/generate - FAILED
FATAL: Error: Plugin csharp reported failure.
Process() Cancelled due to exception : Plugin csharp reported failure.
Error: Plugin csharp reported failure.
    at CreatePluginExternal (C:\Users\lbabin\.autorest\@microsoft.azure_autorest-core@2.0.4168\node_modules\@microsoft.a
zure\autorest-core\dist\lib\pipeline\pipeline.js:91: 19)
    at <anonymous>
PS D:\ITESSO\Grammar\Json\Booking>

As you can see the problem is : “System.NotSupportedException: Collection format None is not supported.”. Do you have an idea? Thanks for your time 😃

[fearthecowboy]

The issue is that if you specify the query parameter as type:array, you have to tell autorest how the items are formatted. Add "collectionFormat": "csv" to the parameter definition.

Hmm. according to https://github.com/OAI/OpenAPI-Specification/blob/master/versions/2.0.md#parameter-object – csv is the default. Clearly, that’s not what we’re doing.

That’s a bug!

(still, add the "collectionFormat": "csv" to the parameter definition to work around it)

[MiYanni]

Workaround provided. Closing.