Query string parameters are not correctly removed from downstream template

[webley]

Expected Behavior

I want to be able to map a query parameter on my gateway API to a query parameter with a different name on my downstream API.

{
  "Routes": [
    {
      "DownstreamPathTemplate": "/persons?personId={userId}",
      "UpstreamPathTemplate": "/users?userId={userId}"
    } 
  ]
}

When calling /users?userId=webley, I would expect the downstream call to be /persons?personId=webley

Actual Behavior

The downstream route generated is /persons?userId=webley&personId=webley

Steps to Reproduce the Problem

1. Create a re-route with query strings in both the upstream and downstream templates
2. Call into the upstream endpoint
3. The unwanted query parameter will remain on the downstream request

In DownstreamUrlCreatorMiddleware.cs, the method RemoveQueryStringParametersThatHaveBeenUsedInTemplate(context) seems to be called if the downstream path does not contain a query string. I have tested that this works as expected. However, if the downstream path contains a query string, unused params from the upstream template are never removed. I think they probably should be.

Specifications

• Version: 13.8.0-alpha0006 (and 13.5.2)
• Platform: Win 10

[wast]

When this gets fixed, it will be Major change because it could break apps that used this as a feature.

[raman-m]

@wast commented on Jan 3, 2020
When this gets fixed, it will be Major change because it could break apps that used this as a feature.

Oh, really? The feature (fix) will forward new query parameter and remove old one.
Developer must double check upstream & downstream path as an author of a route.
We can say about that in Release Notes. Sounds good?