QueryParameters Enum in Uri - Exception Illegal class passed as substitution

[infokomes]

Info:
"kiotaVersion": "1.8.2",
"language": "CSharp",
"usesBackingStore": false,
"excludeBackwardCompatible": false,
"includeAdditionalData": false,

PackageReference:

<PackageReference Include="Microsoft.Kiota.Abstractions" Version="1.7.0" />
<PackageReference Include="Microsoft.Kiota.Http.HttpClientLibrary" Version="1.3.0" />
<PackageReference Include="Microsoft.Kiota.Serialization.Form" Version="1.1.0" />
<PackageReference Include="Microsoft.Kiota.Serialization.Json" Version="1.1.1" />
<PackageReference Include="Microsoft.Kiota.Authentication.Azure" Version="1.1.1" />
<PackageReference Include="Microsoft.Kiota.Serialization.Text" Version="1.1.0" />
<PackageReference Include="Microsoft.Kiota.Serialization.Multipart" Version="1.1.0" />

Method URI return Exception:
return new Uri(UriTemplate.Expand(UrlTemplate, dictionary));

System.ArgumentException
HResult=0x80070057
Message=Illegal class passed as substitution, found ...GetFormatQueryParameterType at col:62
Source=Std.UriTemplate
StackTrace:
at Std.UriTemplate.GetSubstitutionType(Object value, Int32 col)

class :

  public enum GetFormatQueryParameterType {
       [EnumMember(Value = "metadata")]
       Metadata,
       [EnumMember(Value = "minimal")]
       Minimal,
   }

schema openapi: 3.0.3:

  - name: format
    in: query
    schema:
      type: string
      enum: [metadata, minimal]
      default:
        minimal

[baywet]

Hi @infokomes,
Thanks for reporting this.
I think this is a side effect of #2490 and associated PRs.

@andreaTP std uri template is unhappy because kiota abstractions is passing it enums values or arrays of enum values.
I believe the right solution would be for kiota abstractions to do the conversion to string or array of string before passing the context to std URI template.
That's because the code symbols (enum members) and query/path parameter value can be different, and the serialization information will be needed.
In some languages, like dotnet, Std Uri Template could have access to this, but in others it's going to be sitting in a method.
Thoughts?

[andreaTP]

Now on the phone, but, in general I agree.
The information about the string substitution to be done (I.e. EnumMember) is not known to std-uritemplate or it will very much differ across languages.
I think that doing the conversion in the kiota abstractions is the right fix here.

Just to mention, in general I would not be against enum specific handling in std-uritemplate (e.g. like we do for date formats) but, in this case, I think that the most maintainable solution is in abstractions.

[andreaTP]

Opened std-uritemplate/std-uritemplate#91 to showcase how the enum support may look like in std-uritemplate (implemented it in C# and Java ATM).
But this is not going to fully resolve this issue as far as I understand it, and some work should be done in abstractions.

[baywet]

I was able to implement a fix for dotnet. I'll start looking at other languages on how it could be implemented as well.
microsoft/kiota-dotnet#148