英文:
Upload Json Array from GAE to Cloud Storage in GO
问题
我正在尝试使用以下代码将由App Engine应用程序发布的JSON数组上传到Google Cloud Storage：
saveData: function saveData() {
var _this = this,
save = this.shadowRoot.querySelector('#save-data'),
subData = JSON.stringify(_this.app.userSession);
save.url="url";
save.body = subData;
save.go();
}
在上述代码中，使用go函数处理发布的消息。使用下面的代码，我能够在云存储存储桶中创建一个以用户ID命名的文件夹。我希望能够将整个JSON数组（即代码中的变量f）复制到该文件夹中。我尝试使用io.Copy(wc, f)，但是它给出了以下错误：
无法将content（类型为userData）作为io.Reader类型的参数传递给io.Copy：
userData未实现io.Reader（缺少Read方法）
显然，我做错了什么，但我对Go语言还很陌生，完全被困住了。有人可以帮助我吗？
package expt
import (
"bytes"
"encoding/json"
"io/ioutil"
"log"
"net/http"
"golang.org/x/net/context"
"golang.org/x/oauth2"
"golang.org/x/oauth2/google"
"google.golang.org/appengine"
"google.golang.org/appengine/file"
"google.golang.org/appengine/urlfetch"
"google.golang.org/cloud"
"google.golang.org/cloud/storage"
)
var bucket = "expt"
func init() {
http.HandleFunc("/", handleStatic)
http.HandleFunc("/save", saveJson)
}
func handleStatic(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Cache-Control", "no-cache")
http.ServeFile(w, r, "static/"+r.URL.Path)
}
type Result map[string]interface{}
type userData struct {
id string
age string
gender string
}
func testA(r *http.Request) userData {
defer r.Body.Close()
body, err := ioutil.ReadAll(r.Body)
var userDataCurr userData
if err != nil {
log.Printf("Couldn't read request body: %s", err)
} else {
var f Result
err := json.Unmarshal(body, &f)
if err != nil {
log.Println("Error: %s", err)
} else {
user := f["user"].(map[string]interface{})
userDataCurr.id = user["id"].(string)
}
}
return userDataCurr
}
type saveData struct {
c context.Context
r *http.Request
w http.ResponseWriter
ctx context.Context
cleanUp []string
failed bool
}
func (d *saveData) errorf(format string, args ...interface{}) {
d.failed = true
// log.Errorf(d.c, format, args...)
}
func saveJson(w http.ResponseWriter, r *http.Request) {
c := appengine.NewContext(r)
if bucket == "" {
var err error
if bucket, err = file.DefaultBucketName(c); err != nil {
// log.Errorf(c, "failed to get default GCS bucket name: %v", err)
return
}
}
hc := &http.Client{
Transport: &oauth2.Transport{
Source: google.AppEngineTokenSource(c, storage.ScopeFullControl),
Base: &urlfetch.Transport{Context: c},
},
}
ctx := cloud.NewContext(appengine.AppID(c), hc)
d := &saveData{
c: c,
r: r,
w: w,
ctx: ctx,
}
d.createUserFolder()
}
func (d *saveData) createFile(fileName string) {
wc := storage.NewWriter(d.ctx, bucket, fileName)
wc.ContentType = "text/plain"
d.cleanUp = append(d.cleanUp, fileName)
if err := wc.Close(); err != nil {
d.errorf("createFile: unable to close bucket %q, file %q: %v", bucket, fileName, err)
return
}
}
func (d *saveData) createUserFolder() {
var (
content = testA(d.r)
buffer bytes.Buffer
)
buffer.WriteString(content.id)
buffer.WriteString("/")
d.createFile(buffer.String())
}
希望这可以帮助到你！
英文:
I trying to upload to google cloud storage a json array which is posted by an app engine application using the following code:
saveData : function saveData() {
var _this = this,
save = this.shadowRoot.querySelector('#save-data'),
subData = JSON.stringify(_this.app.userSession);
save.url="url";
save.body = subData;
save.go();
}
The posted message is handled in go with the code posted below. With this code I'm able to create a folder on the cloud storage bucket which is named with the user ID. What I would love to do is to copy into the folder the entire json array -i.e. the variable f in the code below. I tried with io.Copy(wc, f) but it gives me the following error:
> cannot use content (type userData) as type io.Reader in argument to
> io.Copy:
> userData does not implement io.Reader (missing Read method)
Obviously I'm doing something wrong, but I'm quite new to go and I'm totally stuck. Can someone help me?
package expt
import (
"bytes"
"encoding/json"
"io/ioutil"
"log"
"net/http"
"golang.org/x/net/context"
"golang.org/x/oauth2"
"golang.org/x/oauth2/google"
"google.golang.org/appengine"
"google.golang.org/appengine/file"
"google.golang.org/appengine/urlfetch"
"google.golang.org/cloud"
"google.golang.org/cloud/storage"
)
var bucket = "expt"
func init() {
http.HandleFunc("/", handleStatic)
http.HandleFunc("/save", saveJson)
}
func handleStatic(w http.ResponseWriter, r *http.Request) {
w.Header().Set("Cache-Control", "no-cache")
http.ServeFile(w, r, "static/"+r.URL.Path)
}
type Result map[string]interface {
}
type userData struct {
id string
age string
gender string
}
func testA(r *http.Request) userData {
defer r.Body.Close()
body, err := ioutil.ReadAll(r.Body)
var userDataCurr userData
if err != nil {
log.Printf("Couldn't read request body: %s", err)
} else {
var f Result
err := json.Unmarshal(body, &f)
if err != nil {
log.Println("Error: %s", err)
} else {
user := f["user"].(map[string]interface{})
userDataCurr.id = user["id"].(string)
}
}
return userDataCurr
}
// saveData struct holds information needed to run the various saving functions.
type saveData struct {
c context.Context
r *http.Request
w http.ResponseWriter
ctx context.Context
// cleanUp is a list of filenames that need cleaning up at the end of the saving.
cleanUp []string
// failed indicates that one or more of the saving steps failed.
failed bool
}
func (d *saveData) errorf(format string, args ...interface{}) {
d.failed = true
// log.Errorf(d.c, format, args...)
