fix(api) consumers endpoint filtering by custom id

This issue was reported by @JoarSvensson on issue #4402.

kong/api/endpoints.lua

@@ -234,10 +234,10 @@ local function query_entity(context, self, db, schema, method)
   end
 
   if is_update then
-    return dao[method or context](dao, key, args, opts)
+    return dao[method or context](dao, method and key.id or key, args, opts)
   end
 
-  return dao[method or context](dao, key, opts)
+  return dao[method or context](dao, method and key.id or key, opts)
 end
 
 

spec/02-integration/04-admin_api/03-consumers_routes_spec.lua

@@ -255,6 +255,17 @@ describe("Admin API (#" .. strategy .. "): ", function()
         local body = assert.res_status(200, res)
         local json = cjson.decode(body)
 
+        assert.equal(1, #json.data)
+        assert.same(c, json.data[1])
+      end)
+      it("allows filtering by uuid-like custom_id", function()
+        local custom_id = utils.uuid()
+        local c = bp.consumers:insert({ custom_id = custom_id }, { nulls = true })
+
+        local res = client:get("/consumers?custom_id=" .. custom_id)
+        local body = assert.res_status(200, res)
+        local json = cjson.decode(body)
+
         assert.equal(1, #json.data)
         assert.same(c, json.data[1])
       end)