XmlCommentOperationTransformer null reference exception

[reengineeringdevops]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Hi,
After migrating my APIs from .NET 9 to .NET 10, I started receiving the attached exception because parameterDescription.ModelMetadata is null.
Can you investigate ?

Thanks in advance

Reengineering S.r.L

Expected Behavior

No response

Steps To Reproduce

No response

Exceptions (if any)

.NET Version

10.0.0-rc.1.25451.107

Anything else?

No response

[reengineeringdevops]

Hi,
You can find the reproduced bug here:

https://github.com/reengineeringdevops/XmlCommentOperationTransformerBug

Best regards,

Reengineering S.r.L

[martincostello]

Can you replicate the issue without API Versioning? If not, then the issue may be in that library.

[reengineeringdevops]

Can you replicate the issue without API Versioning? If not, then the issue may be in that library.

Hi @martincostello
I just updated the code base removing API versioning. Look like that the bug occurs when a parameter is specified in the URL of an Http attribute, but the corresponding variable is missing from the method signature.

It’s definitely a messy situation, but if this case really needs to be supported, I think a different exception should be raised to inform the developer which method is affected by the issue.

[desjoerd]

That would mean the ModelMetadata is null.

It looks like a problem in NRT annotations on that property as it's specified to be never null.

The solution would be to add a null check and a unit test based on your description.

[desjoerd]

I've created a PR with a unit test for it 😊. @captainsafia please check if this can be backported to .NET 10. I think this is a "semi" common use case where a route parameter is added to the route but isn't used in the controller. For example when using middleware to extract this param and doing validations/authorization on it.