将ptypes/struct值转换为BSON [英] Go converting ptypes/struct Value to BSON

问题描述

两项服务:

• 服务器-用于将博客文章写入MongoDB
• 客户端-将请求发送到第一个服务

• Server - for writing blog posts to MongoDB
• Client - sends request to the first service

博客文章的title类型为string，而content是动态类型-可以是任何JSON值.

The blog post has title of type string, and content which is a dynamic type - can be any JSON value.

syntax = "proto3";

package blog;

option go_package = "blogpb";

import "google/protobuf/struct.proto";

message Blog {
  string id = 1;
  string title = 2;
  google.protobuf.Value content = 3;
}

message CreateBlogRequest {
  Blog blog = 1;
}

message CreateBlogResponse {
  Blog blog = 1;
}

service BlogService {
  rpc CreateBlog (CreateBlogRequest) returns (CreateBlogResponse);
}

让我们从protobuf消息开始，它满足了要求-title的string和content的任何JSON值.

Let's start with protobuf message, which meats requirements - string for title and any JSON value for content.

package main

import (...)

func main() {
    cc, _ := grpc.Dial("localhost:50051", grpc.WithInsecure())
    defer cc.Close()
    c := blogpb.NewBlogServiceClient(cc)

    var blog blogpb.Blog

    json.Unmarshal([]byte(`{"title": "First example", "content": "string"}`), &blog)
    c.CreateBlog(context.Background(), &blogpb.CreateBlogRequest{Blog: &blog})

    json.Unmarshal([]byte(`{"title": "Second example", "content": {"foo": "bar"}}`), &blog)
    c.CreateBlog(context.Background(), &blogpb.CreateBlogRequest{Blog: &blog})
}

客户端向服务器发送两个请求-一个请求使用string类型的content，另一个请求使用object.这里没有错误.

The client sends two requests to the server - one with content having string type, and other with the object. No errors here.

package main

import (...)

var collection *mongo.Collection

type server struct {
}

type blogItem struct {
    ID      primitive.ObjectID `bson:"_id,omitempty"`
    Title   string             `bson:"title"`
    Content *_struct.Value     `bson:"content"`
}

func (*server) CreateBlog(ctx context.Context, req *blogpb.CreateBlogRequest) (*blogpb.CreateBlogResponse, error) {
    blog := req.GetBlog()

    data := blogItem{
        Title:   blog.GetTitle(),
        Content: blog.GetContent(),
    }

    // TODO: convert "data" or "data.Content" to something that could be BSON encoded..

    res, err := collection.InsertOne(context.Background(), data)
    if err != nil {
        log.Fatal(err)
    }
    oid, _ := res.InsertedID.(primitive.ObjectID)

    return &blogpb.CreateBlogResponse{
        Blog: &blogpb.Blog{
            Id:      oid.Hex(),
            Title:   blog.GetTitle(),
            Content: blog.GetContent(),
        },
    }, nil

}

func main() {
    client, _ := mongo.NewClient(options.Client().ApplyURI("mongodb://localhost:27017"))
    client.Connect(context.TODO())
    collection = client.Database("mydb").Collection("blog")
    lis, _ := net.Listen("tcp", "0.0.0.0:50051")
    s := grpc.NewServer([]grpc.ServerOption{}...)
    blogpb.RegisterBlogServiceServer(s, &server{})
    reflection.Register(s)
    go func() { s.Serve(lis) }()
    ch := make(chan os.Signal, 1)
    signal.Notify(ch, os.Interrupt)
    <-ch
    client.Disconnect(context.TODO())
    lis.Close()
    s.Stop()
}

然后我得到:

无法将类型main.blogItem转换为BSON文档:无编码器 找到structpb.isValue_Kind

cannot transform type main.blogItem to a BSON Document: no encoder found for structpb.isValue_Kind

我期望什么?要查看MongoDB中内容的确切价值，请执行以下操作:

What do I expect? To see the exact value of content in MongoDB, something like this:

{ "_id" : ObjectId("5e5f6f75d2679d058eb9ef79"), "title" : "Second example", "content": "string" }
{ "_id" : ObjectId("5e5f6f75d2679d058eb9ef78"), "title" : "First example", "content": { "foo": "bar" } }

我想我需要在添加TODO: ...的行中转换data.Content ...

I guess I need to transform data.Content in the line where I added TODO:...

如果可以的话，我可以使用此示例创建github存储库.

I can create github repo with this example if that could help.

推荐答案

因此，如@ nguyenhoai890在评论中所建议，我设法使用jsonpb lib对其进行了修复-首先MarshalToString将其从structpb转换为，然后按json.Unmarshal从BSON支持的string(json)转换为interface{}.另外，我还必须修复一个Client，以正确地将其从字符串解封为protobuf.

So as suggested by @nguyenhoai890 in the comment I managed to fix it using jsonpb lib - first MarshalToString to covert from structpb to string(json) and then json.Unmarshal to convert from string(json) to interface{} which is supported by BSON. Also I had to fix a Client to correctly unmarshal from string to protobuf.

func main() {
    cc, _ := grpc.Dial("localhost:50051", grpc.WithInsecure())
    defer cc.Close()
    c := blogpb.NewBlogServiceClient(cc)

    var blog blogpb.Blog
    jsonpb.UnmarshalString(`{"title": "Second example", "content": {"foo": "bar"}}`, &blog)
    c.CreateBlog(context.Background(), &blogpb.CreateBlogRequest{Blog: &blog})

    jsonpb.UnmarshalString(`{"title": "Second example", "content": "stirngas"}`, &blog)
    c.CreateBlog(context.Background(), &blogpb.CreateBlogRequest{Blog: &blog})
}

服务器

type blogItem struct {
    ID      primitive.ObjectID `bson:"_id,omitempty"`
    Title   string             `bson:"title"`
    Content interface{}        `bson:"content"`
}

func (*server) CreateBlog(ctx context.Context, req *blogpb.CreateBlogRequest) (*blogpb.CreateBlogResponse, error) {
    blog := req.GetBlog()

    contentString, err := new(jsonpb.Marshaler).MarshalToString(blog.GetContent())
    if err != nil {
        log.Fatal(err)
    }

    var contentInterface interface{}
    json.Unmarshal([]byte(contentString), &contentInterface)

    data := blogItem{
        Title:   blog.GetTitle(),
        Content: contentInterface,
    }

    res, err := collection.InsertOne(context.Background(), data)
    if err != nil {
        log.Fatal(err)
    }
    oid, _ := res.InsertedID.(primitive.ObjectID)

    return &blogpb.CreateBlogResponse{
        Blog: &blogpb.Blog{
            Id:      oid.Hex(),
            Title:   blog.GetTitle(),
            Content: blog.GetContent(),
        },
    }, nil

}

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