Module: ActiveRecord::QueryMethods
- Includes:
- ActiveModel::ForbiddenAttributesProtection
- Included in:
- Relation
- Defined in:
- lib/active_record/relation/query_methods.rb
Defined Under Namespace
Classes: WhereChain
Constant Summary collapse
- FROZEN_EMPTY_ARRAY =
[].freeze
- FROZEN_EMPTY_HASH =
{}.freeze
- VALID_UNSCOPING_VALUES =
Set.new([:where, :select, :group, :order, :lock, :limit, :offset, :joins, :left_outer_joins, :annotate, :includes, :from, :readonly, :having, :optimizer_hints])
Instance Method Summary collapse
-
#_select!(*fields) ⇒ Object
:nodoc:.
-
#and(other) ⇒ Object
Returns a new relation, which is the logical intersection of this relation and the one passed as an argument.
-
#and!(other) ⇒ Object
:nodoc:.
-
#annotate(*args) ⇒ Object
Adds an SQL comment to queries generated from this relation.
-
#annotate!(*args) ⇒ Object
Like #annotate, but modifies relation in place.
-
#arel(aliases = nil) ⇒ Object
Returns the Arel object associated with the relation.
-
#construct_join_dependency(associations, join_type) ⇒ Object
:nodoc:.
-
#create_with(value) ⇒ Object
Sets attributes to be used when creating new records from a relation object.
-
#create_with!(value) ⇒ Object
:nodoc:.
-
#distinct(value = true) ⇒ Object
Specifies whether the records should be unique or not.
-
#distinct!(value = true) ⇒ Object
Like #distinct, but modifies relation in place.
-
#eager_load(*args) ⇒ Object
Forces eager loading by performing a LEFT OUTER JOIN on
args
:. -
#eager_load!(*args) ⇒ Object
:nodoc:.
-
#excluding(*records) ⇒ Object
(also: #without)
Excludes the specified record (or collection of records) from the resulting relation.
-
#excluding!(records) ⇒ Object
:nodoc:.
-
#extending(*modules, &block) ⇒ Object
Used to extend a scope with additional methods, either through a module or through a block provided.
-
#extending!(*modules, &block) ⇒ Object
:nodoc:.
-
#extract_associated(association) ⇒ Object
Extracts a named
association
from the relation. -
#from(value, subquery_name = nil) ⇒ Object
Specifies the table from which the records will be fetched.
-
#from!(value, subquery_name = nil) ⇒ Object
:nodoc:.
-
#group(*args) ⇒ Object
Allows to specify a group attribute:.
-
#group!(*args) ⇒ Object
:nodoc:.
-
#having(opts, *rest) ⇒ Object
Allows to specify a HAVING clause.
-
#having!(opts, *rest) ⇒ Object
:nodoc:.
-
#in_order_of(column, values) ⇒ Object
Allows to specify an order by a specific set of values.
-
#includes(*args) ⇒ Object
Specify relationships to be included in the result set.
-
#includes!(*args) ⇒ Object
:nodoc:.
-
#invert_where ⇒ Object
Allows you to invert an entire where clause instead of manually applying conditions.
-
#invert_where! ⇒ Object
:nodoc:.
-
#joins(*args) ⇒ Object
Performs JOINs on
args
. -
#joins!(*args) ⇒ Object
:nodoc:.
-
#left_outer_joins(*args) ⇒ Object
(also: #left_joins)
Performs LEFT OUTER JOINs on
args
:. -
#left_outer_joins!(*args) ⇒ Object
:nodoc:.
-
#limit(value) ⇒ Object
Specifies a limit for the number of records to retrieve.
-
#limit!(value) ⇒ Object
:nodoc:.
-
#lock(locks = true) ⇒ Object
Specifies locking settings (default to
true
). -
#lock!(locks = true) ⇒ Object
:nodoc:.
-
#none ⇒ Object
Returns a chainable relation with zero records.
-
#none! ⇒ Object
:nodoc:.
-
#offset(value) ⇒ Object
Specifies the number of rows to skip before returning rows.
-
#offset!(value) ⇒ Object
:nodoc:.
