Question

我是Golang的新手，我正在尝试使用Micro框架和Protobuf框架在Golang中编写家庭自动化框架。

我目前正在努力实现一个简单的注册表类型服务。

我遇到的问题的一个例子是我有以下内容，我希望能够获得设备列表，前提是客户端向http://localhost:8080/view/devices发送GET请求

我有以下protobuf定义：

syntax = "proto3";

service DRegistry {
    rpc View(ViewRequest) returns (DeviceRegistry) {}
} 

message DeviceRegistry {
    repeated Device devices = 1;
}

message ViewRequest {
    string Alias = 1;
}

message Device {
    string Alias = 1;
    string HWAddress = 2;
    string WakeUpMethod = 3;
    repeated string BoundServices = 4;
}

然后在我的服务定义中，我有以下内容：

package main

import (
    "log"

    micro "github.com/micro/go-micro"
    proto "github.com/srizzling/gotham/proto/device"

    "golang.org/x/net/context"
)

// DRegistry stands for Device Registry and is how devices register to Gotham.
type DRegistry struct{}

var devices map[string]proto.Device

func (g *DRegistry) View(ctx context.Context, req *proto.ViewRequest, rsp *proto.DeviceRegistry) error {
    filter := req.Alias
devices, err := filterDevices(filter)
rsp.Devices = devices
}

func filterDevices(filter string) (*[]proto.Device, error) {
    // Currently only supports listing a single service for now
    // TODO: expand filter to be more consise
    filteredDevices := make([]proto.Device, 0, len(devices))
    for _, e := range devices {
        for _, f := range e.BoundServices {
            if f == filter {
                filteredDevices = append(filteredDevices, e)
            }
        }
    }
    return &filteredDevices, nil
}

func main() {
    service := micro.NewService(
        micro.Name("DRegistry"),
    )
    proto.RegisterDRegistryHandler(service.Server(), new(DRegistry))

    if err := service.Run(); err != nil {
        log.Fatal(err)
    }
}

我遇到的问题是我的IDE（Visual Studio Code）正在使我cannot use devices (type *[]device.Device) as type []*device.Device in assignment感到困惑。

TLDR：如何将proto.Devices的集合分配给proto.DeviceRegistry？

Answer 1

func filterDevices(filter string) ([]*proto.Device, error) {
    // Currently only supports listing a single service for now
    // TODO: expand filter to be more consise
    filteredDevices := make([]*proto.Device, 0, len(devices))
    for _, e := range devices {
        for _, f := range e.BoundServices {
            if f == filter {
                filteredDevices = append(filteredDevices, &e)
            }
        }
    }
    return filteredDevices, nil
}

是指针切片（[] *）和指向切片（* []）的指针之间的差异。你正在返回一个指向切片的指针，而你想要的是一片指针。我们可以通过以下方式解决这个问题：

更新filterDevices签名以返回指示片
更新您的make电话以制作一些指针
在你的通话中取e的地址追加（我们想要一些指向设备的指针）
不返回切片的地址

ProtoBuf的Golang解析

1 个答案: