protovalidate-kt

Kotlin code generation for protovalidate (buf.validate) and protoc-gen-validate (PGV) constraints.

Generates Kotlin validation functions from protobuf constraint annotations at compile time via a protoc plugin. Includes a lightweight runtime library for common validation logic.

Modules

Module	Description
runtime	Validation helper functions used by generated code
protoc-plugin-core	Shared code generator logic (field emitters, CEL transpiler)
protoc-plugin	protoc plugin for PGV (validate/validate.proto) constraints
protoc-plugin-buf	protoc plugin for buf validate (buf/validate/validate.proto) constraints
gradle-plugin	Gradle plugin that wires everything together for consumers
conformance	Buf protovalidate conformance test executor
pgv-conformance	PGV conformance test executor

Setup

Gradle Plugin

The simplest way to use protovalidate-kt. Requires the protobuf-gradle-plugin.

plugins {
    id("com.google.protobuf") version "0.9.6"
    id("dev.bmcreations.protovalidate") version "<version>"
}

This automatically:

• Registers the protoc plugin for code generation
• Adds the runtime dependency
• Configures generateProtoTasks to invoke the plugin

By default the buf validate variant is used. To use PGV instead:

import dev.bmcreations.protovalidate.gradle.ProtoVariant

protovalidate {
    variant.set(ProtoVariant.PGV)
}

buf validate (recommended)

buf validate is the actively-maintained successor to PGV. Protos use buf.validate annotations:

import "buf/validate/validate.proto";

message User {
  string email = 1 [(buf.validate.field).string.email = true];
  uint32 age = 2 [(buf.validate.field).uint32 = {gte: 0, lte: 150}];
}

PGV (legacy)

protoc-gen-validate uses validate annotations:

import "validate/validate.proto";

message User {
  string email = 1 [(validate.rules).string.email = true];
  uint32 age = 2 [(validate.rules).uint32 = {gte: 0, lte: 150}];
}

PGV protos import validate/validate.proto. If protoc can't find it, add the proto include path. The Gradle plugin handles this automatically when using ProtoVariant.PGV.

Manual setup (without the Gradle plugin)

If you prefer to configure things yourself:

dependencies {
    implementation("dev.bmcreations.protovalidate:runtime:<version>")
}

protobuf {
    plugins {
        // The protobuf-gradle-plugin auto-generates a wrapper script for JAR artifacts
        create("validate-kt-buf") {
            artifact = "dev.bmcreations.protovalidate:protoc-plugin-buf:<version>@jar"
        }
    }
    generateProtoTasks {
        all().forEach {
            it.plugins { create("validate-kt-buf") }
        }
    }
}

For PGV, replace validate-kt-buf / protoc-plugin-buf with validate-kt / protoc-plugin.

Conformance

buf protovalidate (2872/2872 passing)

./gradlew :conformance:jar
conformance/run-conformance.sh

PGV (1053/1053 passing)

./gradlew :pgv-conformance:jar
cd pgv-conformance && ./run-conformance.sh

Building

Requires JDK 21+.

./gradlew build

License

MIT