-
#optimizer_hints(*args) ⇒ Object
Specify optimizer hints to be used in the SELECT statement.
-
#optimizer_hints!(*args) ⇒ Object
:nodoc:.
-
#or(other) ⇒ Object
Returns a new relation, which is the logical union of this relation and the one passed as an argument.
-
#or!(other) ⇒ Object
:nodoc:.
-
#order(*args) ⇒ Object
Applies an
ORDER BY
clause to a query. -
#order!(*args) ⇒ Object
Same as #order but operates on relation in-place instead of copying.
-
#preload(*args) ⇒ Object
Allows preloading of
args
, in the same way that #includes does:. -
#preload!(*args) ⇒ Object
:nodoc:.
-
#readonly(value = true) ⇒ Object
Sets readonly attributes for the returned relation.
-
#readonly!(value = true) ⇒ Object
:nodoc:.
-
#references(*table_names) ⇒ Object
Use to indicate that the given
table_names
are referenced by an SQL string, and should therefore be JOINed in any query rather than loaded separately. -
#references!(*table_names) ⇒ Object
:nodoc:.
-
#reorder(*args) ⇒ Object
Replaces any existing order defined on the relation with the specified order.
-
#reorder!(*args) ⇒ Object
Same as #reorder but operates on relation in-place instead of copying.
-
#reselect(*args) ⇒ Object
Allows you to change a previously set select statement.
-
#reselect!(*args) ⇒ Object
Same as #reselect but operates on relation in-place instead of copying.
-
#reverse_order ⇒ Object
Reverse the existing order clause on the relation.
-
#reverse_order! ⇒ Object
:nodoc:.
-
#rewhere(conditions) ⇒ Object
Allows you to change a previously set where condition for a given attribute, instead of appending to that condition.
-
#select(*fields) ⇒ Object
Works in two unique ways.
-
#skip_preloading! ⇒ Object
:nodoc:.
-
#skip_query_cache!(value = true) ⇒ Object
:nodoc:.
-
#strict_loading(value = true) ⇒ Object
Sets the returned relation to strict_loading mode.
-
#strict_loading!(value = true) ⇒ Object
:nodoc:.
-
#structurally_compatible?(other) ⇒ Boolean
Checks whether the given relation is structurally compatible with this relation, to determine if it’s possible to use the #and and #or methods without raising an error.
-
#uniq!(name) ⇒ Object
Deduplicate multiple values.
-
#unscope(*args) ⇒ Object
Removes an unwanted relation that is already defined on a chain of relations.
-
#unscope!(*args) ⇒ Object
:nodoc:.
-
#where(*args) ⇒ Object
Returns a new relation, which is the result of filtering the current relation according to the conditions in the arguments.
-
#where!(opts, *rest) ⇒ Object
:nodoc:.
Instance Method Details
#_select!(*fields) ⇒ Object
:nodoc:
325 326 327 328 |
# File 'lib/active_record/relation/query_methods.rb', line 325 def _select!(*fields) # :nodoc: self.select_values |= fields self end |
#and(other) ⇒ Object
Returns a new relation, which is the logical intersection of this relation and the one passed as an argument.
The two relations must be structurally compatible: they must be scoping the same model, and they must differ only by #where (if no #group has been defined) or #having (if a #group is present).
Post.where(id: [1, 2]).and(Post.where(id: [2, 3]))
# SELECT `posts`.* FROM `posts` WHERE `posts`.`id` IN (1, 2) AND `posts`.`id` IN (2, 3)
863 864 865 866 867 868 869 |
# File 'lib/active_record/relation/query_methods.rb', line 863 def and(other) if other.is_a?(Relation) spawn.and!(other) else raise ArgumentError, "You have passed #{other.class.name} object to #and. Pass an ActiveRecord::Relation object instead." end end |
#and!(other) ⇒ Object
:nodoc:
871 872 873 874 875 876 877 878 879 880 881 882 883 |
# File 'lib/active_record/relation/query_methods.rb', line 871 def and!(other) # :nodoc: incompatible_values = structurally_incompatible_values_for(other) unless incompatible_values.empty? raise ArgumentError, "Relation passed to #and must be structurally compatible. Incompatible values: #{incompatible_values}" end self.where_clause |= other.where_clause self.having_clause |= other.having_clause self.references_values |= other.references_values self end |
#annotate(*args) ⇒ Object
Adds an SQL comment to queries generated from this relation. For example:
User.annotate("selecting user names").select(:name)
# SELECT "users"."name" FROM "users" /* selecting user names */
User.annotate("selecting", "user", "names").select(:name)
# SELECT "users"."name" FROM "users" /* selecting */ /* user */ /* names */
The SQL block comment delimiters, “/*” and “*/”, will be added automatically.
