[原文地址](https://bingjian-zhu.github.io/2020/04/23/Go-gRPC%E8%BF%9B%E9%98%B6-proto%E6%95%B0%E6%8D%AE%E9%AA%8C%E8%AF%81%EF%BC%88%E4%B9%9D%EF%BC%89/)
### 前言
上篇介绍了[go-grpc-middleware](https://github.com/grpc-ecosystem/go-grpc-middleware)的`grpc_zap`、`grpc_auth`和`grpc_recovery`使用，本篇将介绍`grpc_validator`，它可以对gRPC数据的输入和输出进行验证。
### 创建proto文件，添加验证规则
这里使用第三方插件[go-proto-validators](https://github.com/mwitkow/go-proto-validators)自动生成验证规则。
`go get github.com/mwitkow/go-proto-validators`
1.新建simple.proto文件
```protobuf
syntax = "proto3";
package proto;
import "github.com/mwitkow/go-proto-validators/validator.proto";
message InnerMessage {
// some_integer can only be in range (1, 100).
int32 some_integer = 1 [(validator.field) = {int_gt: 0, int_lt: 100}];
// some_float can only be in range (0;1).
double some_float = 2 [(validator.field) = {float_gte: 0, float_lte: 1}];
}
message OuterMessage {
// important_string must be a lowercase alpha-numeric of 5 to 30 characters (RE2 syntax).
string important_string = 1 [(validator.field) = {regex: "^[a-z]{2,5}$"}];
// proto3 doesn't have `required`, the `msg_exist` enforces presence of InnerMessage.
InnerMessage inner = 2 [(validator.field) = {msg_exists : true}];
}
service Simple{
rpc Route (InnerMessage) returns (OuterMessage){};
}
```
代码`import "github.com/mwitkow/go-proto-validators/validator.proto"`，文件`validator.proto`需要`import "google/protobuf/descriptor.proto";`包，不然会报错。
`google/protobuf`地址：https://github.com/protocolbuffers/protobuf/blob/master/src/google/protobuf/descriptor.proto。
把`src`文件夹中的`protobuf`目录下载到GOPATH目录下。
2.编译simple.proto文件
`go get github.com/mwitkow/go-proto-validators/protoc-gen-govalidators`
指令编译：`protoc --govalidators_out=. --go_out=plugins=grpc:./ ./simple.proto`
> 或者使用`VSCode-proto3`插件，[第一篇](https://www.cnblogs.com/FireworksEasyCool/p/12669371.html)有介绍。只需要添加`"--govalidators_out=."`即可。
```
// vscode-proto3插件配置
"protoc": {
// protoc.exe所在目录
"path": "C:\\Go\\bin\\protoc.exe",
// 保存时自动编译
"compile_on_save": true,
"options": [
// go编译输出指令
"--go_out=plugins=grpc:.",
"--govalidators_out=."
]
},
```
编译完成后，自动生成`simple.pb.go`和`simple.validator.pb.go`文件，`simple.pb.go`文件不再介绍，我们看下`simple.validator.pb.go`文件。
```go
// Code generated by protoc-gen-gogo. DO NOT EDIT.
// source: go-grpc-example/9-grpc_proto_validators/proto/simple.proto
package proto
import (
fmt "fmt"
math "math"
proto "github.com/golang/protobuf/proto"
_ "github.com/mwitkow/go-proto-validators"
regexp "regexp"
github_com_mwitkow_go_proto_validators "github.com/mwitkow/go-proto-validators"
)
// Reference imports to suppress errors if they are not otherwise used.
var _ = proto.Marshal
var _ = fmt.Errorf
var _ = math.Inf
func (this *InnerMessage) Validate() error {
if !(this.SomeInteger > 0) {
return github_com_mwitkow_go_proto_validators.FieldError("SomeInteger", fmt.Errorf(`value '%v' must be greater than '0'`, this.SomeInteger))
}
if !(this.SomeInteger < 100) {
return github_com_mwitkow_go_proto_validators.FieldError("SomeInteger", fmt.Errorf(`value '%v' must be less than '100'`, this.SomeInteger))
}
if !(this.SomeFloat >= 0) {
return github_com_mwitkow_go_proto_validators.FieldError("SomeFloat", fmt.Errorf(`value '%v' must be greater than or equal to '0'`, this.SomeFloat))
}
if !(this.SomeFloat <= 1) {
return github_com_mwitkow_go_proto_validators.FieldError("SomeFloat", fmt.Errorf(`value '%v' must be lower than or equal to '1'`, this.SomeFloat))
}
return nil
}
var _regex_OuterMessage_ImportantString = regexp.MustCompile(`^[a-z]{2,5}$`)
func (this *OuterMessage) Validate() error {
if !_regex_OuterMessage_ImportantString.MatchString(this.ImportantString) {
return github_com_mwitkow_go_proto_validators.FieldError("ImportantString", fmt.Errorf(`value '%v' must be a string conforming to regex "^[a-z]{2,5}$"`, this.ImportantString))
}
if nil == this.Inner {
return github_com_mwitkow_go_proto_validators.FieldError("Inner", fmt.Errorf("message must exist"))
}
if this.Inner != nil {
if err := github_com_mwitkow_go_proto_validators.CallValidatorIfExists(this.Inner); err != nil {
return github_com_mwitkow_go_proto_validators.FieldError("Inner", err)
}
}
return nil
}
```
里面自动生成了`message`中属性的验证规则。
### 把`grpc_validator`验证拦截器添加到服务端
```go
grpcServer := grpc.NewServer(cred.TLSInterceptor(),
grpc.StreamInterceptor(grpc_middleware.ChainStreamServer(
grpc_validator.StreamServerInterceptor(),
grpc_auth.StreamServerInterceptor(auth.AuthInterceptor),
grpc_zap.StreamServerInterceptor(zap.ZapInterceptor()),
grpc_recovery.StreamServerInterceptor(recovery.RecoveryInterceptor()),
)),
grpc.UnaryInterceptor(grpc_middleware.ChainUnaryServer(
grpc_validator.UnaryServerInterceptor(),
grpc_auth.UnaryServerInterceptor(auth.AuthInterceptor),
grpc_zap.UnaryServerInterceptor(zap.ZapInterceptor()),
grpc_recovery.UnaryServerInterceptor(recovery.RecoveryInterceptor()),
)),
)
```
运行后，当输入数据验证失败后，会有以下错误返回
```powershell
Call Route err: rpc error: code = InvalidArgument desc = invalid field SomeInteger: value '101' must be less than '100'
```
### 其他类型验证规则设置
`enum`验证
```protobuf
syntax = "proto3";
package proto;
import "github.com/mwitkow/go-proto-validators/validator.proto";
message SomeMsg {
Action do = 1 [(validator.field) = {is_in_enum : true}];
}
enum Action {
ALLOW = 0;
DENY = 1;
CHILL = 2;
}
```
`UUID`验证
```protobuf
syntax = "proto3";
package proto;
import "github.com/mwitkow/go-proto-validators/validator.proto";
message UUIDMsg {
// user_id must be a valid version 4 UUID.
string user_id = 1 [(validator.field) = {uuid_ver: 4, string_not_empty: true}];
}
```
### 总结
`go-grpc-middleware`中`grpc_validator`集成`go-proto-validators`，我们只需要在编写proto时设好验证规则，并把`grpc_validator`添加到gRPC服务端，就能完成gRPC的数据验证，很简单也很方便。
教程源码地址：https://github.com/Bingjian-Zhu/go-grpc-example
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