A client/server helper wrapper for endpoints in Go.

go/src/infra/gae/epservice/example/service_add.go

+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package example
+
+import (
+        "golang.org/x/net/context"
+        "infra/gae/libs/wrapper"
+        "infra/gae/libs/wrapper/gae"
+        "infra/gae/libs/wrapper/gae/commonErrors"
+
+        "github.com/GoogleCloudPlatform/go-endpoints/endpoints"
+)
+
+// AddReq describes the input parameters to the 'Add' RPC. Name is required,
+// which makes it show up in the REST path, and Delta will be encoded in the
+// request body as JSON.
+type AddReq struct {
+        Name string `endpoints:"required"`
+
+        Delta int64 `json:",string"`
+}
+
+// AddRsp describes the return value from the 'Add' RPC. Prev is the previous
+// value, and Cur is the post-increment value.
+type AddRsp struct {
+        Prev int64 `json:",string"`
+        Cur  int64 `json:",string"`
+}
+
+// Add adds a value to the current counter, and returns the old+new values. It
+// may cause a counter to come into existance.
+func (Example) Add(c endpoints.Context, r *AddReq) (rsp *AddRsp, err error) {
+        rsp = &AddRsp{}
+
+        ds := wrapper.GetDS(gae.Use(context.Background(), c))
+        err = ds.RunInTransaction(func(context.Context) error {
+                ctr := &Counter{ID: r.Name}
+                if err := ds.Get(ctr); err != nil && err != commonErrors.ErrNoSuchEntityDS {
+                        return err
+                }
+                rsp.Prev = ctr.Val
+                ctr.Val += r.Delta
+                rsp.Cur = ctr.Val
+                _, err := ds.Put(ctr)
+                return err
+        }, nil)
+        return
+}
+
+func init() {
+        mi["Add"] = &endpoints.MethodInfo{
+                Path: "counter/{Name}",
+                Desc: "Add an an amount to a particular counter",
+        }
+}