templates/grpc_validate

import (
  grpc_codes "google.golang.org/grpc/codes"
  grpc_status "google.golang.org/grpc/status"
)

{{ $decorator := (or .Vars.DecoratorName (printf "%sWithGRPCValidation" .Interface.Name)) }}

// {{$decorator}} implements {{.Interface.Type}} interface instrumented with GRPC request validation
type {{$decorator}} struct {
  {{.Interface.Type}}
}

// New{{$decorator}} returns {{$decorator}}
func New{{$decorator}} (base {{.Interface.Type}}) {{$decorator}} {
  return {{$decorator}} {
    {{.Interface.Name}}: base,
  }
}

{{range $method := .Interface.Methods}}
  {{- if $method.ReturnsError}}
  // {{$method.Name}} implements {{$.Interface.Type}}
  func (_d {{$decorator}}) {{$method.Declaration}} {
    {{- range $param := $method.Params}}
      {{- if not ( and $method.AcceptsContext (eq $param.Name "ctx")) -}}
        if _v, _ok := interface{}({{$param.Name}}).(interface{ Validate() error}); _ok {
          if err = _v.Validate(); err != nil {
            err = grpc_status.Error(grpc_codes.InvalidArgument, err.Error())
            return
          }
        }
      {{end}}
    {{end}}
    {{$method.Pass (printf "_d.%s." $.Interface.Name) }}
  }
  {{end}}
{{end}}