Module: Squeel::Adapters::ActiveRecord::RelationExtensions

Defined in:
lib/squeel/adapters/active_record/relation_extensions.rb,
lib/squeel/adapters/active_record/3.0/relation_extensions.rb

Constant Summary collapse

JoinAssociation = 
::ActiveRecord::Associations::ClassMethods::JoinDependency::JoinAssociation
JoinDependency = 
::ActiveRecord::Associations::ClassMethods::JoinDependency

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Instance Attribute Details

#join_dependency ⇒ Object

Returns a JoinDependency for the current relation.

We don’t need to clear out @join_dependency by overriding #reset, because the default #reset already does this, despite never setting it anywhere that I can find. Serendipity, I say!



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 19

def join_dependency
  @join_dependency ||= (build_join_dependency(table.from(table), @joins_values) && @join_dependency)
end

Class Method Details

.included(base) ⇒ Object

ZOMG ALIAS_METHOD_CHAIN IS BELOW. HIDE YOUR EYES! … … … Since you’re still looking, let me explain this horrible transgression you see before you. You see, Relation#where_values_hash is defined on the ActiveRecord::Relation class. Since it’s defined there, but I would very much like to modify its behavior, I have three choices.

  1. Inherit from ActiveRecord::Relation in a Squeel::Relation class, and make an attempt to usurp all of the various calls to methods on ActiveRecord::Relation by doing some really evil stuff with constant reassignment, all for the sake of being able to use super().

  2. Submit a patch to Rails core, breaking this method off into another module, all for my own selfish desire to use super() while mucking about in Rails internals.

  3. Use alias_method_chain, and say 10 hail Hanssons as penance.

I opted to go with #3. Except for the hail Hansson thing. Unless you’re DHH, in which case, I totally said them.



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 345

def self.included(base)
  base.class_eval do
    alias_method_chain :where_values_hash, :squeel
  end
end

Instance Method Details

#attribute_visitor ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 29

def attribute_visitor
  Visitors::AttributeVisitor.new(
    Context.new(join_dependency)
  )
end

#attrs_to_orderings(order) ⇒ Object

reverse_sql_order will reverse the order of strings or Orderings, but not attributes



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 114

def attrs_to_orderings(order)
  order.map do |o|
    Arel::Attribute === o ? o.asc : o
  end
end

#build_arel ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 82

def build_arel
  arel = table.from table

  build_join_dependency(arel, @joins_values) unless @joins_values.empty?

  predicate_viz = predicate_visitor
  attribute_viz = attribute_visitor

  collapse_wheres(arel, predicate_viz.accept((@where_values - ['']).uniq))

  arel.having(*predicate_viz.accept(@having_values.uniq.reject{|h| h.blank?})) unless @having_values.empty?

  arel.take(connection.sanitize_limit(@limit_value)) if @limit_value
  arel.skip(@offset_value) if @offset_value

  arel.group(*attribute_viz.accept(@group_values.uniq.reject{|g| g.blank?})) unless @group_values.empty?

  order = @reorder_value ? @reorder_value : @order_values
  order = attribute_viz.accept(order.uniq.reject{|o| o.blank?})
  order = reverse_sql_order(attrs_to_orderings(order)) if @reverse_order_value
  arel.order(*order) unless order.empty?

  build_select(arel, attribute_viz.accept(@select_values.uniq))

  arel.from(@from_value) if @from_value
  arel.lock(@lock_value) if @lock_value

  arel
end

#build_join_dependency(relation, joins) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 120

def build_join_dependency(manager, joins)
  buckets = joins.group_by do |join|
    case join
    when String
      'string_join'
    when Hash, Symbol, Array, Nodes::Stub, Nodes::Join, Nodes::KeyPath
      'association_join'
    when JoinAssociation
      'stashed_join'
    when Arel::Nodes::Join
      'join_node'
    else
      raise 'unknown class: %s' % join.class.name
    end
  end

  association_joins         = buckets['association_join'] || []
  stashed_association_joins = buckets['stashed_join'] || []
  join_nodes                = buckets['join_node'] || []
  string_joins              = (buckets['string_join'] || []).map { |x|
    x.strip
  }.uniq

  join_list = custom_join_ast(manager, string_joins)

  # All of this duplication just to add
  self.join_dependency = JoinDependency.new(
    @klass,
    association_joins,
    join_list
  )

  join_nodes.each do |join|
    join_dependency.alias_tracker.aliased_name_for(join.left.name.downcase)
  end

  join_dependency.graft(*stashed_association_joins)

  @implicit_readonly = true unless association_joins.empty? && stashed_association_joins.empty?

  join_dependency.join_associations.each do |association|
    association.join_to(manager)
  end

  manager.join_sources.concat join_nodes.uniq
  manager.join_sources.concat join_list

  manager
end

#build_where(opts, other = []) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 256

def build_where(opts, other = [])
  case opts
  when String, Array
    super
  else  # Let's prevent PredicateBuilder from doing its thing
    [opts, *other].map do |arg|
      case arg
      when Array  # Just in case there's an array in there somewhere
        @klass.send(:sanitize_sql, arg)
      when Hash
        @klass.send(:expand_hash_conditions_for_aggregates, arg)
      else
        arg
      end
    end
  end
end

#collapse_wheres(arel, wheres) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 274

def collapse_wheres(arel, wheres)
  wheres = Array(wheres)
  binaries = wheres.grep(Arel::Nodes::Binary)

  groups = binaries.group_by {|b| [b.class, b.left]}

  groups.each do |_, bins|
    arel.where(Arel::Nodes::And.new(bins))
  end

  (wheres - binaries).each do |where|
    where = Arel.sql(where) if String === where
    arel.where(Arel::Nodes::Grouping.new(where))
  end
end

#debug_sql ⇒ Object

Simulate the logic that occurs in #to_a

This will let us get a dump of the SQL that will be run against the DB for debug purposes without actually running the query.



