Table of Contents

General

Models created during deserialization can access their immediate parent and the document root via two special accessors:

  • __parent:: The direct parent model instance

  • __root:: The top-level/root model instance

These accessors are automatically assigned during deserialization, enabling nested child models to reference their context within the model hierarchy.

root via two special accessors added:

  • __parent:: The direct parent model instance

  • __root:: The top-level/root model instance

These are assigned during deserialization so nested child models can reference context.

class Tag < Lutaml::Model::Serializable
  attribute :text, :string

  xml do
    root "Tag"

    map_content to: :text
  end

  key_value do
    map "text", to: :text
  end
end

class Tags < Lutaml::Model::Serializable
  attribute :tag, Tag, collection: true

  xml do
    root "Tags"

    map_element "Tag", to: :tag
  end

  key_value do
    map "Tag", to: :tag
  end
end

class Post < Lutaml::Model::Serializable
  attribute :tags, Tags, collection: true

  xml do
    root "Post"
    map_element "Tags", to: :tags
  end

  key_value do
    map "Tags", to: :tags
  end
end

post = Post.from_xml(<<~XML)
<Post>
  <Tags>
    <Tag>ruby</Tag>
    <Tag>coding</Tag>
  </Tags>
  <Tags>
    <Tag>JSON</Tag>
    <Tag>coding</Tag>
  </Tags>
</Post>
XML

first_tag = post.tags.first.tag.first # #<Tag:0x00000002e661a650 @text="ruby">
first_tag.__parent # #<Tags:0x00000002e5e90010 @tag=[#<Tag:0x00000002e5e5bb80 @text="ruby">, #<Tag:0x00000002e5e58ca0 @text="coding">]>
first_tag.__root # should return the `post` object

# Key-value formats also set these accessors
yaml = {
  "Tags" => [
    {
      "Tag" => [
        { "text" => "ruby" },
        { "text" => "coding"}
      ]
    },
    {
      "Tag" => [
        { "text" => "JSON" },
        { "text" => "coding" }
      ]
    }
  ]
}.to_yaml
post2 = Post.from_yaml(yaml)
# Same as explained in XML `post` example
post2.tags.first.__parent
post2.tags.first.__root
If you manually instantiate models, you can set these accessors yourself if needed: 
child.__parent = parent
child.__root   = parent.__root || parent