Some escaping is performed, however untrusted user input should not be used.
1239 1240 1241 1242 |
# File 'lib/active_record/relation/query_methods.rb', line 1239 def annotate(*args) check_if_method_has_arguments!(__callee__, args) spawn.annotate!(*args) end |
#annotate!(*args) ⇒ Object
Like #annotate, but modifies relation in place.
1245 1246 1247 1248 |
# File 'lib/active_record/relation/query_methods.rb', line 1245 def annotate!(*args) # :nodoc: self.annotate_values += args self end |
#arel(aliases = nil) ⇒ Object
Returns the Arel object associated with the relation.
1300 1301 1302 |
# File 'lib/active_record/relation/query_methods.rb', line 1300 def arel(aliases = nil) # :nodoc: @arel ||= build_arel(aliases) end |
#construct_join_dependency(associations, join_type) ⇒ Object
:nodoc:
1304 1305 1306 1307 1308 |
# File 'lib/active_record/relation/query_methods.rb', line 1304 def construct_join_dependency(associations, join_type) # :nodoc: ActiveRecord::Associations::JoinDependency.new( klass, table, associations, join_type ) end |
#create_with(value) ⇒ Object
Sets attributes to be used when creating new records from a relation object.
users = User.where(name: 'Oscar')
users.new.name # => 'Oscar'
users = users.create_with(name: 'DHH')
users.new.name # => 'DHH'
You can pass nil
to #create_with to reset attributes:
users = users.create_with(nil)
users.new.name # => 'Oscar'
1056 1057 1058 |
# File 'lib/active_record/relation/query_methods.rb', line 1056 def create_with(value) spawn.create_with!(value) end |
#create_with!(value) ⇒ Object
:nodoc:
1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 |
# File 'lib/active_record/relation/query_methods.rb', line 1060 def create_with!(value) # :nodoc: if value value = sanitize_forbidden_attributes(value) self.create_with_value = create_with_value.merge(value) else self.create_with_value = FROZEN_EMPTY_HASH end self end |
#distinct(value = true) ⇒ Object
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).distinct
# Returns 1 record per distinct name
User.select(:name).distinct.distinct(false)
# You can also remove the uniqueness
1120 1121 1122 |
# File 'lib/active_record/relation/query_methods.rb', line 1120 def distinct(value = true) spawn.distinct!(value) end |
#distinct!(value = true) ⇒ Object
Like #distinct, but modifies relation in place.
1125 1126 1127 1128 |
# File 'lib/active_record/relation/query_methods.rb', line 1125 def distinct!(value = true) # :nodoc: self.distinct_value = value self end |
#eager_load(*args) ⇒ Object
Forces eager loading by performing a LEFT OUTER JOIN on args
:
User.eager_load(:posts)
