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

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

Overview

:nodoc:

Defined Under Namespace

Classes: JoinInformation

Instance Attribute Summary collapse

Attributes inherited from JoinPart

#base_klass, #children

Instance Method Summary collapse

Methods inherited from JoinPart

#each, #extract_record, #instantiate, #name

Constructor Details

#initialize(reflection, children) ⇒ JoinAssociation

Returns a new instance of JoinAssociation.


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# File '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

#reflectionObject (readonly)

The reflection of the association represented


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

def reflection
  @reflection
end

#tablesObject

Returns the value of attribute tables


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

def tables
  @tables
end

Instance Method Details

#aliased_table_nameObject


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# File 'lib/active_record/associations/join_dependency/join_association.rb', line 107

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
  klass         # => Physician
  table         # => #<Arel::Table @name="appointments" ...>
  key           # =>  physician_id
  foreign_table # => #<Arel::Table @name="physicians" ...>
  foreign_key   # => id

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# File 'lib/active_record/associations/join_dependency/join_association.rb', line 90

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, join_type, tables, chain) ⇒ Object


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# File 'lib/active_record/associations/join_dependency/join_association.rb', line 26

def join_constraints(foreign_table, foreign_klass, join_type, tables, chain)
  joins         = []
  binds         = []
  tables        = tables.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

    join_keys   = reflection.join_keys
    key         = join_keys.key
    foreign_key = join_keys.foreign_key

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

    predicate_builder = PredicateBuilder.new(TableMetadata.new(klass, table))
    scope_chain_items = reflection.join_scopes(table, predicate_builder)
    klass_scope       = reflection.klass_join_scope(table, predicate_builder)

    scope_chain_items.concat [klass_scope].compact

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

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

    if reflection.type
      value = foreign_klass.base_class.name
      column = klass.columns_hash[reflection.type.to_s]

      binds << Relation::QueryAttribute.new(column.name, value, klass.type_for_attribute(column.name))
      constraint = constraint.and klass.arel_attribute(reflection.type, table).eq(Arel::Nodes::BindParam.new)
    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

  JoinInformation.new joins, binds
end

#match?(other) ⇒ Boolean

Returns:

  • (Boolean)

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

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

#tableObject


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# File 'lib/active_record/associations/join_dependency/join_association.rb', line 103

def table
  tables.first
end