fixup! fix(admin): reject AdminAPI call with empty tags

PR Review fixes - improve error message: remove info about empty string

kong/api/endpoints.lua

@@ -156,8 +156,8 @@ local function extract_options(db, args, schema, context)
     end
 
     if schema.fields.tags and args.tags ~= nil and context == "page" then
-      if args.tags == null then
-        local error_message = "tags cannot be null (or empty string)"
+      if args.tags == null or #args.tags == 0 then
+        local error_message = "cannot be null"
         return nil, error_message, db[schema.name].errors:invalid_options({tags = error_message})
       end
 

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

@@ -290,7 +290,7 @@ describe("Admin API (#" .. strategy .. "): ", function()
         })
         res = assert.res_status(400, res)
         local json = cjson.decode(res)
-        assert.same("invalid option (tags: tags cannot be null (or empty string))", json.message)
+        assert.same("invalid option (tags: cannot be null)", json.message)
       end)
     end)
     it("returns 405 on invalid method", function()

spec/02-integration/04-admin_api/07-upstreams_routes_spec.lua

@@ -645,7 +645,7 @@ describe("Admin API: #" .. strategy, function()
         })
         res = assert.res_status(400, res)
         local json = cjson.decode(res)
-        assert.same("invalid option (tags: tags cannot be null (or empty string))", json.message)
+        assert.same("invalid option (tags: cannot be null)", json.message)
       end)
 
       describe("empty results", function()

spec/02-integration/04-admin_api/14-tags_spec.lua

@@ -80,7 +80,17 @@ describe("Admin API - tags", function()
         })
         local body = assert.res_status(400, res)
         local json = cjson.decode(body)
-        assert.same("invalid option (tags: tags cannot be null (or empty string))", json.message)
+        assert.same("invalid option (tags: cannot be null)", json.message)
+      end)
+
+      it("filter by empty string tag", function()
+        local res = assert(client:send {
+          method = "GET",
+          path = "/consumers?tags=''"
+        })
+        local body = assert.res_status(200, res)
+        local json = cjson.decode(body)
+        assert.equals(0, #json.data)
       end)
 
       it("filter by multiple tags with AND", function()