# SELECT "users"."id" AS t0_r0, "users"."name" AS t0_r1, ...
# FROM "users" LEFT OUTER JOIN "posts" ON "posts"."user_id" =
# "users"."id"
215 216 217 218 |
# File 'lib/active_record/relation/query_methods.rb', line 215 def eager_load(*args) check_if_method_has_arguments!(__callee__, args) spawn.eager_load!(*args) end |
#eager_load!(*args) ⇒ Object
:nodoc:
220 221 222 223 |
# File 'lib/active_record/relation/query_methods.rb', line 220 def eager_load!(*args) # :nodoc: self.eager_load_values |= args self end |
#excluding(*records) ⇒ Object Also known as: without
Excludes the specified record (or collection of records) from the resulting relation. For example:
Post.excluding(post)
# SELECT "posts".* FROM "posts" WHERE "posts"."id" != 1
Post.excluding(post_one, post_two)
# SELECT "posts".* FROM "posts" WHERE "posts"."id" NOT IN (1, 2)
This can also be called on associations. As with the above example, either a single record of collection thereof may be specified:
post = Post.find(1)
comment = Comment.find(2)
post.comments.excluding(comment)
# SELECT "comments".* FROM "comments" WHERE "comments"."post_id" = 1 AND "comments"."id" != 2
This is short-hand for .where.not(id: post.id)
and .where.not(id: [post_one.id, post_two.id])
.
An ArgumentError
will be raised if either no records are specified, or if any of the records in the collection (if a collection is passed in) are not instances of the same model that the relation is scoping.
1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 |
# File 'lib/active_record/relation/query_methods.rb', line 1281 def excluding(*records) records.flatten!(1) records.compact! unless records.all?(klass) raise ArgumentError, "You must only pass a single or collection of #{klass.name} objects to ##{__callee__}." end spawn.excluding!(records) end |
#excluding!(records) ⇒ Object
:nodoc:
1293 1294 1295 1296 1297 |
# File 'lib/active_record/relation/query_methods.rb', line 1293 def excluding!(records) # :nodoc: predicates = [ predicate_builder[primary_key, records].invert ] self.where_clause += Relation::WhereClause.new(predicates) self end |
#extending(*modules, &block) ⇒ Object
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.all.extending(Pagination)
scope.page(params[:page])
You can also pass a list of modules:
scope = Model.all.extending(Pagination, SomethingElse)
Using a block
scope = Model.all.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.all.extending(Pagination) do
def per_page(number)
# pagination code goes here
end
end
1166 1167 1168 1169 1170 1171 1172 |
# File 'lib/active_record/relation/query_methods.rb', line 1166 def extending(*modules, &block) if modules.any? || block spawn.extending!(*modules, &block) else self end end |
#extending!(*modules, &block) ⇒ Object
:nodoc:
1174 1175 1176 1177 1178 1179 1180 1181 1182 |
# File 'lib/active_record/relation/query_methods.rb', line 1174 def extending!(*modules, &block) # :nodoc: modules << Module.new(&block) if block modules.flatten! self.extending_values += modules extend(*extending_values) if extending_values.any? self end |
#extract_associated(association) ⇒ Object
Extracts a named association
from the relation. The named association is first preloaded, then the individual association records are collected from the relation. Like so:
account.memberships.extract_associated(:user)
# => Returns collection of User records
This is short-hand for:
account.memberships.preload(:user).collect(&:user)
248 249 250 |
# File 'lib/active_record/relation/query_methods.rb', line 248 def extract_associated(association) preload(association).collect(&association) end |
#from(value, subquery_name = nil) ⇒ Object
Specifies the table from which the records will be fetched. For example:
Topic.select('title').from('posts')
# SELECT title FROM posts
Can accept other relation objects. For example:
Topic.select('title').from(Topic.approved)
# SELECT title FROM (SELECT * FROM topics WHERE approved = 't') subquery
Passing a second argument (string or symbol), creates the alias for the SQL from clause. Otherwise the alias “subquery” is used:
Topic.select('a.title').from(Topic.approved, :a)
# SELECT a.title FROM (SELECT * FROM topics WHERE approved = 't') a
It does not add multiple arguments to the SQL from clause. The last from
