所有这些插件中的 add_to_serializer 这个代码是什么

开发
1

I have seen this code in discourse_signatures plugin

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

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

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?

2

It’s essentially adding to the information that Discourse serializes out when sending that model to the client. For example, you may see a request to this endpoint when loading up a topic page:

http://meta.discourse.org/t/2349082394.json

which returns some payload like this:

{
  title: "Some topic title",
  archetype: 'regular',
  category_id: 7,
  post_stream: { posts: [...] },
  posts_count: 15,
  (etc etc.. lots more info about the topic in question)
}

Which is the json representation of a Discourse topic.

If I want to know more about the topic because of additional ‘stuff’ I do in my plugin, I can put in a line like

add_to_serializer :topic, :flag_name do
  object.flag_name # <- NB that 'object' here is the topic being serialized
end

(Also, by default, this method simply sends the specified message to ‘object’, meaning that

add_to_serializer :topic, :flag_name

is the same as

add_to_serializer :topic, :flag_name do
  object.flag_name
end

)

Once I’ve added the method to the serializer, I can end up with JSON output which includes that additional info

{
  title: "Some topic title",
  archetype: 'regular',
  category_id: 7,
  post_stream: { posts: [...] },
  posts_count: 15,
  flag_name: "some flag name"
  ...
}

Also note that you could achieve the same thing by overwriting the TopicSerializer class (which is exactly what the code snippet you’ve provided is doing)

# plugin.rb
TopicSerializer.class_eval do
  attributes :flag_name
  def flag_name
    object.flag_name
  end
end
4

Hi,
When running the following code,

TopicSerializer.class_eval do
  attributes :flag_name
  def flag_name
    object.flag_name
  end
end

I was getting the error “block in activate!’: uninitialized constant TopicSerializer (NameError)”. I think I have to “import” or “require” the TopicSerializer dependency. Can you please tell me what would be the dependency, as I am not able to figure it out.

5

Add this directly above your code require_dependency 'topic_serializer'

require_dependency 'topic_serializer'
class ::TopicSerializer
  attributes :flag_name
  def flag_name
    object.flag_name
  end
end
6

Hi thanks, but I got the error " `load’: No such file to load – topic_serializer (LoadError)". Does it pull from the app/serializers folder? I checked in that folder, I could find topic_list_serializer.rb, and many other related to topic, but couldnt find topic_serializer.rb

7

Right! Try TopicViewSerializer.

require_dependency 'topic_view_serializer'
class ::TopicViewSerializer
  attributes :flag_name
  def flag_name
    object.flag_name
  end
end
8

嘿，我在类别编辑框中添加了一个自定义字段。

提交表单时，我在 JS 控制台中看到这些字段被提交了：
custom_fields[default_tag][]:good-feedback custom_fields[default_tag][]:one-more-tag

在我的主插件文件中，我写了：

add_to_serializer(:basic_category, :default_tag){object.custom_fields[“default_tag”]}

但我的自定义字段并没有保存到数据库中。

9

现在执行：

add_to_serializer(:basic_category, :default_tag, false ){object.custom_fields["default_tag"]}

是否有效？

11

我当时通过为 :before_action 事件添加一个函数解决了这个问题，将数组转换为分隔字符串，并在检索时再将其转换回来。

我并没有深入探究为什么数组不能直接作为自定义字段存储。

12

那么，这或许能简化代码？

13

是的，如果在这种情况下能行得通的话。我稍后试一下，再回复你。

14

可怜你，当时一定很疼吧 :wink:

15

那是一个周日的晚上，好奇心占了上风。过程有些痛苦，但也很有趣。
这是 @pfaffman 当时正试图做的事情。

没有痛苦就没有收获 :wink:

16

哈哈，太对了！…

17

你好，我也遇到了同样的问题（custom_fields 在 JS 控制台中已提交，但未能保存到数据库）。我在主插件文件中使用了 add_to_serializer(:basic_category, :default_tag, false ){object.custom_fields["default_tag"]} 这种方式。

您仍然推荐这个解决方案吗？

18

这里出现了很多问题。首先，是哪些自定义字段？

19

我正在开发一个插件，用于自动化 Discourse 群组与 LDAP 的同步。我为 Group 添加了一个自定义字段（ldap_dn），用于保存 LDAP 群组名称。我试图从我在 membership plugin-outlet 中添加的输入字段中获取 custom_field 的值，并将其保存到数据库中，以便后续使用。

为此，我在 plugin.rb 文件中添加了以下内容：

Group.register_custom_field_type(‘ldap_dn’, :text)
Group.preload_custom_fields << “ldap_dn” if
Group.respond_to? :preloaded_custom_fields

if SiteSetting.groups_sync_enabled then
add_to_serializer(:group_show, :custom_fields, false) {
object.custom_fields
}
end

作为 Rails 和 Ember 的新手，我不确定是否还有其他步骤需要执行，以便将 custom_fields 保存到数据库中，或者问题出在哪里。

20

我认为，如果你在 plugin.rb 中添加
register_editable_group_custom_field 'field_name'
应该就能解决问题。

注意：
Serializer 用于将数据发送给客户端，而不是接收数据。

21

啊，好的！我是新手，所以这可能是个特别“显而易见”的问题，但为了接收数据，我需要通过 API 来获取吗？

22

我的解决方案会在数据到达服务器时，为字段发出绿灯信号。因此，这关乎于接收数据。