go - 我如何调试我的 Golang API 代码来告诉我哪里出了问题？

Question

我有这个模块，它使用 Google Cloud API 检索特定项目的所有正在运行的虚拟机实例的列表。我是 Go 的新手，并按照介绍教程来帮助我。我仍在尝试调试我的代码，但运气不好。

问题是我能够与 Google Cloud API 通信并通过身份验证，但这就是我所能通过的一切

compute.go模块:

compute.go 能够与谷歌云服务器通信并通过身份验证(我没有收到身份验证错误)

// Copyright 2021 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package compute

// [START compute_instances_list_all]
import (
    "context"
    "fmt"
    "io"

    compute "cloud.google.com/go/compute/apiv1"
    "google.golang.org/api/iterator"
    computepb "google.golang.org/genproto/googleapis/cloud/compute/v1"
    "google.golang.org/protobuf/proto"
)

// listAllInstances prints all instances present in a project, grouped by their zone.
func ListAllInstances(w io.Writer, projectID string) error {
    // projectID := "your_project_id"
    ctx := context.Background()
    instancesClient, err := compute.NewInstancesRESTClient(ctx)
    // instancesClient, err := compute.NewInstancesRESTClient(ctx, option.WithCredentialsFile(`C:\path\to\jsonkey.json`))

    if err != nil {
        return fmt.Errorf("NewInstancesRESTClient: %v", err)
    }
    defer instancesClient.Close()

    // Use the `MaxResults` parameter to limit the number of results that the API returns per response page.
    req := &computepb.AggregatedListInstancesRequest{
        Project:    projectID,
        MaxResults: proto.Uint32(6),
    }

    it := instancesClient.AggregatedList(ctx, req)
    fmt.Fprintf(w, "Instances found:\n")
    // Despite using the `MaxResults` parameter, you don't need to handle the pagination
    // yourself. The returned iterator object handles pagination
    // automatically, returning separated pages as you iterate over the results.
    for {
        pair, err := it.Next()
        if err == iterator.Done {
            break
        }
        if err != nil {
            return err
        }
        instances := pair.Value.Instances
        if len(instances) > 0 {
            fmt.Fprintf(w, "%s\n", pair.Key)
            for _, instance := range instances {
                fmt.Fprintf(w, "- %s %s\n", instance.GetName(), instance.GetMachineType())
            }
        }
    }

    return nil
}

// [END compute_instances_list_all]

但是问题是当我运行调用 ListAllInstances 的主函数时, 它返回一个 <nil> .不让我知道哪里出了问题。

我运行的调用者 api.go 模块 go run . :

package main

import (
    "fmt"

    "example.com/compute"

    "bytes"
)

func main() {
    buf := new(bytes.Buffer)

    // Get a message and print it.
    respone := compute.ListAllInstances(buf, "project-unique-id")
    fmt.Println(respone)
}

我还能如何进一步调试它以找出我的代码有什么问题？

Answer 1

您没有打印 buf。你的函数返回一个类型为error的对象，它是nil(没有错误!)，实际输出被写入buf。

打印出来:

func main() {
    buf := new(bytes.Buffer)

    // Get a message and print it.
    err := compute.ListAllInstances(buf, "project-unique-id")
    if err != nil {
        panic(err)
    }
    fmt.Println(buf.String())  // <======= Print buf contents!
}

或者只使用os.Stdout:

func main() {

    err := compute.ListAllInstances(os.Stdout, "project-unique-id")

    if err != nil {
        panic(err)
    }

}

---

要回答有关调试的问题，请尝试将 VSCode 与 Go extension 结合使用，您可以在其中运行调试器、设置断点并逐行执行代码，观察变量如何变化。

另见 Debug Go programs in VS Code .