chained is the one used:
Topic.select('title').from(Topic.approved).from(Topic.inactive)
# SELECT title FROM (SELECT topics.* FROM topics WHERE topics.active = 'f') subquery
For multiple arguments for the SQL from clause, you can pass a string with the exact elements in the SQL from list:
color = "red"
Color
.from("colors c, JSONB_ARRAY_ELEMENTS(colored_things) AS colorvalues(colorvalue)")
.where("colorvalue->>'color' = ?", color)
.select("c.*").to_a
# SELECT c.*
# FROM colors c, JSONB_ARRAY_ELEMENTS(colored_things) AS colorvalues(colorvalue)
# WHERE (colorvalue->>'color' = 'red')
1101 1102 1103 |
# File 'lib/active_record/relation/query_methods.rb', line 1101 def from(value, subquery_name = nil) spawn.from!(value, subquery_name) end |
#from!(value, subquery_name = nil) ⇒ Object
:nodoc:
1105 1106 1107 1108 |
# File 'lib/active_record/relation/query_methods.rb', line 1105 def from!(value, subquery_name = nil) # :nodoc: self.from_clause = Relation::FromClause.new(value, subquery_name) self end |
#group(*args) ⇒ Object
Allows to specify a group attribute:
User.group(:name)
# SELECT "users".* FROM "users" GROUP BY name
Returns an array with distinct records based on the group
attribute:
User.select([:id, :name])
# => [#<User id: 1, name: "Oscar">, #<User id: 2, name: "Oscar">, #<User id: 3, name: "Foo">]
User.group(:name)
# => [#<User id: 3, name: "Foo", ...>, #<User id: 2, name: "Oscar", ...>]
User.group('name AS grouped_name, age')
# => [#<User id: 3, name: "Foo", age: 21, ...>, #<User id: 2, name: "Oscar", age: 21, ...>, #<User id: 5, name: "Foo", age: 23, ...>]
Passing in an array of attributes to group by is also supported.
User.select([:id, :first_name]).group(:id, :first_name).first(3)
# => [#<User id: 1, first_name: "Bill">, #<User id: 2, first_name: "Earl">, #<User id: 3, first_name: "Beto">]
371 372 373 374 |
# File 'lib/active_record/relation/query_methods.rb', line 371 def group(*args) check_if_method_has_arguments!(__callee__, args) spawn.group!(*args) end |
#group!(*args) ⇒ Object
:nodoc:
376 377 378 379 |
# File 'lib/active_record/relation/query_methods.rb', line 376 def group!(*args) # :nodoc: self.group_values += args self end |
#having(opts, *rest) ⇒ Object
Allows to specify a HAVING clause. Note that you can’t use HAVING without also specifying a GROUP clause.
Order.having('SUM(price) > 30').group('user_id')
921 922 923 |
# File 'lib/active_record/relation/query_methods.rb', line 921 def having(opts, *rest) opts.blank? ? self : spawn.having!(opts, *rest) end |
#having!(opts, *rest) ⇒ Object
:nodoc:
925 926 927 928 |
# File 'lib/active_record/relation/query_methods.rb', line 925 def having!(opts, *rest) # :nodoc: self.having_clause += build_having_clause(opts, rest) self end |
#in_order_of(column, values) ⇒ Object
Allows to specify an order by a specific set of values.
User.in_order_of(:id, [1, 5, 3])
# SELECT "users".* FROM "users"
# WHERE "users"."id" IN (1, 5, 3)
# ORDER BY CASE
# WHEN "users"."id" = 1 THEN 1
# WHEN "users"."id" = 5 THEN 2
# WHEN "users"."id" = 3 THEN 3
# END ASC
458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 |
# File 'lib/active_record/relation/query_methods.rb', line 458 def in_order_of(column, values) klass.disallow_raw_sql!([column], permit: connection.column_name_with_order_matcher) return spawn.none! if values.empty? references = column_references([column]) self.references_values |= references unless references.empty? values = values.map { |value| type_caster.type_cast_for_database(column, value) } arel_column = column.is_a?(Symbol) ? order_column(column.to_s) : column where_clause = if values.include?(nil) arel_column.in(values.compact).or(arel_column.eq(nil)) else arel_column.in(values) end spawn .order!(build_case_for_value_position(arel_column, values)) .where!(where_clause) end |
#includes(*args) ⇒ Object
Specify relationships to be included in the result set. For example:
users = User.includes(:address)
users.each do |user|
user.address.city
end
allows you to access the address
attribute of the User
model without firing an additional query. This will often result in a performance improvement over a simple join.
