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require 'active_support/core_ext/object/blank'
require 'active_support/core_ext/hash/indifferent_access'
module ActiveRecord
module FinderMethods
# Find operates with four different retrieval approaches:
#
# * Find by id - This can either be a specific id (1), a list of ids (1, 5, 6), or an array of ids ([5, 6, 10]).
# If no record can be found for all of the listed ids, then RecordNotFound will be raised.
# * Find first - This will return the first record matched by the options used. These options can either be specific
# conditions or merely an order. If no record can be matched, +nil+ is returned. Use
# <tt>Model.find(:first, *args)</tt> or its shortcut <tt>Model.first(*args)</tt>.
# * Find last - This will return the last record matched by the options used. These options can either be specific
# conditions or merely an order. If no record can be matched, +nil+ is returned. Use
# <tt>Model.find(:last, *args)</tt> or its shortcut <tt>Model.last(*args)</tt>.
# * Find all - This will return all the records matched by the options used.
# If no records are found, an empty array is returned. Use
# <tt>Model.find(:all, *args)</tt> or its shortcut <tt>Model.all(*args)</tt>.
#
# All approaches accept an options hash as their last parameter.
#
# ==== Parameters
#
# * <tt>:conditions</tt> - An SQL fragment like "administrator = 1", <tt>[ "user_name = ?", username ]</tt>, or <tt>["user_name = :user_name", { :user_name => user_name }]</tt>. See conditions in the intro.
# * <tt>:order</tt> - An SQL fragment like "created_at DESC, name".
# * <tt>:group</tt> - An attribute name by which the result should be grouped. Uses the <tt>GROUP BY</tt> SQL-clause.
# * <tt>:having</tt> - Combined with +:group+ this can be used to filter the records that a <tt>GROUP BY</tt> returns. Uses the <tt>HAVING</tt> SQL-clause.
# * <tt>:limit</tt> - An integer determining the limit on the number of rows that should be returned.
# * <tt>:offset</tt> - An integer determining the offset from where the rows should be fetched. So at 5, it would skip rows 0 through 4.
# * <tt>:joins</tt> - Either an SQL fragment for additional joins like "LEFT JOIN comments ON comments.post_id = id" (rarely needed),
# named associations in the same form used for the <tt>:include</tt> option, which will perform an <tt>INNER JOIN</tt> on the associated table(s),
# or an array containing a mixture of both strings and named associations.
# If the value is a string, then the records will be returned read-only since they will have attributes that do not correspond to the table's columns.
# Pass <tt>:readonly => false</tt> to override.
# * <tt>:include</tt> - Names associations that should be loaded alongside. The symbols named refer
# to already defined associations. See eager loading under Associations.
# * <tt>:select</tt> - By default, this is "*" as in "SELECT * FROM", but can be changed if you, for example, want to do a join but not
# include the joined columns. Takes a string with the SELECT SQL fragment (e.g. "id, name").
# * <tt>:from</tt> - By default, this is the table name of the class, but can be changed to an alternate table name (or even the name