}
// testSave is the main saving entry point that calls the GCS operations.
func saveJson(w http.ResponseWriter, r *http.Request) {
c := appengine.NewContext(r)
if bucket == "" {
var err error
if bucket, err = file.DefaultBucketName(c); err != nil {
// log.Errorf(c, "failed to get default GCS bucket name: %v", err)
return
}
}
hc := &http.Client{
Transport: &oauth2.Transport{
Source: google.AppEngineTokenSource(c, storage.ScopeFullControl),
Base: &urlfetch.Transport{Context: c},
},
}
ctx := cloud.NewContext(appengine.AppID(c), hc)
d := &saveData{
c: c,
r: r,
w: w,
ctx: ctx,
}
d.createUserFolder()
}
// createFile creates a file in Google Cloud Storage.
func (d *saveData) createFile(fileName string) {
wc := storage.NewWriter(d.ctx, bucket, fileName)
wc.ContentType = "text/plain"
d.cleanUp = append(d.cleanUp, fileName)
if err := wc.Close(); err != nil {
d.errorf("createFile: unable to close bucket %q, file %q: %v", bucket, fileName, err)
return
}
}
//create files that will be used by listBucket.
func (d *saveData) createUserFolder() {
var (
content = testA(d.r)
buffer bytes.Buffer
)
buffer.WriteString(content.id)
buffer.WriteString("/")
d.createFile(buffer.String())
}
答案1
得分: 0
这段代码非常混乱，但从我所能看到的内容来看，你是想要做以下操作：
func (d *saveData) createFile(fileName string, content userData) {
wc := storage.NewWriter(d.ctx, bucket, fileName)
wc.ContentType = "text/plain"
d.cleanUp = append(d.cleanUp, fileName)
//*** 新代码 *******
io.Copy(wc, content)
//********************
if err := wc.Close(); err != nil {
d.errorf("createFile: unable to close bucket %q, file %q: %v", bucket, fileName, err)
return
}
}
你不能直接将对象写入文件，需要先进行编码。我猜你想要使用 JSON 格式。你可以这样做：
bs, err := json.Marshal(content)
if err != nil {
return err
}
io.Copy(wc, bytes.NewReader(bs))
但更好的做法是使用 json.NewEncoder：
json.NewEncoder(wc).Encode(content)
你的 createUserFolder 也可以简化（不需要使用缓冲区来拼接字符串）：
func (d *saveData) createUserFolder() {
content := testA(d.r)
d.createFile(content.id + "/")
}
我不知道 testA 的含义，但它也可以简化：
type UserData struct {
ID string `json:"id"`
Age string `json:"age"`
Gender string `json:"gender"`
}
func testA(r *http.Request) UserData {
defer r.Body.Close()
var obj struct {
User UserData `json:"user"`
}
err := json.NewDecoder(r.Body).Decode(&obj)
if err != nil {
log.Println("Error: %s", err)
}
return obj.User
}
使用大写字段名，这样 JSON 可以自动进行转换。
可能还有很多重构的工作要做，但也许这些就足够开始了。
<details>
<summary>英文:</summary>
This code is very confusing but from what I can tell are you trying to do this:
func (d *saveData) createFile(fileName string, content userData) {
wc := storage.NewWriter(d.ctx, bucket, fileName)
wc.ContentType = "text/plain"
d.cleanUp = append(d.cleanUp, fileName)
//*** new code *******
io.Copy(wc, content)
//********************
if err := wc.Close(); err != nil {
d.errorf("createFile: unable to close bucket %q, file %q: %v", bucket, fileName, err)
return
}
}
You can't write an object directly to a file, it needs to be encoded first. I'm assuming you want json. You could do it this way:
bs, err := json.Marshal(content)
if err != nil {
return err
}
io.Copy(wc, bytes.NewReader(bs))
But it would be better to use `json.NewEncoder`:
json.NewEncoder(wc).Encode(content)
Your `createUserFolder` can also be simplified (you don't need a buffer to concatenate strings):
func (d *saveData) createUserFolder() {
content := testA(d.r)
d.createFile(content.id + "/")
}
I don't know what `testA` is supposed to mean, but it too can be simplified:
type UserData {
ID string `json:"id"`
Age string `json:"age"`
Gender string `json:"gender"`
}
func testA(r *http.Request) UserData {
defer r.Body.Close()
var obj struct {
User UserData `json:"user"`
}
err := json.NewDecoder(r.Body).Decode(&obj)
if err != nil {
log.Println("Error: %s", err)
}
return obj.User
}
Use uppercase field names so that json can handle the conversion for you.
There's probably a lot more refactoring to be done, but maybe that's enough to get started.
</details>
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