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LaktaLakta

Request Validation

pkg/validation/fiber and pkg/validation/grpc add request validation to the HTTP and gRPC transports. Both fail as an *errors.AppError{Code: VALIDATION} carrying one field violation per failed field, so the Phase 5 error renderers produce byte-identical violation shapes across transports — application/problem+json with invalid_params for Fiber, codes.InvalidArgument + errdetails.BadRequest for gRPC.

Each lives in its own module (import aliased to avoid clashing with gofiber/fiber and google.golang.org/grpc):

import (
    valfiber "github.com/Vilsol/lakta/pkg/validation/fiber"
    valgrpc "github.com/Vilsol/lakta/pkg/validation/grpc"
)

Fiber

Section titled “Fiber”

valfiber.New builds a fiber.StructValidator backed by go-playground/validator/v10. Register it on the Fiber module via WithStructValidator; ctx.Bind().Body(&dto) then auto-invokes it, and a validate: struct-tag failure becomes a VALIDATION AppError.

fiberserver.NewModule(
    fiberserver.WithStructValidator(valfiber.New()),
)

Field paths in the rendered error are normalized to their json-tag dotted/bracketed form (user.email, items[0].qty) so they match the gRPC transport exactly.

Options

Section titled “Options”
Option Effect
valfiber.WithValidate(v *validator.Validate) Supply a pre-built validator instance (custom validators, aliases). Defaults to validator.New().
valfiber.WithTagName(name string) Override the rule-tag key. Defaults to "validate".

gRPC

Section titled “gRPC”

valgrpc.NewValidator compiles a protovalidate validator that runs CEL constraints declared in your .proto files. Wire the interceptors onto the gRPC server module:

v, err := valgrpc.NewValidator()
if err != nil {
    return err
}


grpcserver.NewModule(
    grpcserver.WithService(&v1.MyService_ServiceDesc, NewServer()),
    grpcserver.WithUnaryInterceptor(valgrpc.UnaryServerInterceptor(v)),
    grpcserver.WithStreamInterceptor(valgrpc.StreamServerInterceptor(v)),
)

The unary interceptor validates each request before the handler runs; the stream interceptor validates every message received on the stream. Non-proto requests are skipped. Pass an existing protovalidate.Validator to NewValidator to share compiled constraints across servers.

Violation reasons are normalized to the final segment of the CEL rule id (string.email → email) so they line up with validator/v10’s tag vocabulary on the Fiber side.