# of a database view).
# * <tt>:readonly</tt> - Mark the returned records read-only so they cannot be saved or updated.
# * <tt>:lock</tt> - An SQL fragment like "FOR UPDATE" or "LOCK IN SHARE MODE".
# <tt>:lock => true</tt> gives connection's default exclusive lock, usually "FOR UPDATE".
#
# ==== Examples
#
# # find by id
# Person.find(1) # returns the object for ID = 1
# Person.find(1, 2, 6) # returns an array for objects with IDs in (1, 2, 6)
# Person.find([7, 17]) # returns an array for objects with IDs in (7, 17)
# Person.find([1]) # returns an array for the object with ID = 1
# Person.find(1, :conditions => "administrator = 1", :order => "created_on DESC")
#
# Note that returned records may not be in the same order as the ids you
# provide since database rows are unordered. Give an explicit <tt>:order</tt>
# to ensure the results are sorted.
#
# ==== Examples
#
# # find first
# Person.find(:first) # returns the first object fetched by SELECT * FROM people
# Person.find(:first, :conditions => [ "user_name = ?", user_name])
# Person.find(:first, :conditions => [ "user_name = :u", { :u => user_name }])
# Person.find(:first, :order => "created_on DESC", :offset => 5)
#
# # find last
# Person.find(:last) # returns the last object fetched by SELECT * FROM people
# Person.find(:last, :conditions => [ "user_name = ?", user_name])
# Person.find(:last, :order => "created_on DESC", :offset => 5)
#
# # find all
# Person.find(:all) # returns an array of objects for all the rows fetched by SELECT * FROM people
# Person.find(:all, :conditions => [ "category IN (?)", categories], :limit => 50)
# Person.find(:all, :conditions => { :friends => ["Bob", "Steve", "Fred"] }
# Person.find(:all, :offset => 10, :limit => 10)
# Person.find(:all, :include => [ :account, :friends ])
# Person.find(:all, :group => "category")
#
# Example for find with a lock: Imagine two concurrent transactions:
# each will read <tt>person.visits == 2</tt>, add 1 to it, and save, resulting
# in two saves of <tt>person.visits = 3</tt>. By locking the row, the second
# transaction has to wait until the first is finished; we get the
# expected <tt>person.visits == 4</tt>.
#
# Person.transaction do
# person = Person.find(1, :lock => true)
# person.visits += 1
# person.save!
# end
def find(*args)
return to_a.find { |*block_args| yield(*block_args) } if block_given?
options = args.extract_options!
if options.present?
apply_finder_options(options).find(*args)
else
case args.first
when :first, :last, :all
send(args.first)
else
find_with_ids(*args)
end
end
end
# A convenience wrapper for <tt>find(:first, *args)</tt>. You can pass in all the
# same arguments to this method as you can to <tt>find(:first)</tt>.
def first(*args)
if args.any?
if args.first.kind_of?(Integer) || (loaded? && !args.first.kind_of?(Hash))
to_a.first(*args)
else
apply_finder_options(args.first).first
end
else
find_first
end
end
# A convenience wrapper for <tt>find(:last, *args)</tt>. You can pass in all the
# same arguments to this method as you can to <tt>find(:last)</tt>.
def last(*args)
if args.any?
if args.first.kind_of?(Integer) || (loaded? && !args.first.kind_of?(Hash))
to_a.last(*args)
else
apply_finder_options(args.first).last
end
else
find_last
end
end
# A convenience wrapper for <tt>find(:all, *args)</tt>. You can pass in all the
# same arguments to this method as you can to <tt>find(:all)</tt>.
def all(*args)
args.any? ? apply_finder_options(args.first).to_a : to_a
end
# Returns true if a record exists in the table that matches the +id+ or
# conditions given, or false otherwise. The argument can take five forms:
#
# * Integer - Finds the record with this primary key.
# * String - Finds the record with a primary key corresponding to this
# string (such as <tt>'5'</tt>).
# * Array - Finds the record that matches these +find+-style conditions
# (such as <tt>['color = ?', 'red']</tt>).
# * Hash - Finds the record that matches these +find+-style conditions
# (such as <tt>{:color => 'red'}</tt>).
# * No args - Returns false if the table is empty, true otherwise.
#
# For more information about specifying conditions as a Hash or Array,
# see the Conditions section in the introduction to ActiveRecord::Base.
#
# Note: You can't pass in a condition as a string (like <tt>name =
# 'Jamie'</tt>), since it would be sanitized and then queried against
# the primary key column, like <tt>id = 'name = \'Jamie\''</tt>.
#
# ==== Examples
# Person.exists?(5)
# Person.exists?('5')
# Person.exists?(:name => "David")
# Person.exists?(['name LIKE ?', "%#{query}%"])
# Person.exists?
def exists?(id = nil)
case id
when Array, Hash
where(id).exists?
