add core/error/util files

pkg/validators/not_blank.go

@@ -0,0 +1,17 @@
+package validators
+
+import (
+	"strings"
+
+	"github.com/go-playground/validator/v10"
+)
+
+func NotBlank(fl validator.FieldLevel) bool {
+	if value, ok := fl.Field().Interface().(string); ok {
+		if value != "" && strings.Trim(value, " ") != "" {
+			return true
+		}
+	}
+
+	return false
+}