https://github.com/envoyproxy/protoc-gen-validate

This project is currently in alpha. The API should be considered unstable and likely to change

PGV is a protoc plugin to generate polyglot message validators. While protocol buffers effectively guarantee the types of structured data, they cannot enforce semantic rules for values. This plugin adds support to protoc-generated code to validate such constraints.

Developers import the PGV extension and annotate the messages and fields in their proto files with constraint rules:

syntax = "proto3";

package examplepb;

import "validate/validate.proto";

message Person {
  uint64 id    = 1 [(validate.rules).uint64.gt    = 999];

  string email = 2 [(validate.rules).string.email = true];

  string name  = 3 [(validate.rules).string = {
                      pattern:   "^[^[0-9]A-Za-z]+( [^[0-9]A-Za-z]+)*$",
                      max_bytes: 256,
                   }];

  Location home = 4 [(validate.rules).message.required = true];

  message Location {
    double lat = 1 [(validate.rules).double = { gte: -90,  lte: 90 }];
    double lng = 2 [(validate.rules).double = { gte: -180, lte: 180 }];
  }
}

Executing protoc with PGV and the target language’s default plugin will create Validate methods on the generated types:

p := new(Person)

err := p.Validate() // err: Id must be greater than 999
p.Id = 1000

err = p.Validate() // err: Email must be a valid email address
p.Email = "example@lyft.com"

err = p.Validate() // err: Name must match pattern '^[^ds]+( [^ds]+)*$'
p.Name = "Protocol Buffer"

err = p.Validate() // err: Home is required
p.Home = &Location{37.7, 999}

err = p.Validate() // err: Home.Lng must be within [-180, 180]
p.Home.Lng = -122.4

err = p.Validate() // err: nil

This project is currently in alpha. The API should be considered unstable and likely to change

PGV is a protoc plugin to generate polyglot message validators. While protocol buffers effectively guarantee the types of structured data, they cannot enforce semantic rules for values. This plugin adds support to protoc-generated code to validate such constraints.

Developers import the PGV extension and annotate the messages and fields in their proto files with constraint rules:

syntax = "proto3";

package examplepb;

import "validate/validate.proto";

message Person {
  uint64 id    = 1 [(validate.rules).uint64.gt    = 999];

  string email = 2 [(validate.rules).string.email = true];

  string name  = 3 [(validate.rules).string = {
                      pattern:   "^[^[0-9]A-Za-z]+( [^[0-9]A-Za-z]+)*$",
                      max_bytes: 256,
                   }];

  Location home = 4 [(validate.rules).message.required = true];

  message Location {
    double lat = 1 [(validate.rules).double = { gte: -90,  lte: 90 }];
    double lng = 2 [(validate.rules).double = { gte: -180, lte: 180 }];
  }
}

Executing protoc with PGV and the target language’s default plugin will create Validate methods on the generated types:

p := new(Person)

err := p.Validate() // err: Id must be greater than 999
p.Id = 1000

err = p.Validate() // err: Email must be a valid email address
p.Email = "example@lyft.com"

err = p.Validate() // err: Name must match pattern '^[^ds]+( [^ds]+)*$'
p.Name = "Protocol Buffer"

err = p.Validate() // err: Home is required
p.Home = &Location{37.7, 999}

err = p.Validate() // err: Home.Lng must be within [-180, 180]
p.Home.Lng = -122.4

err = p.Validate() // err: nil