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Class: Mongoid::Association::EagerLoad::InclusionTree Private

Relationships & Source Files
Inherits: Object
Defined in: lib/mongoid/association/eager_load/inclusion_tree.rb

Overview

The tree of nested inclusions an eager load asks to load. Built from the criteria's inclusions, it contributes each root node's stages to the pipeline, with each node already carrying its own children.

Each root branch is built from its own copy of the inclusions, and an inclusion is removed as it is placed, so it lands once per branch even if more than one parent in that branch points at it, and a circular chain of inclusions can't loop forever.

Class Method Summary

Instance Method Summary

  • #contribute_to(destination) Internal use only

    Contribute each root inclusion's stages to the pipeline.

  • #node(association, available) private Internal use only
  • #roots private Internal use only

    A name that more than one subclass defines (with different targets) can't share one $lookup field, so its nodes -- each carrying its own children -- are grouped and routed by the discriminator instead of becoming separate, overwriting roots.

  • #same_hierarchy?(one, other) ⇒ Boolean private Internal use only

    Whether two classes belong to the same inheritance chain (one is the other, an ancestor of it, or a descendant of it).

  • #take_children(association, available) private Internal use only

    The still-available inclusions parented to association, removed as they are taken so each lands once on this branch.

  • #top_level private Internal use only

    The inclusions that no other inclusion is the parent of.

Constructor Details

.new(inclusions, pipeline, by_name) ⇒ InclusionTree

[ GitHub ] 

  


# File 'lib/mongoid/association/eager_load/inclusion_tree.rb', line 34



def initialize(inclusions, pipeline, by_name)
  @inclusions = inclusions
  @pipeline = pipeline
  @by_name = by_name
end


  







Class Method Details



  

    .from(inclusions, pipeline)  ⇒ InclusionTree 
  



  

    
Builds the tree for the criteria's inclusions.

  





  
Parameters:



Returns:


    
  
  • 
    (InclusionTree)
—    
    The tree.
    
  
    • 





  [ GitHub ]


  

  


# File 'lib/mongoid/association/eager_load/inclusion_tree.rb', line 27



def from(inclusions, pipeline)
  new(inclusions, pipeline, inclusions.to_h { |association| [ association.name, association ] })
end


  







Instance Method Details



  

    #contribute_to(destination)  
  



  

    
Contribute each root inclusion's stages to the pipeline. Each root carries
its own children, so the whole tree is appended by recursion from the
roots downward.

  





  
Parameters:


    
  
  • 
    destination
    (Array<Hash>)
—    
    The pipeline the stages are appended to.
    
  
    • 





  [ GitHub ]


  

  


# File 'lib/mongoid/association/eager_load/inclusion_tree.rb', line 45



def contribute_to(destination)
  roots.each { |root| root.contribute(destination, []) }
end


  








  

    #node(association, available)   (private)
  

  [ GitHub ]


  

  


# File 'lib/mongoid/association/eager_load/inclusion_tree.rb', line 69



def node(association, available)
  children = take_children(association, available).map { |child| node(child, available) }
  AssociationInclusion.for(association, @pipeline, children)
end


  








  

    #roots   (private)
  



  

    
A name that more than one subclass defines (with different targets) can't
share one $lookup field, so its nodes -- each carrying its own children --
are grouped and routed by the discriminator instead of becoming separate,
overwriting roots.

  





  


  [ GitHub ]


  

  


# File 'lib/mongoid/association/eager_load/inclusion_tree.rb', line 55



def roots
  top_level.group_by(&:name).map do |_name, associations|
    nodes = associations.map { |association| node(association, @inclusions.dup) }
    nodes.one? ? nodes.first : DiscriminatedInclusion.new(nodes)
  end
end


  








  

    #same_hierarchy?(one, other)  ⇒ Boolean  (private)
  



  

    
Whether two classes belong to the same inheritance chain (one is the
other, an ancestor of it, or a descendant of it).

  





  


  [ GitHub ]


  

  


# File 'lib/mongoid/association/eager_load/inclusion_tree.rb', line 90



def same_hierarchy?(one, other)
  one <= other || other <= one
end


  








  

    #take_children(association, available)   (private)
  



  

    
The still-available inclusions parented to association, removed as they
are taken so each lands once on this branch. A child belongs here when it
names this association as its parent and its owner shares the target's
class hierarchy, which tells apart children of two unrelated subclasses
that share an association name.

  





  


  [ GitHub ]


  

  


# File 'lib/mongoid/association/eager_load/inclusion_tree.rb', line 79



def take_children(association, available)
  children = available.select do |candidate|
    candidate.parent_inclusions.include?(association.name) &&
      same_hierarchy?(association.klass, candidate.inverse_class)
  end
  available.reject! { |candidate| children.include?(candidate) }
  children
end


  








  

    #top_level   (private)
  



  

    
The inclusions that no other inclusion is the parent of.

  





  


  [ GitHub ]


  

  


# File 'lib/mongoid/association/eager_load/inclusion_tree.rb', line 63



def top_level
  @inclusions.reject do |association|
    association.parent_inclusions.any? { |name| @by_name.key?(name) }
  end
end