ProtoValidate 0.1.5

protovalidate-net

protovalidate-net is the C# implementation of protovalidate, designed to validate Protobuf messages at runtime based on user-defined validation constraints. Powered by Google's Common Expression Language (CEL), it provides a flexible and efficient foundation for defining and evaluating custom validation rules. The primary goal of protovalidate is to help developers ensure data consistency and integrity across the network without requiring generated code.

The protovalidate project

Head over to the core protovalidate repository for:

• The API definition: used to describe validation constraints
• Documentation: how to apply protovalidate effectively
• Migration tooling: incrementally migrate from protoc-gen-validate
• Conformance testing utilities: for acceptance testing of protovalidate implementations

Other protovalidate runtime implementations include:

• Go: protovalidate-go
• C++: protovalidate-cc
• Java: protovalidate-java

Installation

To install the package, use nuget:

nuget install ProtoValidate

Usage

This example shows how to use ProtoValidate-net with dependency injection Register ProtoValidate in your service collection and configure the options.

using ProtoValidate;

// register ProtoValidate with no options
serviceCollection.AddProtoValidate();

// OR register ProtoValidate with options
serviceCollection.AddProtoValidate(options => {       
    // This setting is used to configure if it loads your validation descriptors upon creation of the validator.
    // True will load on creation
    // False will defer loading the validator until first run of the validation logic for that type.
    options.PreLoadDescriptors = true;

    // This setting will cause a compilation exception to be thrown if the message type you are validating hasn't been pre-loaded using the file descriptor list.
    options.DisableLazy = true;

    //register your file descriptors generated by Google.Protobuf library for your compiled .proto files
    options.FileDescriptors = new List<FileDescriptor>() {
        //your list of Protobuf File Descriptors here
    }
});

Example on how to validate a message using the IValidator instance from the service provider

// define your Protobuf message that needs validation
var myMessageToValidate = new MyMessageThatNeedsValidation() {...};

// resolve IValidator from your service provider
// you can resolve it directly like this, or from the constructor using dependency injection
var validator = serviceProvider.GetRequiredService<ProtoValidate.IValidator>();

// flag to indicate if the validator should return on the first error (true) or validate all the fields and return all the errors in the message (false).
var failFast = true;

//validate the message
var violations = validator.Validate(myMessageToValidate, failFast);

//the violations contains the validation errors.
var hasViolations = violations.Violations.Count > 0;

Example on how to create a validator and validate a message without using dependency injection.

var validatorOptions = new ProtoValidate.ValidatorOptions() {
    // This setting is used to configure if it loads your validation descriptors upon creation of the validator.
    // True will load on creation
    // False will defer loading the validator until first run of the validation logic for that type.
    PreLoadDescriptors = true,

    // This setting will cause a compilation exception to be thrown if the message type you are validating hasn't been pre-loaded using the file descriptor list.
    DisableLazy = true,

    //register your file descriptors generated by Google.Protobuf library for your compiled .proto files
    FileDescriptors = new List<FileDescriptor>() {
        //your list of Protobuf File Descriptors here
    }
};

//Instantiate the validator.  You should cache the validator for reuse.
var validator = new ProtoValidate.Validator(validatorOptions);

// flag to indicate if the validator should return on the first error (true) or validate all the fields and return all the errors in the message (false).
var failFast = true;

// define your Protobuf message that needs validation
var myMessageToValidate = new MyMessageThatNeedsValidation() {...};

//validate the message
var violations = validator.Validate(myMessageToValidate, failFast);

//the violations contains the validation errors.
var hasViolations = violations.Violations.Count > 0;

Implementing validation constraints

Validation constraints are defined directly within .proto files. Documentation for adding constraints can be found in the protovalidate project README and its comprehensive docs.

syntax = "proto3";

package my.package;

import "google/protobuf/timestamp.proto";
import "buf/validate/validate.proto";

message Transaction {
  uint64 id = 1 [(buf.validate.field).uint64.gt = 999];
  google.protobuf.Timestamp purchase_date = 2;
  google.protobuf.Timestamp delivery_date = 3;

  string price = 4 [(buf.validate.field).cel = {
    id: "transaction.price",
    message: "price must be positive and include a valid currency symbol ($ or £)",
    expression: "(this.startswith('$') or this.startswith('£')) and float(this[1:]) > 0"
  }];

  option (buf.validate.message).cel = {
    id: "transaction.delivery_date",
    message: "delivery date must be after purchase date",
    expression: "this.delivery_date > this.purchase_date"
  };
}

Ecosystem

• protovalidate core repository
• Buf
• CEL Spec
• CEL C# implementation

Legal

Offered under the Apache 2 license.