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 309

def debug_sql
  if eager_loading?
    including = (@eager_load_values + @includes_values).uniq
    join_dependency = JoinDependency.new(@klass, including, [])
    construct_relation_for_association_find(join_dependency).to_sql
  else
    arel.to_sql
  end
end

#eager_load(*args) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 186

def eager_load(*args)
  if block_given? && args.empty?
    super(DSL.eval &Proc.new)
  else
    super
  end
end

#find_equality_predicates(nodes) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 290

def find_equality_predicates(nodes)
  nodes.map { |node|
    case node
    when Arel::Nodes::Equality
      node if node.left.relation.name == table_name
    when Arel::Nodes::Grouping
      find_equality_predicates([node.expr])
    when Arel::Nodes::And
      find_equality_predicates(node.children)
    else
      nil
    end
  }.compact.flatten
end

#group(*args) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 208

def group(*args)
  if block_given? && args.empty?
    super(DSL.eval &Proc.new)
  else
    super
  end
end

#having(*args) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 248

def having(*args)
  if block_given? && args.empty?
    super(DSL.eval &Proc.new)
  else
    super
  end
end

#includes(*args) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 170

def includes(*args)
  if block_given? && args.empty?
    super(DSL.eval &Proc.new)
  else
    super
  end
end

#joins(*args) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 232

def joins(*args)
  if block_given? && args.empty?
    super(DSL.eval &Proc.new)
  else
    super
  end
end

#merge(r) ⇒ Object

We need to be able to support merging two relations that have a different base class. Stock ActiveRecord doesn’t have to do anything too special, because it’s already created predicates out of the where_values by now, and they’re already bound to the proper table.

Squeel, on the other hand, needs to do its best to ensure the predicates are still winding up against the proper table. The most “correct” way I can think of to do this is to try to emulate the default AR behavior – that is, de-squeelifying the *_values, erm… values by visiting them and converting them to ARel nodes before merging. Merging relations is a nifty little trick, but it’s another little corner of ActiveRecord where the magic quickly fades. :(



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 46

def merge(r)
  if relation_with_different_base?(r)
    r = r.clone.visit!
  end

  super(r)
end

#order(*args) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 216

def order(*args)
  if block_given? && args.empty?
    super(DSL.eval &Proc.new)
  else
    super
  end
end

#predicate_visitor ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 23

def predicate_visitor
  Visitors::PredicateVisitor.new(
    Context.new(join_dependency)
  )
end

#preload(*args) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 178

def preload(*args)
  if block_given? && args.empty?
    super(DSL.eval &Proc.new)
  else
    super
  end
end

#prepare_relation_for_association_merge!(r, association_name) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 59

def prepare_relation_for_association_merge!(r, association_name)
  r.where_values.map! {|w| Squeel::Visitors::PredicateVisitor.can_visit?(w) ? {association_name => w} : w}
  r.having_values.map! {|h| Squeel::Visitors::PredicateVisitor.can_visit?(h) ? {association_name => h} : h}
  r.group_values.map! {|g| Squeel::Visitors::AttributeVisitor.can_visit?(g) ? {association_name => g} : g}
  r.order_values.map! {|o| Squeel::Visitors::AttributeVisitor.can_visit?(o) ? {association_name => o} : o}
  r.select_values.map! {|s| Squeel::Visitors::AttributeVisitor.can_visit?(s) ? {association_name => s} : s}
  r.joins_values.map! {|j| [Symbol, Hash, Nodes::Stub, Nodes::Join, Nodes::KeyPath].include?(j.class) ? {association_name => j} : j}
  r.includes_values.map! {|i| [Symbol, Hash, Nodes::Stub, Nodes::Join, Nodes::KeyPath].include?(i.class) ? {association_name => i} : i}
end

#relation_with_different_base?(r) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 54

def relation_with_different_base?(r)
  ::ActiveRecord::Relation === r &&
  base_class.name != r.klass.base_class.name
end

#reorder(*args) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 224

def reorder(*args)
  if block_given? && args.empty?
    super(DSL.eval &Proc.new)
  else
    super
  end
end

#select(value = Proc.new) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 194

def select(value = Proc.new)
  if block_given? && Proc === value
    if value.arity > 0
      to_a.select {|*block_args| value.call(*block_args)}
    else
      relation = clone
      relation.select_values += Array.wrap(DSL.eval &value)
      relation
    end
  else
    super
  end
end

#visit! ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 69

def visit!
  predicate_viz = predicate_visitor
  attribute_viz = attribute_visitor

  @where_values = predicate_viz.accept((@where_values - ['']).uniq)
  @having_values = predicate_viz.accept(@having_values.uniq.reject{|h| h.blank?})
  @group_values = attribute_viz.accept(@group_values.uniq.reject{|g| g.blank?})
  @order_values = attribute_viz.accept(@order_values.uniq.reject{|o| o.blank?})
  @select_values = attribute_viz.accept(@select_values.uniq)

  self
end

#where(opts = Proc.new, *rest) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 240

def where(opts = Proc.new, *rest)
  if block_given? && Proc === opts
    super(DSL.eval &opts)
  else
    super
  end
end

#where_values_hash_with_squeel ⇒ Object 



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# File 'lib/squeel/adapters/active_record/relation_extensions.rb', line 351

def where_values_hash_with_squeel
  equalities = find_equality_predicates(predicate_visitor.accept(@where_values))

  Hash[equalities.map { |where| [where.left.name, where.right] }]
end