# What is this code add\_to\_serializer in all these plugins

**URL:** <https://meta.discourse.org/t/what-is-this-code-add-to-serializer-in-all-these-plugins/58913>\
**Category:** Development\
**Created:** [3월 12, 2017, 5:07오전 UTC](https://meta.discourse.org/t/what-is-this-code-add-to-serializer-in-all-these-plugins/58913 "2017-03-12T05:07:15Z")\
**Posts on this page:** 1\
**Showing post:** 1

<div class="post-metadata">

**Author:** ![net\_deamon](https://sea3.discourse-cdn.com/meta/user_avatar/meta.discourse.org/net_deamon/32/70126_2.png) [@net\_deamon](https://meta.discourse.org/u/net_deamon)\
**Post date:** [3월 12, 2017, 5:07오전 UTC](https://meta.discourse.org/t/what-is-this-code-add-to-serializer-in-all-these-plugins/58913/1 "2017-03-12T05:07:15Z")

</div>

I have seen this code in [discourse\_signatures plugin](https://github.com/xfalcox/discourse-signatures/blob/master/plugin.rb#L20)

```rb
User.register_custom_field_type('see_signatures', :boolean)
User.register_custom_field_type('signature_url', :text)
User.register_custom_field_type('signature_raw', :text)

if SiteSetting.signatures_enabled then
  add_to_serializer(:post, :user_signature, false) {
    if SiteSetting.signatures_advanced_mode then
      object.user.custom_fields['signature_raw']
    else
      object.user.custom_fields['signature_url']
    end
  }

  # I guess this should be the default @ discourse. PR maybe?
  add_to_serializer(:user, :custom_fields, false) {
    if object.custom_fields == nil then
      {}
    else
      object.custom_fields
    end
  }
end

```

In [discourse national flags plugin](https://github.com/Ebsy/discourse-nationalflags/blob/master/plugin.rb#L27)

```rb
User.register_custom_field_type('nationalflag_iso', :text)

if SiteSetting.nationalflag_enabled then
  byebug;
  add_to_serializer(:post, :user_signature, false) {
    object.user.custom_fields['nationalflag_iso']
  }
  byebug;
  # I guess this should be the default @ discourse. PR maybe?
  add_to_serializer(:user, :custom_fields, false) {
    if object.custom_fields == nil then
      {}
    else
      object.custom_fields
    end
  }
end

```

I am not able to understand what is `add_to_serializer` is doing.

**I checked in def add\_to\_serializer**

```rb
def add_to_serializer(serializer, attr, define_include_method=true, &block)
  klass = "#{serializer.to_s.classify}Serializer".constantize rescue "#{serializer.to_s}Serializer".constantize

  klass.attributes(attr) unless attr.to_s.start_with?("include_")

  klass.send(:define_method, attr, &block)

  return unless define_include_method

  # Don't include serialized methods if the plugin is disabled
  plugin = self
  klass.send(:define_method, "include_#{attr}?") { plugin.enabled? }
end

```

I understand that `User.register_custom_field_type('signature_raw', :text)` will register a custom field type to `User` object. But what is `add_to_serializer` doing? I am not able to understand, can you explain me in plain english?

---

_[View the full topic](https://meta.discourse.org/t/what-is-this-code-add-to-serializer-in-all-these-plugins/58913)._