Go App Engine 写入 Google Datastore 挂起

Question

我正在使用 Go 编写一个简单的 App Engine 程序。我需要将一些数据写入 Google DataStore。当我尝试将数据放入存储时，程序一直挂起。这整个星​​期都困扰着我。

在某个时候，我设法将数据写入 DataStore，直到我发现如何在 Cloud Console 中查看上传的数据后才意识到这一点。从那以后我已经对代码进行了很多更改，现在我不能再写任何数据了。它每次都挂起。

日志显示没有任何帮助。仅通知该过程已超时。没有从程序写入的日志，仅从系统写入。

由于超出了请求期限，进程终止。 （错误代码 123）

我尝试使用this link 更改导入语句，但编译失败，所以我返回this link，编译没有问题。

我考虑到我的开发环境可能以某种方式严重错误配置（也许是毁容？），所以我去了一台干净的机器并仔细进行了新安装。它仍然挂起。

我的 app.yaml 文件：

runtime: go
    api_version: go1

handlers:
    - url: /.*
      script: _go_app

我添加的一个 index.yaml 文件：

indexes:

    - kind: Bacon
        properties:
    - name: YCode
        direction: asc
    - name: URL
    - name: Owner
    - name: Location

这是我的代码：

package main

    import (
        "fmt"
        "log"
        "net/http"
        "google.golang.org/appengine/datastore"
        "google.golang.org/appengine" 
    )

     type Bacon struct {
        YCode string
        URL string
        Owner string
        Location string
    } 

    func main() {
        http.HandleFunc("/", indexHandler)
        appengine.Main() 
    }

    func indexHandler(w http.ResponseWriter, r *http.Request) {

        ctx := appengine.NewContext(r)
        projectID := "fake-for-discussion-thread-787987"

        client, err := datastore.NewClient(ctx, projectID)
        if err != nil {
            log.Fatalf("Failed to create client: %v", err)
            return
        } 

        kind := "Bacon"
        name := "3"
        baconKey := datastore.NameKey(kind, name, nil)

        //Make bacon
        bacon := Bacon{
            YCode: "1",
            URL: "http://www.safeway.com",
            Owner: "Bob",
            Location: "Deli",
        }

        // I've confirmed that this is where it hangs every time.  
        // It doesn't even capture my silly fatal log entry. 
        // It just times out and finally sends a 500 Server Error.
        if _, err := client.Put(ctx, baconKey, &bacon); err != nil {
            log.Fatalf("Failed to save my Bacon: %v", err)
        }

        client.Close()

    }

非常感谢您提供的任何帮助！

Answer 1

好的！所以这真的把我逼到了墙角，但今天早上我设法打破了它。我很难找到在线文档，我想确保我把我的（现在工作的）代码放进去，这样其他人就可以免于痛苦。

值得注意的是，如果您要部署到 App Engine，我开始怀疑 Go 文档/示例可能会让您走错路。 App Engine 不喜欢某些核心 Go 库等。在部署到 App Engine 时，这可能会变得非常混乱。

另外请注意，我从最初的问题中学到了很多经验教训。我正在输入此条目，以便我可以正确发布我的固定 App Engine 特定代码。

    //Modified to work on App Engine. May not work right locally, etc.

    package main

    import (
        "fmt"
        "log"
        "net/http"
        "google.golang.org/appengine/datastore"
        "google.golang.org/appengine" 
    )

     type Bacon struct {
        YCode string
        URL string
        Owner string
        Location string
    } 

    func main() {
        http.HandleFunc("/", indexHandler)
        appengine.Main() 
    }

    func indexHandler(w http.ResponseWriter, r *http.Request) {

        //This gives a context that makes App Engine happy      
        ctx := appengine.NewContext(r)

        //NOT NEEDED (Apparently, App Engine knows who you are. Creepy.)    
        //projectID := "fake-for-discussion-thread-787987" 

        //NOT NEEDED (And may actually cause you great woe!)
        //client, err := datastore.NewClient(ctx, projectID)
        //if err != nil {
        //  log.Fatalf("Failed to create client: %v", err)
        //  return
        //} 

        //Turns out that these aren't needed, either. 
        //kind := "Bacon"
        //name := "3"

        //Note the changes from my original code, including the
        //change from NameKey to NewIncompleteKey and the
        //hard-coding of Bacon in the arguments. Alternatively, you might
        //use a variable, depending on your needs. I just need bacon.
        //This causes the entity you create in Google DataStore 
        //to have a "Kind" of "Bacon"
        baconKey := datastore.NewIncompleteKey(ctx, "Bacon", nil)

        //Make bacon
        bacon := Bacon{
            YCode: "1",
            URL: "http://www.safeway.com",
            Owner: "Bob",
            Location: "Deli",
        }

        // Note changes here. No more client, just a call to datastore.Put.
        // Now it works!  One caveat: I'm still trying to figure out why it writes 
        // my data twice. But, hey!  At least it's writing!
        if _, err := datastore.Put(ctx, baconKey, &bacon); err != nil {
            log.Fatalf("Failed to save my Bacon: %v", err)
        }

        //No client, so no need to close.
        //client.Close()

    }

干杯！