在Go中如何返回前端 字段名称/数量都不确定的json数据?
之前用Go写web服务,返回给前端的json格式的接口,有哪些要返回的字段都是明确的。都是预先定义一个结构体,json.Marshal一下即可~
但当有的场景,要返回哪些字段不确定时,就无法使用struct的方式。 还可以用map
package main
import (
"encoding/json"
"fmt"
)
func main() {
Map2Json()
}
func Map2Json() {
mapInstance := make(map[string]interface{})
mapInstance["Name"] = "cs"
mapInstance["Age"] = 28
mapInstance["Address"] = "杭州"
relation := make(map[string]interface{})
relation["father"] = "cuixxxxxxx"
relation["mother"] = "yinxxxxx"
relation["wife"] = "pengxx"
mapInstance["Relation"] = relation
pet := make(map[string]interface{})
pet["one"] = "弥弥懵"
pet["two"] = "黄橙橙"
pet["three"] = "呆呆"
pet["four"] = "皮瓜瓜"
pet["five"] = "斑斑"
mapInstance["Cat"] = pet
jsonStr, err := json.Marshal(mapInstance)
fmt.Println("err is:", err)
fmt.Println("jsonStr is:", string(jsonStr))
}
输出为:
err is: <nil>
jsonStr is: {"Address":"杭州","Age":28,"Cat":{"five":"斑斑","four":"皮瓜瓜","one":"弥弥懵","three":"呆呆","two":"黄橙橙"},"Name":"cs","Relation":{"father":"cuixxxxxxx","mother":"yinxxxxx","wife":"pengxx"}}
在proto中如何定义这样的返回值?
如果使用proto来定义接口,如何定义不确定字段名称和数量的返回值?
即上面的 jsonStr,如何定义才能返回给前端?
尝试使用过Any[1],发现不行(Any的“风评”很不好,介绍时一般和one of出现在一起)
几经探求[2],发现这种情况该用Struct[3](或说Value)类型
[Is "google/protobuf/struct.proto" the best way to send dynamic JSON over GRPC?](https://stackoverflow.com/questions/52966444/is-google-protobuf-struct-proto-the-best-way-to-send-dynamic-json-over-grpc "Is "google/protobuf/struct.proto" the best way to send dynamic JSON over GRPC?")
xxxx.proto:
syntax = "proto3";
package demo;
import "validate/validate.proto";
import "google/api/annotations.proto";
import "google/protobuf/timestamp.proto";
//import "google/protobuf/any.proto";
import "google/protobuf/struct.proto";
rpc Getxxxxx(GetxxxxxReq) returns (GetxxxxxResp) {
option (google.api.http) = {
get:"/api/v1/xxxx/xxxx/xxxxxx"
};
}
message GetxxxxxResp {
google.protobuf.Value data = 1;
}
message GetxxxxxReq {
// 用户名
string user_name = 1
[(validate.rules).string.max_len = 100, (validate.rules).string.min_len = 1];
// 创建时间
google.protobuf.Timestamp create_time = 2;
}
xxxx.go 大致代码如下:
var rs xxxxx
mapInstance["default"] = mapDefault
jsonByteSli, err := json.Marshal(mapInstance)
v := &structpb.Value{}
err = protojson.Unmarshal(jsonByteSli, v)
rs.Data = v
return &rs, nil
struct.proto源码: protobuf/src/google/protobuf/struct.proto[4]
[转]Protobuf3 语法指南[5]
参考资料
Any: https://developers.google.com/protocol-buffers/docs/reference/google.protobuf#google.protobuf.Any
[2]探求: https://github.com/cuishuang/secret/tree/master/tech/proto
[3]Struct: https://developers.google.com/protocol-buffers/docs/reference/google.protobuf#struct
[4]protobuf/src/google/protobuf/struct.proto: https://github.com/protocolbuffers/protobuf/blob/main/src/google/protobuf/struct.proto
[5][转]Protobuf3 语法指南: https://colobu.com/2017/03/16/Protobuf3-language-guide/
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