You can also specify multiple relationships, like this:
users = User.includes(:address, :friends)
Loading nested relationships is possible using a Hash:
users = User.includes(:address, friends: [:address, :followers])
Conditions
If you want to add string conditions to your included models, you’ll have to explicitly reference them. For example:
User.includes(:posts).where('posts.name = ?', 'example')
Will throw an error, but this will work:
User.includes(:posts).where('posts.name = ?', 'example').references(:posts)
Note that #includes works with association names while #references needs the actual table name.
If you pass the conditions via hash, you don’t need to call #references explicitly, as #where references the tables for you. For example, this will work correctly:
User.includes(:posts).where(posts: { name: 'example' })
199 200 201 202 |
# File 'lib/active_record/relation/query_methods.rb', line 199 def includes(*args) check_if_method_has_arguments!(__callee__, args) spawn.includes!(*args) end |
#includes!(*args) ⇒ Object
:nodoc:
204 205 206 207 |
# File 'lib/active_record/relation/query_methods.rb', line 204 def includes!(*args) # :nodoc: self.includes_values |= args self end |
#invert_where ⇒ Object
Allows you to invert an entire where clause instead of manually applying conditions.
class User
scope :active, -> { where(accepted: true, locked: false) }
end
User.where(accepted: true)
# WHERE `accepted` = 1
User.where(accepted: true).invert_where
# WHERE `accepted` != 1
User.active
# WHERE `accepted` = 1 AND `locked` = 0
User.active.invert_where
# WHERE NOT (`accepted` = 1 AND `locked` = 0)
Be careful because this inverts all conditions before invert_where
call.
class User
scope :active, -> { where(accepted: true, locked: false) }
scope :inactive, -> { active.invert_where } # Do not attempt it
end
# It also inverts `where(role: 'admin')` unexpectedly.
User.where(role: 'admin').inactive
# WHERE NOT (`role` = 'admin' AND `accepted` = 1 AND `locked` = 0)
829 830 831 |
# File 'lib/active_record/relation/query_methods.rb', line 829 def invert_where spawn.invert_where! end |
#invert_where! ⇒ Object
:nodoc:
833 834 835 836 |
# File 'lib/active_record/relation/query_methods.rb', line 833 def invert_where! # :nodoc: self.where_clause = where_clause.invert self end |
#joins(*args) ⇒ Object
Performs JOINs on args
. The given symbol(s) should match the name of the association(s).
User.joins(:posts)
# SELECT "users".*
# FROM "users"
# INNER JOIN "posts" ON "posts"."user_id" = "users"."id"
Multiple joins:
User.joins(:posts, :account)
# SELECT "users".*
# FROM "users"
# INNER JOIN "posts" ON "posts"."user_id" = "users"."id"
# INNER JOIN "accounts" ON "accounts"."id" = "users"."account_id"
Nested joins:
User.joins(posts: [:comments])
# SELECT "users".*
# FROM "users"
# INNER JOIN "posts" ON "posts"."user_id" = "users"."id"
# INNER JOIN "comments" ON "comments"."post_id" = "posts"."id"
You can use strings in order to customize your joins:
User.joins("LEFT JOIN bookmarks ON bookmarks.bookmarkable_type = 'Post' AND bookmarks.user_id = users.id")
# SELECT "users".* FROM "users" LEFT JOIN bookmarks ON bookmarks.bookmarkable_type = 'Post' AND bookmarks.user_id = users.id
604 605 606 607 |
# File 'lib/active_record/relation/query_methods.rb', line 604 def joins(*args) check_if_method_has_arguments!(__callee__, args) spawn.joins!(*args) end |
#joins!(*args) ⇒ Object
:nodoc:
609 610 611 612 |
# File 'lib/active_record/relation/query_methods.rb', line 609 def joins!(*args) # :nodoc: self.joins_values |= args self end |
#left_outer_joins(*args) ⇒ Object Also known as: left_joins
Performs LEFT OUTER JOINs on args
:
User.left_outer_joins(:posts)
=> SELECT "users".* FROM "users" LEFT OUTER JOIN "posts" ON "posts"."user_id" = "users"."id"
619 620 621 622 |
# File 'lib/active_record/relation/query_methods.rb', line 619 def left_outer_joins(*args) check_if_method_has_arguments!(__callee__, args) spawn.left_outer_joins!(*args) end |
#left_outer_joins!(*args) ⇒ Object
:nodoc:
625 626 627 628 |
# File 'lib/active_record/relation/query_methods.rb', line 625 def left_outer_joins!(*args) # :nodoc: self.left_outer_joins_values |= args self end |
#limit(value) ⇒ Object
Specifies a limit for the number of records to retrieve.
