diff --git a/pkg/expr/expr_types.go b/pkg/expr/expr_types.go
index eb7b709e1..d643de0d9 100644
--- a/pkg/expr/expr_types.go
+++ b/pkg/expr/expr_types.go
@@ -3,6 +3,7 @@ package expr
 import (
 	"bytes"
 	"context"
+	"encoding/json"
 	"fmt"
 	"github.com/cortezaproject/corteza-server/pkg/errors"
 	"github.com/cortezaproject/corteza-server/pkg/handle"
@@ -144,6 +145,10 @@ func (t Array) Select(k string) (TypedValue, error) {
 	}
 }
 
+func (t ID) MarshalJSON() ([]byte, error) {
+	return json.Marshal(fmt.Sprintf("%d", t.value))
+}
+
 func CastToBoolean(val interface{}) (out bool, err error) {
 	return cast.ToBoolE(UntypedValue(val))
 }