Class: ActiveRecord::Associations::JoinDependency::JoinAssociation

Inherits:
JoinPart
  • Object
show all
Defined in:
activerecord/lib/active_record/associations/join_dependency/join_association.rb

Overview

:nodoc:

Instance Attribute Summary collapse

Attributes inherited from JoinPart

#base_klass, #children

Instance Method Summary collapse

Methods inherited from JoinPart

#each, #extract_record, #instantiate, #name

Methods included from Enumerable

#as_json, #exclude?, #index_by, #many?, #sum

Constructor Details

#initialize(reflection, children) ⇒ JoinAssociation

Returns a new instance of JoinAssociation.



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# File 'activerecord/lib/active_record/associations/join_dependency/join_association.rb', line 12

def initialize(reflection, children)
  super(reflection.klass, children)

  @reflection      = reflection
  @tables          = nil
end

Instance Attribute Details

#reflection ⇒ Object (readonly)

The reflection of the association represented



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# File 'activerecord/lib/active_record/associations/join_dependency/join_association.rb', line 8

def reflection
  @reflection
end

#tables ⇒ Object

Returns the value of attribute tables



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# File 'activerecord/lib/active_record/associations/join_dependency/join_association.rb', line 10

def tables
  @tables
end

Instance Method Details

#aliased_table_name ⇒ Object 



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# File 'activerecord/lib/active_record/associations/join_dependency/join_association.rb', line 112

def aliased_table_name
  table.table_alias || table.name
end

#build_constraint(klass, table, key, foreign_table, foreign_key) ⇒ Object

Builds equality condition.

Example:

class Physician < ActiveRecord::Base
  has_many :appointments
end

If I execute `Physician.joins(:appointments).to_a` then
  reflection    # => #<ActiveRecord::Reflection::AssociationReflection @macro=:has_many ...>
  table         # => #<Arel::Table @name="appointments" ...>
  key           # =>  physician_id
  foreign_table # => #<Arel::Table @name="physicians" ...>
  foreign_key   # => id



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# File 'activerecord/lib/active_record/associations/join_dependency/join_association.rb', line 95

def build_constraint(klass, table, key, foreign_table, foreign_key)
  constraint = table[key].eq(foreign_table[foreign_key])

  if klass.finder_needs_type_condition?
    constraint = table.create_and([
      constraint,
      klass.send(:type_condition, table)
    ])
  end

  constraint
end

#join_constraints(foreign_table, foreign_klass, node, join_type, tables, scope_chain, chain) ⇒ Object 



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# File 'activerecord/lib/active_record/associations/join_dependency/join_association.rb', line 24

def join_constraints(foreign_table, foreign_klass, node, join_type, tables, scope_chain, chain)
  joins         = []
  tables        = tables.reverse

  scope_chain_index = 0
  scope_chain = scope_chain.reverse

  # The chain starts with the target table, but we want to end with it here (makes
  # more sense in this context), so we reverse
  chain.reverse_each do |reflection|
    table = tables.shift
    klass = reflection.klass

    case reflection.source_macro
    when :belongs_to
      key         = reflection.association_primary_key
      foreign_key = reflection.foreign_key
    else
      key         = reflection.foreign_key
      foreign_key = reflection.active_record_primary_key
    end

    constraint = build_constraint(klass, table, key, foreign_table, foreign_key)

    scope_chain_items = scope_chain[scope_chain_index].map do |item|
      if item.is_a?(Relation)
        item
      else
        ActiveRecord::Relation.create(klass, table).instance_exec(node, &item)
      end
    end
    scope_chain_index += 1

    scope_chain_items.concat [klass.send(:build_default_scope, ActiveRecord::Relation.create(klass, table))].compact

    rel = scope_chain_items.inject(scope_chain_items.shift) do |left, right|
      left.merge right
    end

    if reflection.type
      constraint = constraint.and table[reflection.type].eq foreign_klass.base_class.name
    end

    if rel && !rel.arel.constraints.empty?
      constraint = constraint.and rel.arel.constraints
    end

    joins << table.create_join(table, table.create_on(constraint), join_type)

    # The current table in this iteration becomes the foreign table in the next
    foreign_table, foreign_klass = table, klass
  end

  joins
end

#match?(other) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'activerecord/lib/active_record/associations/join_dependency/join_association.rb', line 19

def match?(other)
  return true if self == other
  super && reflection == other.reflection
end

#table ⇒ Object 



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# File 'activerecord/lib/active_record/associations/join_dependency/join_association.rb', line 108

def table
  tables.first
end