User.limit(10) # generated SQL has 'LIMIT 10'
User.limit(10).limit(20) # generated SQL has 'LIMIT 20'
935 936 937 |
# File 'lib/active_record/relation/query_methods.rb', line 935 def limit(value) spawn.limit!(value) end |
#limit!(value) ⇒ Object
:nodoc:
939 940 941 942 |
# File 'lib/active_record/relation/query_methods.rb', line 939 def limit!(value) # :nodoc: self.limit_value = value self end |
#lock(locks = true) ⇒ Object
Specifies locking settings (default to true
). For more information on locking, please see ActiveRecord::Locking.
962 963 964 |
# File 'lib/active_record/relation/query_methods.rb', line 962 def lock(locks = true) spawn.lock!(locks) end |
#lock!(locks = true) ⇒ Object
:nodoc:
966 967 968 969 970 971 972 973 974 975 |
# File 'lib/active_record/relation/query_methods.rb', line 966 def lock!(locks = true) # :nodoc: case locks when String, TrueClass, NilClass self.lock_value = locks || true else self.lock_value = false end self end |
#none ⇒ Object
Returns a chainable relation with zero records.
The returned relation implements the Null Object pattern. It is an object with defined null behavior and always returns an empty array of records without querying 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 # It can't be chained if [] is returned.
end
end
1005 1006 1007 |
# File 'lib/active_record/relation/query_methods.rb', line 1005 def none spawn.none! end |
#none! ⇒ Object
:nodoc:
1009 1010 1011 |
# File 'lib/active_record/relation/query_methods.rb', line 1009 def none! # :nodoc: where!("1=0").extending!(NullRelation) end |
#offset(value) ⇒ Object
Specifies the number of rows to skip before returning rows.
User.offset(10) # generated SQL has "OFFSET 10"
Should be used with order.
User.offset(10).order("name ASC")
951 952 953 |
# File 'lib/active_record/relation/query_methods.rb', line 951 def offset(value) spawn.offset!(value) end |
#offset!(value) ⇒ Object
:nodoc:
955 956 957 958 |
# File 'lib/active_record/relation/query_methods.rb', line 955 def offset!(value) # :nodoc: self.offset_value = value self end |
#optimizer_hints(*args) ⇒ Object
Specify optimizer hints to be used in the SELECT statement.
Example (for MySQL):
Topic.optimizer_hints("MAX_EXECUTION_TIME(50000)", "NO_INDEX_MERGE(topics)")
# SELECT /*+ MAX_EXECUTION_TIME(50000) NO_INDEX_MERGE(topics) */ `topics`.* FROM `topics`
Example (for PostgreSQL with pg_hint_plan):
Topic.optimizer_hints("SeqScan(topics)", "Parallel(topics 8)")
# SELECT /*+ SeqScan(topics) Parallel(topics 8) */ "topics".* FROM "topics"
1195 1196 1197 1198 |
# File 'lib/active_record/relation/query_methods.rb', line 1195 def optimizer_hints(*args) check_if_method_has_arguments!(__callee__, args) spawn.optimizer_hints!(*args) end |
#optimizer_hints!(*args) ⇒ Object
:nodoc:
1200 1201 1202 1203 |
# File 'lib/active_record/relation/query_methods.rb', line 1200 def optimizer_hints!(*args) # :nodoc: self.optimizer_hints_values |= args self end |
#or(other) ⇒ Object
Returns a new relation, which is the logical union of this relation and the one passed as an argument.
The two relations must be structurally compatible: they must be scoping the same model, and they must differ only by #where (if no #group has been defined) or #having (if a #group is present).
