# -*- coding: utf-8 -*-
require 'active_support/core_ext/object/blank'
module ActiveRecord
# = Active Record Relation
class Relation
JoinOperation = Struct.new(:relation, :join_class, :on)
ASSOCIATION_METHODS = [:includes, :eager_load, :preload]
MULTI_VALUE_METHODS = [:select, :group, :order, :joins, :where, :having, :bind]
SINGLE_VALUE_METHODS = [:limit, :offset, :lock, :readonly, :from, :reordering, :reverse_order, :uniq]
include FinderMethods, Calculations, SpawnMethods, QueryMethods, Batches, Explain, Delegation
attr_reader :table, :klass, :loaded
attr_accessor :extensions, :default_scoped
alias :loaded? :loaded
alias :default_scoped? :default_scoped
def initialize(klass, table)
@klass, @table = klass, table
@implicit_readonly = nil
@loaded = false
@default_scoped = false
SINGLE_VALUE_METHODS.each {|v| instance_variable_set(:"@#{v}_value", nil)}
(ASSOCIATION_METHODS + MULTI_VALUE_METHODS).each {|v| instance_variable_set(:"@#{v}_values", [])}
@extensions = []
@create_with_value = {}
end
def insert(values)
primary_key_value = nil
if primary_key && Hash === values
primary_key_value = values[values.keys.find { |k|
k.name == primary_key
}]
if !primary_key_value && connection.prefetch_primary_key?(klass.table_name)
primary_key_value = connection.next_sequence_value(klass.sequence_name)
values[klass.arel_table[klass.primary_key]] = primary_key_value
end
end
im = arel.create_insert
im.into @table
conn = @klass.connection
substitutes = values.sort_by { |arel_attr,_| arel_attr.name }
binds = substitutes.map do |arel_attr, value|
[@klass.columns_hash[arel_attr.name], value]
end
substitutes.each_with_index do |tuple, i|
tuple[1] = conn.substitute_at(binds[i][0], i)
end
if values.empty? # empty insert
im.values = Arel.sql(connection.empty_insert_statement_value)
else
im.insert substitutes
end
conn.insert(
im,
'SQL',
primary_key,
primary_key_value,
nil,
binds)
end
def new(*args, &block)
scoping { @klass.new(*args, &block) }
end
def initialize_copy(other)
reset
end
alias build new
def create(*args, &block)
scoping { @klass.create(*args, &block) }
end
def create!(*args, &block)
scoping { @klass.create!(*args, &block) }
end
# Tries to load the first record; if it fails, then create is called with the same arguments as this method.
#
# Expects arguments in the same format as Base.create.
#
# ==== Examples
# # Find the first user named Penélope or create a new one.
# User.where(:first_name => 'Penélope').first_or_create
# # =>
#
# # Find the first user named Penélope or create a new one.
# # We already have one so the existing record will be returned.
# User.where(:first_name => 'Penélope').first_or_create
# # =>
#
# # Find the first user named Scarlett or create a new one with a particular last name.
# User.where(:first_name => 'Scarlett').first_or_create(:last_name => 'Johansson')
# # =>
#
# # Find the first user named Scarlett or create a new one with a different last name.
# # We already have one so the existing record will be returned.
# User.where(:first_name => 'Scarlett').first_or_create do |user|
# user.last_name = "O'Hara"
# end
# # =>
def first_or_create(attributes = nil, options = {}, &block)
first || create(attributes, options, &block)
end
# Like first_or_create but calls create! so an exception is raised if the created record is invalid.
#
# Expects arguments in the same format as Base.create!.
def first_or_create!(attributes = nil, options = {}, &block)
first || create!(attributes, options, &block)
end
# Like first_or_create but calls new instead of create.
#
# Expects arguments in the same format as Base.new.
def first_or_initialize(attributes = nil, options = {}, &block)
first || new(attributes, options, &block)
