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,
lib/squeel/adapters/active_record/3.1/relation_extensions.rb

Constant Summary collapse

JoinAssociation = 
::ActiveRecord::Associations::JoinDependency::JoinAssociation
JoinDependency = 
::ActiveRecord::Associations::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/3.0/relation_extensions.rb', line 19

def join_dependency
  @join_dependency ||= (build_join_dependency(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/3.0/relation_extensions.rb', line 334

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/3.0/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/3.1/relation_extensions.rb', line 105

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 8

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

  arel
end

#build_join_dependency(manager, joins) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/3.0/relation_extensions.rb', line 119

def build_join_dependency(relation, joins)
  association_joins = []

  joins = joins.map {|j| j.respond_to?(:strip) ? j.strip : j}.uniq

  joins.each do |join|
    association_joins << join if [Hash, Array, Symbol, Nodes::Stub, Nodes::Join, Nodes::KeyPath].include?(join.class) && !array_of_strings?(join)
  end

  stashed_association_joins = joins.grep(::ActiveRecord::Associations::ClassMethods::JoinDependency::JoinAssociation)

  non_association_joins = (joins - association_joins - stashed_association_joins)
  custom_joins = custom_join_sql(*non_association_joins)

  self.join_dependency = JoinDependency.new(@klass, association_joins, custom_joins)

  join_dependency.graft(*stashed_association_joins)

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

  to_join = []

  join_dependency.join_associations.each do |association|
    if (association_relation = association.relation).is_a?(Array)
      to_join << [association_relation.first, association.join_type, association.association_join.first]
      to_join << [association_relation.last, association.join_type, association.association_join.last]
    else
      to_join << [association_relation, association.join_type, association.association_join]
    end
  end

  to_join.uniq.each do |left, join_type, right|
    relation = relation.join(left, join_type).on(*right)
  end

  relation = relation.join(custom_joins)
end

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



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# File 'lib/squeel/adapters/active_record/3.0/relation_extensions.rb', line 243

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/3.0/relation_extensions.rb', line 261

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

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

  groups.each do |_, bins|
    arel = arel.where(bins.inject(&:and))
  end

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

  arel
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/3.0/relation_extensions.rb', line 298

def debug_sql
  if eager_loading?
    including = (@eager_load_values + @includes_values).uniq
    join_dependency = JoinDependency.new(@klass, including, nil)
    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/3.0/relation_extensions.rb', line 173

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/3.0/relation_extensions.rb', line 279

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/3.0/relation_extensions.rb', line 195

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/3.0/relation_extensions.rb', line 235

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/3.0/relation_extensions.rb', line 157

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/3.0/relation_extensions.rb', line 219

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

#merge(r, relations_visited = false) ⇒ Object

We need to be able to support merging two relations without having to get our hooks too deeply into ActiveRecord. AR’s relation merge functionality is very cool, but relatively complex, to handle the various edge cases. Our best shot at avoiding strange behavior with Squeel loaded is to visit the *_values arrays in the relations we’re merging, and then use the default AR merge code on the result.



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# File 'lib/squeel/adapters/active_record/3.0/relation_extensions.rb', line 42

def merge(r, relations_visited = false)
  if relations_visited
    super(r)
  else
    clone.visit!.merge(r.clone.visit!, true)
  end
end

#order(*args) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/3.0/relation_extensions.rb', line 203

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/3.0/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/3.0/relation_extensions.rb', line 165

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/3.1/relation_extensions.rb', line 50

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

#reorder(*args) ⇒ Object 



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# File 'lib/squeel/adapters/active_record/3.0/relation_extensions.rb', line 211

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/3.0/relation_extensions.rb', line 181

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

#select_for_count ⇒ Object

So, building a select for a count query in ActiveRecord is pretty heavily dependent on select_values containing strings. I’d initially expected that I could just hack together a fix to select_for_count and everything would fall in line, but unfortunately, pretty much everything from that point on in ActiveRecord::Calculations#perform_calculation expects the column to be a string, or at worst, a symbol.

In the long term, I would like to refactor the code in Rails core, but for now, I’m going to settle for this hack that tries really hard to coerce things to a string.



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# File 'lib/squeel/adapters/active_record/3.0/relation_extensions.rb', line 101

def select_for_count
  visited_values = attribute_visitor.accept(select_values.uniq)
  if visited_values.size == 1
    select = visited_values.first

    str_select = case select
    when String
      select
    when Symbol
      select.to_s
    else
      select.to_sql if select.respond_to?(:to_sql)
    end

    str_select if str_select && str_select !~ /[,*]/
  end
end

#visit! ⇒ Object 



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# File 'lib/squeel/adapters/active_record/3.0/relation_extensions.rb', line 50

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/3.0/relation_extensions.rb', line 227

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/3.0/relation_extensions.rb', line 340

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