else
relation = select(primary_key).limit(1)
relation = relation.where(primary_key.eq(id)) if id
relation.first ? true : false
end
end
protected
def find_with_associations
including = (@eager_load_values + @includes_values).uniq
join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(@klass, including, nil)
rows = construct_relation_for_association_find(join_dependency).to_a
join_dependency.instantiate(rows)
rescue ThrowResult
[]
end
def construct_relation_for_association_calculations
including = (@eager_load_values + @includes_values).uniq
join_dependency = ActiveRecord::Associations::ClassMethods::JoinDependency.new(@klass, including, arel.joins(arel))
relation = except(:includes, :eager_load, :preload)
apply_join_dependency(relation, join_dependency)
end
def construct_relation_for_association_find(join_dependency)
relation = except(:includes, :eager_load, :preload, :select).select(column_aliases(join_dependency))
apply_join_dependency(relation, join_dependency)
end
def apply_join_dependency(relation, join_dependency)
for association in join_dependency.join_associations
relation = association.join_relation(relation)
end
limitable_reflections = using_limitable_reflections?(join_dependency.reflections)
if !limitable_reflections && relation.limit_value
limited_id_condition = construct_limited_ids_condition(relation.except(:select))
relation = relation.where(limited_id_condition)
end
relation = relation.except(:limit, :offset) unless limitable_reflections
relation
end
def construct_limited_ids_condition(relation)
orders = relation.order_values.join(", ")
values = @klass.connection.distinct("#{@klass.connection.quote_table_name @klass.table_name}.#{@klass.primary_key}", orders)
ids_array = relation.select(values).collect {|row| row[@klass.primary_key]}
ids_array.empty? ? raise(ThrowResult) : primary_key.in(ids_array)
end
def find_by_attributes(match, attributes, *args)
conditions = attributes.inject({}) {|h, a| h[a] = args[attributes.index(a)]; h}
result = where(conditions).send(match.finder)
if match.bang? && result.blank?
raise RecordNotFound, "Couldn't find #{@klass.name} with #{conditions.to_a.collect {|p| p.join(' = ')}.join(', ')}"
else
result
end
end
def find_or_instantiator_by_attributes(match, attributes, *args)
protected_attributes_for_create, unprotected_attributes_for_create = {}, {}
args.each_with_index do |arg, i|
if arg.is_a?(Hash)
protected_attributes_for_create = args[i].with_indifferent_access
else
unprotected_attributes_for_create[attributes[i]] = args[i]
end
end
conditions = (protected_attributes_for_create.merge(unprotected_attributes_for_create)).slice(*attributes).symbolize_keys
record = where(conditions).first
unless record
record = @klass.new do |r|
r.send(:attributes=, protected_attributes_for_create, true) unless protected_attributes_for_create.empty?
r.send(:attributes=, unprotected_attributes_for_create, false) unless unprotected_attributes_for_create.empty?
end
yield(record) if block_given?
record.save if match.instantiator == :create
end
record
end
def find_with_ids(*ids)
return to_a.find { |*block_args| yield(*block_args) } if block_given?
expects_array = ids.first.kind_of?(Array)
return ids.first if expects_array && ids.first.empty?
ids = ids.flatten.compact.uniq
case ids.size
when 0
raise RecordNotFound, "Couldn't find #{@klass.name} without an ID"
when 1
result = find_one(ids.first)
expects_array ? [ result ] : result
else
find_some(ids)
end
end
def find_one(id)
record = where(primary_key.eq(id)).first
unless record
conditions = arel.send(:where_clauses).join(', ')
conditions = " [WHERE #{conditions}]" if conditions.present?
raise RecordNotFound, "Couldn't find #{@klass.name} with ID=#{id}#{conditions}"
end
record
end
def find_some(ids)
result = where(primary_key.in(ids)).all
expected_size =
if @limit_value && ids.size > @limit_value
@limit_value
else
ids.size
end
# 11 ids with limit 3, offset 9 should give 2 results.
if @offset_value && (ids.size - @offset_value < expected_size)
expected_size = ids.size - @offset_value
end
if result.size == expected_size
result
else
conditions = arel.send(:where_clauses).join(', ')
conditions = " [WHERE #{conditions}]" if conditions.present?
error = "Couldn't find all #{@klass.name.pluralize} with IDs "
error << "(#{ids.join(", ")})#{conditions} (found #{result.size} results, but was looking for #{expected_size})"
raise RecordNotFound, error
end
end
def find_first
if loaded?
@records.first
else
@first ||= limit(1).to_a[0]
end
end
def find_last
if loaded?
@records.last
else
@last ||= reverse_order.limit(1).to_a[0]
end
end
def column_aliases(join_dependency)
join_dependency.joins.collect{|join| join.column_names_with_alias.collect{|column_name, aliased_name|
"#{connection.quote_table_name join.aliased_table_name}.#{connection.quote_column_name column_name} AS #{aliased_name}"}}.flatten.join(", ")
end
def using_limitable_reflections?(reflections)
reflections.none?(&:collection?)
end
end
end
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