end
# Runs EXPLAIN on the query or queries triggered by this relation and
# returns the result as a string. The string is formatted imitating the
# ones printed by the database shell.
#
# Note that this method actually runs the queries, since the results of some
# are needed by the next ones when eager loading is going on.
#
# Please see further details in the
# {Active Record Query Interface guide}[http://edgeguides.rubyonrails.org/active_record_querying.html#running-explain].
def explain
_, queries = collecting_queries_for_explain { exec_queries }
exec_explain(queries)
end
def to_a
# We monitor here the entire execution rather than individual SELECTs
# because from the point of view of the user fetching the records of a
# relation is a single unit of work. You want to know if this call takes
# too long, not if the individual queries take too long.
#
# It could be the case that none of the queries involved surpass the
# threshold, and at the same time the sum of them all does. The user
# should get a query plan logged in that case.
logging_query_plan do
exec_queries
end
end
def exec_queries
return @records if loaded?
default_scoped = with_default_scope
if default_scoped.equal?(self)
@records = if @readonly_value.nil? && !@klass.locking_enabled?
eager_loading? ? find_with_associations : @klass.find_by_sql(arel, @bind_values)
else
IdentityMap.without do
eager_loading? ? find_with_associations : @klass.find_by_sql(arel, @bind_values)
end
end
preload = @preload_values
preload += @includes_values unless eager_loading?
preload.each do |associations|
ActiveRecord::Associations::Preloader.new(@records, associations).run
end
# @readonly_value is true only if set explicitly. @implicit_readonly is true if there
# are JOINS and no explicit SELECT.
readonly = @readonly_value.nil? ? @implicit_readonly : @readonly_value
@records.each { |record| record.readonly! } if readonly
else
@records = default_scoped.to_a
end
@loaded = true
@records
end
private :exec_queries
def as_json(options = nil) #:nodoc:
to_a.as_json(options)
end
# Returns size of the records.
def size
loaded? ? @records.length : count
end
# Returns true if there are no records.
def empty?
return @records.empty? if loaded?
c = count
c.respond_to?(:zero?) ? c.zero? : c.empty?
end
def any?
if block_given?
to_a.any? { |*block_args| yield(*block_args) }
else
!empty?
end
end
def many?
if block_given?
to_a.many? { |*block_args| yield(*block_args) }
else
@limit_value ? to_a.many? : size > 1
end
end
# Scope all queries to the current scope.
#
# ==== Example
#
# Comment.where(:post_id => 1).scoping do
# Comment.first # SELECT * FROM comments WHERE post_id = 1
# end
#
# Please check unscoped if you want to remove all previous scopes (including
# the default_scope) during the execution of a block.
def scoping
@klass.with_scope(self, :overwrite) { yield }
end
# Updates all records with details given if they match a set of conditions supplied, limits and order can
# also be supplied. This method constructs a single SQL UPDATE statement and sends it straight to the
# database. It does not instantiate the involved models and it does not trigger Active Record callbacks
# or validations.
#
# ==== Parameters
#
# * +updates+ - A string, array, or hash representing the SET part of an SQL statement.
# * +conditions+ - A string, array, or hash representing the WHERE part of an SQL statement.
# See conditions in the intro.
# * +options+ - Additional options are :limit and :order, see the examples for usage.
#
# ==== Examples
#
# # Update all customers with the given attributes
# Customer.update_all :wants_email => true
#
# # Update all books with 'Rails' in their title
# Book.update_all "author = 'David'", "title LIKE '%Rails%'"
#
# # Update all avatars migrated more than a week ago
# Avatar.update_all ['migrated_at = ?', Time.now.utc], ['migrated_at > ?', 1.week.ago]
#
# # Update all books that match conditions, but limit it to 5 ordered by date
# Book.update_all "author = 'David'", "title LIKE '%Rails%'", :order => 'created_at', :limit => 5
#
# # Conditions from the current relation also works
# Book.where('title LIKE ?', '%Rails%').update_all(:author => 'David')
#
# # The same idea applies to limit and order
# Book.where('title LIKE ?', '%Rails%').order(:created_at).limit(5).update_all(:author => 'David')
def update_all(updates, conditions = nil, options = {})
IdentityMap.repository[symbolized_base_class].clear if IdentityMap.enabled?
if conditions || options.present?
where(conditions).apply_finder_options(options.slice(:limit, :order)).update_all(updates)
else
stmt = Arel::UpdateManager.new(arel.engine)
stmt.set Arel.sql(@klass.send(:sanitize_sql_for_assignment, updates))
stmt.table(table)
stmt.key = table[primary_key]
if joins_values.any?
