按照 go 示例，我使用以下代码将文件上传到 google 存储桶：

func uploadFile(bucket string, uploadFilePath string, destFilePath string) error {
    os.Setenv("GOOGLE_APPLICATION_CREDENTIALS", "./credential.json")
    ctx := context.Background()
    client, err := storage.NewClient(ctx)
    if err != nil {
        return fmt.Errorf("storage.NewClient: %v", err)
    }
    defer client.Close()

    // Open local file.
    f, err := os.Open(uploadFilePath)
    if err != nil {
        return fmt.Errorf("os.Open: %v", err)
    }
    defer f.Close()

    ctx, cancel := context.WithTimeout(ctx, time.Second*50)
    defer cancel()
    o := client.Bucket(bucket).Object(destFilePath)
    o = o.If(storage.Conditions{DoesNotExist: true})
    
    // Upload an object with storage.Writer.
    wc := o.NewWriter(ctx)
    if _, err = io.Copy(wc, f); err != nil {
        return fmt.Errorf("io.Copy: %v", err)
    }
    if err := wc.Close(); err != nil {
        return fmt.Errorf("Writer.Close: %v", err)
    }
    return nil
}

func main() {
    bucket := "g1-mybucket-001"
    targetFilePath := "./somefile.txt"
    destFilePath := "it_poc_test_folder/somefile.txt"
    err := uploadFile(bucket, targetFilePath, destFilePath)
    if err != nil {
        fmt.Println(fmt.Errorf("Error uplolading file: %v", err))
    } else {
        fmt.Printf("%s uploaded to %s.n", targetFilePath, destFilePath)
    }
}

现在我计划将其包装起来，创建一个用于文件上传的 rest api。然后我意识到该代码仅用于上传本地文件。如何包装它以便文件直接进入存储桶，而不需要先将其上传到服务器？

正确答案

有很多文件上传示例，要点是：

func uploadfile(w http.responsewriter, r *http.request) {

    // ... 
    r.parsemultipartform(10 << 20)
    f, handler, err := r.formfile("myfile")
    if err != nil {
        // handle err
    }
    defer f.close()
    // ...
}

因此，只需将文件上传的 f 主体传递到您的云上传逻辑，就好像它是本地文件一样：

// same code - different `f` source

// Upload an object with storage.Writer.
wc := o.NewWriter(ctx)
if _, err = io.Copy(wc, f); err != nil {
    return fmt.Errorf("io.Copy: %v", err)
}