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require 'active_support/core_ext/array/wrap'
require 'active_support/core_ext/object/blank'
module ActiveRecord
module QueryMethods
extend ActiveSupport::Concern
attr_accessor :includes_values, :eager_load_values, :preload_values,
:select_values, :group_values, :order_values, :joins_values,
:where_values, :having_values, :bind_values,
:limit_value, :offset_value, :lock_value, :readonly_value, :create_with_value,
:from_value, :reordering_value, :reverse_order_value,
:uniq_value, :references_values
def includes(*args)
args.reject! {|a| a.blank? }
return self if args.empty?
relation = clone
relation.includes_values = (relation.includes_values + args).flatten.uniq
relation
end
def eager_load(*args)
return self if args.blank?
relation = clone
relation.eager_load_values += args
relation
end
def preload(*args)
return self if args.blank?
relation = clone
relation.preload_values += args
relation
end
# Used to indicate that an association is referenced by an SQL string, and should
# therefore be JOINed in any query rather than loaded separately.
#
# For example:
#
# User.includes(:posts).where("posts.name = 'foo'")
# # => Doesn't JOIN the posts table, resulting in an error.
#
# User.includes(:posts).where("posts.name = 'foo'").references(:posts)
# # => Query now knows the string references posts, so adds a JOIN
def references(*args)
return self if args.blank?
relation = clone
relation.references_values = (references_values + args.flatten.map(&:to_s)).uniq
relation
end
# Works in two unique ways.
#
# First: takes a block so it can be used just like Array#select.
#
# Model.scoped.select { |m| m.field == value }
#
# This will build an array of objects from the database for the scope,
# converting them into an array and iterating through them using Array#select.
#
# Second: Modifies the SELECT statement for the query so that only certain
# fields are retrieved:
#
# >> Model.select(:field)
# => [#<Model field:value>]
#
# Although in the above example it looks as though this method returns an
# array, it actually returns a relation object and can have other query
# methods appended to it, such as the other methods in ActiveRecord::QueryMethods.
#
# The argument to the method can also be an array of fields.
#
# >> Model.select([:field, :other_field, :and_one_more])
# => [#<Model field: "value", other_field: "value", and_one_more: "value">]
#
# Accessing attributes of an object that do not have fields retrieved by a select
# will throw <tt>ActiveModel::MissingAttributeError</tt>:
#
# >> Model.select(:field).first.other_field
# => ActiveModel::MissingAttributeError: missing attribute: other_field
def select(value = Proc.new)
if block_given?
to_a.select {|*block_args| value.call(*block_args) }
else
relation = clone
relation.select_values += Array.wrap(value)
relation
end
end
def group(*args)
return self if args.blank?
relation = clone
relation.group_values += args.flatten
relation
end
def order(*args)
return self if args.blank?
args = args.flatten
references = args.reject { |arg| Arel::Node === arg }
.map { |arg| arg =~ /^([a-zA-Z]\w*)\.(\w+)/ && $1 }
.compact
relation = clone
relation = relation.references(references) if references.any?
relation.order_values += args
relation
end
# Replaces any existing order defined on the relation with the specified order.
#
# User.order('email DESC').reorder('id ASC') # generated SQL has 'ORDER BY id ASC'
#
# Subsequent calls to order on the same relation will be appended. For example:
#
# User.order('email DESC').reorder('id ASC').order('name ASC')
#
# generates a query with 'ORDER BY id ASC, name ASC'.
#
def reorder(*args)
return self if args.blank?
relation = clone
relation.reordering_value = true
relation.order_values = args.flatten
relation
end
def joins(*args)
return self if args.compact.blank?
relation = clone
args.flatten!
relation.joins_values += args
relation
end
def bind(value)
relation = clone
relation.bind_values += [value]
relation
end
def where(opts, *rest)
return self if opts.blank?
relation = clone
relation = relation.references(PredicateBuilder.references(opts)) if Hash === opts
relation.where_values += build_where(opts, rest)
relation
end
def having(opts, *rest)
return self if opts.blank?
relation = clone
relation = relation.references(PredicateBuilder.references(opts)) if Hash === opts
relation.having_values += build_where(opts, rest)
relation
end
def limit(value)
relation = clone
relation.limit_value = value
relation
end
def offset(value)
relation = clone
relation.offset_value = value
relation
end
def lock(locks = true)