@klass.connection.join_to_update(stmt, arel)
else
stmt.take(arel.limit)
stmt.order(*arel.orders)
stmt.wheres = arel.constraints
end
@klass.connection.update stmt, 'SQL', bind_values
end
end
# Updates an object (or multiple objects) and saves it to the database, if validations pass.
# The resulting object is returned whether the object was saved successfully to the database or not.
#
# ==== Parameters
#
# * +id+ - This should be the id or an array of ids to be updated.
# * +attributes+ - This should be a hash of attributes or an array of hashes.
#
# ==== Examples
#
# # Updates one record
# Person.update(15, :user_name => 'Samuel', :group => 'expert')
#
# # Updates multiple records
# people = { 1 => { "first_name" => "David" }, 2 => { "first_name" => "Jeremy" } }
# Person.update(people.keys, people.values)
def update(id, attributes)
if id.is_a?(Array)
id.each.with_index.map {|one_id, idx| update(one_id, attributes[idx])}
else
object = find(id)
object.update_attributes(attributes)
object
end
end
# Destroys the records matching +conditions+ by instantiating each
# record and calling its +destroy+ method. Each object's callbacks are
# executed (including :dependent association options and
# +before_destroy+/+after_destroy+ Observer methods). Returns the
# collection of objects that were destroyed; each will be frozen, to
# reflect that no changes should be made (since they can't be
# persisted).
#
# Note: Instantiation, callback execution, and deletion of each
# record can be time consuming when you're removing many records at
# once. It generates at least one SQL +DELETE+ query per record (or
# possibly more, to enforce your callbacks). If you want to delete many
# rows quickly, without concern for their associations or callbacks, use
# +delete_all+ instead.
#
# ==== Parameters
#
# * +conditions+ - A string, array, or hash that specifies which records
# to destroy. If omitted, all records are destroyed. See the
# Conditions section in the introduction to ActiveRecord::Base for
# more information.
#
# ==== Examples
#
# Person.destroy_all("last_login < '2004-04-04'")
# Person.destroy_all(:status => "inactive")
# Person.where(:age => 0..18).destroy_all
def destroy_all(conditions = nil)
if conditions
where(conditions).destroy_all
else
to_a.each {|object| object.destroy }.tap { reset }
end
end
# Destroy an object (or multiple objects) that has the given id. The object is instantiated first,
# therefore all callbacks and filters are fired off before the object is deleted. This method is
# less efficient than ActiveRecord#delete but allows cleanup methods and other actions to be run.
#
# This essentially finds the object (or multiple objects) with the given id, creates a new object
# from the attributes, and then calls destroy on it.
#
# ==== Parameters
#
# * +id+ - Can be either an Integer or an Array of Integers.
#
# ==== Examples
#
# # Destroy a single object
# Todo.destroy(1)
#
# # Destroy multiple objects
# todos = [1,2,3]
# Todo.destroy(todos)
def destroy(id)
if id.is_a?(Array)
