Mapping query parameters between two REST API

Question

I would like to use Rest Client to query this endpoint: https://landregistry.data.gov.uk/data/ppi/transaction-record.json . If you access the base URI https://landregistry.data.gov.uk/data/ppi/transaction-record , you can see that the endpoint can take several query parameters. For instance, this is a valid url: https://landregistry.data.gov.uk/data/ppi/transaction-record.json?propertyAddress.postcode=M40%200JE

Since I am sure this is not a new use case, I would like to know what is the best approach to create a "mapping" between the endpoint I am going to expose and the query parameters I can use to create the URI to be invoked?

In other words, taking the example above, my service would expose something like:

localhost:8080/transactions?postcode=M400JE

which will invoke:

https://landregistry.data.gov.uk/data/ppi/transaction-record.json?propertyAddress.postcode=M40%200JE

So, postcode should be translated as propertyAddress.postcode. The same with another 20 potential query parameters.

Answer 1

As far as I know, there isn't anything automatic you can do.

Your endpoint would be:

@Path("/transaction")
public class GreetingResource {

    @Inject
    LandRegistryClient client;

    @GET
    @Produces(MediaType.APPLICATION_JSON)
    public SomeType transaction(@QueryParam("postcode") String postcode) {
        return client.transactionRecord(postcode);
    }

}

and the REST Client would be:

@Path("/data/ppi")
@RegisterRestClient
public interface CountriesService {

    @GET
    @Path("transaction-record.json")
    @Produces(MediaType.APPLICATION_JSON)
    SomeType transactionRecord(@QueryParam("propertyAddress.postcode") String postcode);


}