relation = clone
case locks
when String, TrueClass, NilClass
relation.lock_value = locks || true
else
relation.lock_value = false
end
relation
end
# Returns a chainable relation with zero records, specifically an
# instance of the NullRelation class.
#
# The returned NullRelation inherits from Relation and implements the
# Null Object pattern so it is an object with defined null behavior:
# it always returns an empty array of records and does not query the database.
#
# Any subsequent condition chained to the returned relation will continue
# generating an empty relation and will not fire any query to the database.
#
# Used in cases where a method or scope could return zero records but the
# result needs to be chainable.
#
# For example:
#
# @posts = current_user.visible_posts.where(:name => params[:name])
# # => the visible_posts method is expected to return a chainable Relation
#
# def visible_posts
# case role
# when 'Country Manager'
# Post.where(:country => country)
# when 'Reviewer'
# Post.published
# when 'Bad User'
# Post.none # => returning [] instead breaks the previous code
# end
# end
#
def none
NullRelation.new(@klass, @table)
end
def readonly(value = true)
relation = clone
relation.readonly_value = value
relation
end
def create_with(value)
relation = clone
relation.create_with_value = value ? create_with_value.merge(value) : {}
relation
end
def from(value)
relation = clone
relation.from_value = value
relation
end
# Specifies whether the records should be unique or not. For example:
#
# User.select(:name)
# # => Might return two records with the same name
#
# User.select(:name).uniq
# # => Returns 1 record per unique name
#
# User.select(:name).uniq.uniq(false)
# # => You can also remove the uniqueness
def uniq(value = true)
relation = clone
relation.uniq_value = value
relation
end
# Used to extend a scope with additional methods, either through
# a module or through a block provided.
#
# The object returned is a relation, which can be further extended.
#
# === Using a module
#
# module Pagination
# def page(number)
# # pagination code goes here
# end
# end
#
# scope = Model.scoped.extending(Pagination)
# scope.page(params[:page])
#
# You can also pass a list of modules:
#
# scope = Model.scoped.extending(Pagination, SomethingElse)
#
# === Using a block
#
# scope = Model.scoped.extending do
# def page(number)
# # pagination code goes here
# end
# end
# scope.page(params[:page])
#
# You can also use a block and a module list:
#
# scope = Model.scoped.extending(Pagination) do
# def per_page(number)
# # pagination code goes here
# end
# end
def extending(*modules)
modules << Module.new(&Proc.new) if block_given?
return self if modules.empty?
relation = clone
relation.send(:apply_modules, modules.flatten)
relation
end
def reverse_order
relation = clone
relation.reverse_order_value = !relation.reverse_order_value
relation
end
def arel
@arel ||= with_default_scope.build_arel
end
def build_arel
arel = table.from table
build_joins(arel, @joins_values) unless @joins_values.empty?
collapse_wheres(arel, (@where_values - ['']).uniq)
arel.having(*@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(*@group_values.uniq.reject{|g| g.blank?}) unless @group_values.empty?
order = @order_values
order = reverse_sql_order(order) if @reverse_order_value
arel.order(*order.uniq.reject{|o| o.blank?}) unless order.empty?
build_select(arel, @select_values.uniq)
arel.distinct(@uniq_value)
arel.from(@from_value) if @from_value
arel.lock(@lock_value) if @lock_value
arel
end
private
def custom_join_ast(table, joins)
joins = joins.reject { |join| join.blank? }
return [] if joins.empty?
@implicit_readonly = true
joins.map do |join|
case join
when Array
join = Arel.sql(join.join(' ')) if array_of_strings?(join)
when String
join = Arel.sql(join)
end
table.create_string_join(join)
end
end
def collapse_wheres(arel, wheres)
equalities = wheres.grep(Arel::Nodes::Equality)
arel.where(Arel::Nodes::And.new(equalities)) unless equalities.empty?
(wheres - equalities).each do |where|
where = Arel.sql(where) if String === where
arel.where(Arel::Nodes::Grouping.new(where))
end
end
def build_where(opts, other = [])
case opts
when String, Array
[@klass.send(:sanitize_sql, other.empty? ? opts : ([opts] + other))]
when Hash
attributes = @klass.send(:expand_hash_conditions_for_aggregates, opts)
PredicateBuilder.build_from_hash(table.engine, attributes, table)
else
[opts]
end
end
def build_joins(manager, joins)
buckets = joins.group_by do |join|
case join
when String
'string_join'
when Hash, Symbol, Array
'association_join'
when ActiveRecord::Associations::JoinDependency::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'] || []).uniq
string_joins = (buckets['string_join'] || []).map { |x|
x.strip
}.uniq
join_list = join_nodes + custom_join_ast(manager, string_joins)
join_dependency = ActiveRecord::Associations::JoinDependency.new(
@klass,
association_joins,
join_list
)
join_dependency.graft(*stashed_association_joins)
@implicit_readonly = true unless association_joins.empty? && stashed_association_joins.empty?
# FIXME: refactor this to build an AST
join_dependency.join_associations.each do |association|
association.join_to(manager)
end
manager.join_sources.concat join_list
manager
end
def build_select(arel, selects)
unless selects.empty?
@implicit_readonly = false
arel.project(*selects)
else
arel.project(@klass.arel_table[Arel.star])
end
end
def apply_modules(modules)
unless modules.empty?
@extensions += modules
modules.each {|extension| extend(extension) }
end
end
def reverse_sql_order(order_query)
order_query = ["#{quoted_table_name}.#{quoted_primary_key} ASC"] if order_query.empty?
order_query.map do |o|
case o
when Arel::Nodes::Ordering
o.reverse
when String, Symbol
o.to_s.split(',').collect do |s|
s.strip!
s.gsub!(/\sasc\Z/i, ' DESC') || s.gsub!(/\sdesc\Z/i, ' ASC') || s.concat(' DESC')
end
else
o
end
end.flatten
end
def array_of_strings?(o)
o.is_a?(Array) && o.all?{|obj| obj.is_a?(String)}
end
end
end
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