id.map { |one_id| destroy(one_id) }
else
find(id).destroy
end
end
# Deletes the records matching +conditions+ without instantiating the records first, and hence not
# calling the +destroy+ method nor invoking callbacks. This is a single SQL DELETE statement that
# goes straight to the database, much more efficient than +destroy_all+. Be careful with relations
# though, in particular :dependent rules defined on associations are not honored. Returns
# the number of rows affected.
#
# ==== Parameters
#
# * +conditions+ - Conditions are specified the same way as with +find+ method.
#
# ==== Example
#
# Post.delete_all("person_id = 5 AND (category = 'Something' OR category = 'Else')")
# Post.delete_all(["person_id = ? AND (category = ? OR category = ?)", 5, 'Something', 'Else'])
# Post.where(:person_id => 5).where(:category => ['Something', 'Else']).delete_all
#
# Both calls delete the affected posts all at once with a single DELETE statement.
# If you need to destroy dependent associations or call your before_* or
# +after_destroy+ callbacks, use the +destroy_all+ method instead.
def delete_all(conditions = nil)
IdentityMap.repository[symbolized_base_class] = {} if IdentityMap.enabled?
if conditions
where(conditions).delete_all
else
statement = arel.compile_delete
affected = @klass.connection.delete(statement, 'SQL', bind_values)
reset
affected
end
end
# Deletes the row with a primary key matching the +id+ argument, using a
# SQL +DELETE+ statement, and returns the number of rows deleted. Active
# Record objects are not instantiated, so the object's callbacks are not
# executed, including any :dependent association options or
# Observer methods.
#
# You can delete multiple rows at once by passing an Array of ids.
#
# Note: Although it is often much faster than the alternative,
# #destroy, skipping callbacks might bypass business logic in
# your application that ensures referential integrity or performs other
# essential jobs.
#
# ==== Examples
#
# # Delete a single row
# Todo.delete(1)
#
# # Delete multiple rows
# Todo.delete([2,3,4])
def delete(id_or_array)
IdentityMap.remove_by_id(self.symbolized_base_class, id_or_array) if IdentityMap.enabled?
where(primary_key => id_or_array).delete_all
end
def reload
reset
to_a # force reload
self
end
def reset
@first = @last = @to_sql = @order_clause = @scope_for_create = @arel = @loaded = nil
@should_eager_load = @join_dependency = nil
@records = []
self
end
def to_sql
@to_sql ||= klass.connection.to_sql(arel)
end
def where_values_hash
equalities = with_default_scope.where_values.grep(Arel::Nodes::Equality).find_all { |node|
node.left.relation.name == table_name
}
Hash[equalities.map { |where| [where.left.name, where.right] }]
end
def scope_for_create
@scope_for_create ||= where_values_hash.merge(create_with_value)
end
def eager_loading?
@should_eager_load ||=
@eager_load_values.any? ||
@includes_values.any? && (joined_includes_values.any? || references_eager_loaded_tables?)
end
# Joins that are also marked for preloading. In which case we should just eager load them.
# Note that this is a naive implementation because we could have strings and symbols which
# represent the same association, but that aren't matched by this. Also, we could have
# nested hashes which partially match, e.g. { :a => :b } & { :a => [:b, :c] }
def joined_includes_values
@includes_values & @joins_values
end
def ==(other)
case other
when Relation
other.to_sql == to_sql
when Array
to_a == other
end
end
def inspect
to_a.inspect
end
def with_default_scope #:nodoc:
if default_scoped? && default_scope = klass.send(:build_default_scope)
default_scope = default_scope.merge(self)
default_scope.default_scoped = false
default_scope
else
self
end
end
private
def references_eager_loaded_tables?
joined_tables = arel.join_sources.map do |join|
if join.is_a?(Arel::Nodes::StringJoin)
tables_in_string(join.left)
else
[join.left.table_name, join.left.table_alias]
end
end
joined_tables += [table.name, table.table_alias]
# always convert table names to downcase as in Oracle quoted table names are in uppercase
joined_tables = joined_tables.flatten.compact.map { |t| t.downcase }.uniq
(tables_in_string(to_sql) - joined_tables).any?
end
def tables_in_string(string)
return [] if string.blank?
# always convert table names to downcase as in Oracle quoted table names are in uppercase
# ignore raw_sql_ that is used by Oracle adapter as alias for limit/offset subqueries
string.scan(/([a-zA-Z_][.\w]+).?\./).flatten.map{ |s| s.downcase }.uniq - ['raw_sql_']
end
end
end