Spring Cloud Gateway - how to pass dynamic YAML filter arguments

Question

I've got a Spring Cloud Gateway app configured with YML. I want to create a custom filter that basically combines the responses of two endpoints into one brand new object which is then returned to the client. However, I will have many cases where I want to combine such API calls, and in order to avoid creating a brand new route in my YML config for each of them, I want to somehow dynamically pass the filter arguments in such a way that they are set by the initial request made to this route. Here's how the configuration looks:

        - id: claims-composite-call-test-1
          uri: http://1.2.3.4:1234
          predicates:
            - Path=/claims/**
          filters:
            - name: CompositeClaimAndRequestFilter
              args:
                uris: http://1.2.3.4:1234/claims/v1/2000, http://1.2.3.4:1234/claims/v1/2000/requests/1

Basically what the filter does is when I hit the above route (regardless of what path I use), it makes two separate GET requests towards the two URIs specified in the filter argument uris. It then combines the two responses of those endpoints into a brand new object and returns it to the client.

However, In this case I have hardcoded the IDs of the two objects towards which I'm making the request - it's the 2000 part of both arguments. So now if I want to make the same composite call but towards object with ID 3000, I need to create a brand new route in my configuration, and that's a major inconvenience for obvious reasons.

Is there a way to define the configuration such that it dynamically takes the ID of the object via the initial request made and plugs it into the filter arguments before the filter kicks in?

For example, I make a request towards http://1.2.3.4:1234/claims/composite/5000, and then the configuration would look something like:

        - id: claims-composite-call-test-1
          uri: http://1.2.3.4:1234
          predicates:
            - Path='/claims/composite/' + objectId
          filters:
            - name: CompositeClaimAndRequestFilter
              args:
                uris: 'http://1.2.3.4:1234/claims/v1/' + objectId, 'http://1.2.3.4:1234/claims/v1/' + objectId + '/requests/1'

So the resulting args would be http://1.2.3.4:1234/claims/v1/5000 and http://1.2.3.4:1234/claims/v1/5000/requests/1 respectively.

Is this even possible when the gateway is configured via YAML? I know I can pass the ID as a header or a cookie, but I prefer not having to modify the default initial request. Thanks in advance!

Answer 1

Aggregate with the paste function, roughly:

aggregate(df$name, by=list(df$address), FUN=paste)