README.md

Validation Errors

import "github.com/infobloxopen/atlas-app-toolkit/errors/mappers/validationerrors"

validationerrors is a request contents validator server-side middleware for gRPC.

Request Validator Middleware

This middleware checks for the existence of a Validate method on each of the messages of a gRPC request. In case of a validation failure, an InvalidArgument gRPC status is returned, along with the error that caused the validation failure.

It is intended to be used with plugins like https://github.com/lyft/protoc-gen-validate, Go protocol buffers codegen plugins that create the Validate methods (including nested messages) based on declarative options in the .proto files themselves.

Usage

func UnaryServerInterceptor

func UnaryServerInterceptor() grpc.UnaryServerInterceptor

UnaryServerInterceptor returns a new unary server interceptor that validates incoming messages and returns a ValidationError.

Invalid messages will be rejected with InvalidArgument and the error before reaching any userspace handlers.

func DefaultMapping

func DefaultMapping() errors.MapFunc

DefaultMapping returns a mapper that parses through the lyft protoc-gen-validate errors and only returns a user friendly error.

Example Usage:

1. Add validationerrors and errors interceptors to your application:

   errors.UnaryServerInterceptor(ErrorMappings...),
   validationerrors.UnaryServerInterceptor(),

2. Create an ErrorMapping variable with all your mappings.

3. Add DefaultMapping as part of your ErrorMapping variable

   var ErrorMappings = []errors.MapFunc{
      // Adding Default Validations Mapping
      validationerrors.DefaultMapping(), 
   
   }

   Example return after DefaultMapping on a invalid email:

   {
       "error": {
           "status": 400,
           "code": "INVALID_ARGUMENT",
           "message": "Invalid primary_email: value must be a valid email address"
       },
       "fields": {
           "primary_email": [
               "value must be a valid email address"
           ]
       }
   }

4. You can also add custom validation mappings:

   var ErrorMappings = []errors.MapFunc{
       // Adding custom Validation Mapping based on the known field and reason from lyft
      errors.NewMapping(
   		errors.CondAnd(
   			validationerrors.CondValidation(),
               validationerrors.CondFieldEq("primary_email"),
   			validationerrors.CondReasonEq("value must be a valid email address"),
   		),
   		errors.MapFunc(func(ctx context.Context, err error) (error, bool) {
   			vErr, _ := err.(validationerrors.ValidationError)
   			return errors.NewContainer(codes.InvalidArgument, "Custom error message for field: %v reason: %v", vErr.Field(), vErr.Reason()), true
           }),
      ),
   }

For actual example usage look at: https://github.com/infobloxopen/atlas-contacts-app