Class: YamlExporter::Nodes::ManyThrough

Inherits:
ManyBase
  • Object
show all
Defined in:
lib/yaml_exporter/nodes/many_through.rb

Overview

many :assoc, through: :join, find_by: :column do ... end.

With a block, its attributes (and any positioned_by column) attach to the JOIN row, not the target record. find_by resolves the target globally.

With NO block at all the association is a bare reference list: each entry is just the target's find_by value (a string), exactly like ManyReference, but routed through a join model. The join rows are still created/destroyed by the DSL, and positioned_by: — when given — derives the join's position column from the YAML order. An empty block is NOT the reference flavor: passing a block (empty or not) opts into the hash-shaped entries, same as the other many flavors.

Instance Attribute Summary collapse

Attributes inherited from ManyBase

#find_by, #name, #owner_class, #positioned_by, #sub_structure

Instance Method Summary collapse

Methods inherited from ManyBase

#build_child, #destroy_missing, #phase, #sort_for_export, #target_class, #yaml_keys

Constructor Details

#initialize(name:, owner_class:, through:, find_by:, positioned_by: nil, &block) ⇒ ManyThrough

Returns a new instance of ManyThrough.



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# File 'lib/yaml_exporter/nodes/many_through.rb', line 21

def initialize(name:, owner_class:, through:, find_by:, positioned_by: nil, &block)
  # Whether a block was passed (even an empty one) decides the YAML
  # shape: block → hash entries, no block → bare reference list.
  @reference_list = block.nil?
  block ||= proc {}

  @through = through.to_sym
  join_reflection = owner_class.reflect_on_association(@through)
  unless join_reflection
    raise ArgumentError,
          "`many #{name.inspect}`: #{owner_class} has no join association `#{through}`"
  end

  super(name: name, owner_class: owner_class, find_by: find_by,
        positioned_by: positioned_by, &block)
end

Instance Attribute Details

#through ⇒ Object (readonly)

Returns the value of attribute through.



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# File 'lib/yaml_exporter/nodes/many_through.rb', line 19

def through
  @through
end

Instance Method Details

#current_entries(parent) ⇒ Object

Existing "children" for destroy-missing bookkeeping are the join rows, not the targets: removing a reviewer must drop the join row, never the Reviewer itself. Order follows the through association's default scope (matching is by source-association object, not index, so order doesn't affect correctness here).



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# File 'lib/yaml_exporter/nodes/many_through.rb', line 59

def current_entries(parent)
  parent.association(@through).reset
  parent.public_send(@through).to_a
end

#default_export_order(records) ⇒ Object 



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# File 'lib/yaml_exporter/nodes/many_through.rb', line 87

def default_export_order(records)
  records.sort_by do |join|
    target = join.public_send(source_association_name)
    target.public_send(@find_by).to_s
  end
end

#entry_class ⇒ Object

Block attributes live on the join row.



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# File 'lib/yaml_exporter/nodes/many_through.rb', line 50

def entry_class
  join_class
end

#export(parent, exporter:) ⇒ Object

The collection the Exporter should walk is the join rows, since block attributes belong to those.



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# File 'lib/yaml_exporter/nodes/many_through.rb', line 96

def export(parent, exporter:)
  records = sort_for_export(Array(parent.public_send(@through)))
  if reference_list?
    keys = records.map { |join| join.public_send(source_association_name).public_send(@find_by) }
    return [@name.to_s, keys]
  end

  list = records.map do |join|
    target = join.public_send(source_association_name)
    hash = { @find_by.to_s => target.public_send(@find_by) }
    hash.merge!(exporter.build_hash(join, @sub_structure))
    hash
  end
  [@name.to_s, list]
end

#extra_entry_keys ⇒ Object 



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# File 'lib/yaml_exporter/nodes/many_through.rb', line 146

def extra_entry_keys
  [@find_by.to_s]
end

#extra_entry_schema ⇒ Object

find_by is a column on the target (e.g. Reviewer.slug), not on the join row — so resolve the type against target_class.



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# File 'lib/yaml_exporter/nodes/many_through.rb', line 152

def extra_entry_schema
  { @find_by => { type: TypeInference.schema_type_for(target_class, @find_by) } }
end

#find_or_build_child(parent, entry, _index, existing:) ⇒ Object 



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# File 'lib/yaml_exporter/nodes/many_through.rb', line 64

def find_or_build_child(parent, entry, _index, existing:)
  key = entry[@find_by.to_s]
  target = target_class.find_by(@find_by => key)
  unless target
    raise ActiveRecord::RecordNotFound,
          "no #{target_class} with #{@find_by}=#{key.inspect}"
  end

  # Match existing join rows by comparing the source association
  # object (AR `==` compares primary keys internally, so this works
  # for surrogate ids and composite PKs alike — no `target.id` needed).
  assoc = source_association_name
  match = existing.find { |join| join.public_send(assoc) == target }
  return match if match

  # `parent.<through>.build` sets the through-side FK for us (respects
  # `association_primary_key`); then we assign the target via its own
  # association setter rather than poking `*_id` columns.
  parent.public_send(@through).build.tap do |join|
    join.public_send("#{assoc}=", target)
  end
end

#import(parent, data, path:, importer:) ⇒ Object

Bare reference-list import: entries are find_by values, not hashes. The block-driven flow in ManyBase#import only applies when there are block attributes to write onto the join row.



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# File 'lib/yaml_exporter/nodes/many_through.rb', line 115

def import(parent, data, path:, importer:)
  return super unless reference_list?

  raw = data.key?(@name.to_s) ? data[@name.to_s] : nil
  values = raw.nil? ? [] : raw

  unless values.is_a?(Array)
    raise UnknownAttributeError,
          "#{list_path(path)}: expected a list, got #{values.class}"
  end
  unless values.all? { |v| v.is_a?(String) || v.is_a?(Symbol) || v.is_a?(Numeric) }
    raise UnknownAttributeError,
          "#{list_path(path)}: expected a list of #{@find_by} values, got #{raw.inspect}"
  end

  parent.association(@through).reset
  existing = current_entries(parent)
  kept = Set.new.compare_by_identity

  values.each_with_index do |value, index|
    join = find_or_build_child(parent, { @find_by.to_s => value }, index, existing: existing)
    # positioned_by is DSL-owned: derived from the 1-based array index,
    # mirroring ManyBase#import.
    join.public_send("#{@positioned_by}=", index + 1) if @positioned_by
    join.save!
    kept << join
  end

  destroy_missing(existing, kept)
end

#join_class ⇒ Object 



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# File 'lib/yaml_exporter/nodes/many_through.rb', line 45

def join_class
  @join_class ||= @owner_class.reflect_on_association(@through).klass
end

#reference_list? ⇒ Boolean

No block was passed → the YAML is a flat list of find_by values rather than a list of hashes. Mirrors ManyReference, but join rows (and their positioned_by column) are still managed by the DSL.

Returns:

  • (Boolean) 


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# File 'lib/yaml_exporter/nodes/many_through.rb', line 41

def reference_list?
  @reference_list
end

#schema_fragment ⇒ Object

A bare reference list is a flat array of find_by values; the block-driven object-array schema from ManyBase doesn't apply.



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# File 'lib/yaml_exporter/nodes/many_through.rb', line 158

def schema_fragment
  return super unless reference_list?

  item_type = TypeInference.schema_type_for(target_class, @find_by)
  { @name => { type: 'array', items: { type: item_type } } }
end