Post.where("id = 1").or(Post.where("author_id = 3"))
# SELECT `posts`.* FROM `posts` WHERE ((id = 1) OR (author_id = 3))
895 896 897 898 899 900 901 |
# File 'lib/active_record/relation/query_methods.rb', line 895 def or(other) if other.is_a?(Relation) spawn.or!(other) else raise ArgumentError, "You have passed #{other.class.name} object to #or. Pass an ActiveRecord::Relation object instead." end end |
#or!(other) ⇒ Object
:nodoc:
903 904 905 906 907 908 909 910 911 912 913 914 915 |
# File 'lib/active_record/relation/query_methods.rb', line 903 def or!(other) # :nodoc: incompatible_values = structurally_incompatible_values_for(other) unless incompatible_values.empty? raise ArgumentError, "Relation passed to #or must be structurally compatible. Incompatible values: #{incompatible_values}" end self.where_clause = self.where_clause.or(other.where_clause) self.having_clause = having_clause.or(other.having_clause) self.references_values |= other.references_values self end |
#order(*args) ⇒ Object
Applies an ORDER BY
clause to a query.
#order accepts arguments in one of several formats.
symbols
The symbol represents the name of the column you want to order the results by.
User.order(:name)
# SELECT "users".* FROM "users" ORDER BY "users"."name" ASC
By default, the order is ascending. If you want descending order, you can map the column name symbol to :desc
.
User.order(email: :desc)
# SELECT "users".* FROM "users" ORDER BY "users"."email" DESC
Multiple columns can be passed this way, and they will be applied in the order specified.
User.order(:name, email: :desc)
# SELECT "users".* FROM "users" ORDER BY "users"."name" ASC, "users"."email" DESC
strings
Strings are passed directly to the database, allowing you to specify simple SQL expressions.
This could be a source of SQL injection, so only strings composed of plain column names and simple function(column_name)
expressions with optional ASC
/DESC
modifiers are allowed.
User.order('name')
# SELECT "users".* FROM "users" ORDER BY name
User.order('name DESC')
# SELECT "users".* FROM "users" ORDER BY name DESC
User.order('name DESC, email')
# SELECT "users".* FROM "users" ORDER BY name DESC, email
Arel
If you need to pass in complicated expressions that you have verified are safe for the database, you can use Arel.
User.order(Arel.sql('end_date - start_date'))
# SELECT "users".* FROM "users" ORDER BY end_date - start_date
Custom query syntax, like JSON columns for Postgres, is supported in this way.
User.order(Arel.sql("payload->>'kind'"))
# SELECT "users".* FROM "users" ORDER BY payload->>'kind'
433 434 435 436 437 438 |
# File 'lib/active_record/relation/query_methods.rb', line 433 def order(*args) check_if_method_has_arguments!(__callee__, args) do sanitize_order_arguments(args) end spawn.order!(*args) end |
#order!(*args) ⇒ Object
Same as #order but operates on relation in-place instead of copying.
441 442 443 444 445 |
# File 'lib/active_record/relation/query_methods.rb', line 441 def order!(*args) # :nodoc: preprocess_order_args(args) unless args.empty? self.order_values |= args self end |
#preload(*args) ⇒ Object
Allows preloading of args
, in the same way that #includes does:
User.preload(:posts)
# SELECT "posts".* FROM "posts" WHERE "posts"."user_id" IN (1, 2, 3)
229 230 231 232 |
# File 'lib/active_record/relation/query_methods.rb', line 229 def preload(*args) check_if_method_has_arguments!(__callee__, args) spawn.preload!(*args) end |
#preload!(*args) ⇒ Object
:nodoc:
234 235 236 237 |
# File 'lib/active_record/relation/query_methods.rb', line 234 def preload!(*args) # :nodoc: self.preload_values |= args self end |
#readonly(value = true) ⇒ Object
Sets readonly attributes for the returned relation. If value is true (default), attempting to update a record will result in an error.
users = User.readonly
users.first.save
=> ActiveRecord::ReadOnlyRecord: User is marked as readonly
1019 1020 1021 |
# File 'lib/active_record/relation/query_methods.rb', line 1019 def readonly(value = true) spawn.readonly!(value) end |
#readonly!(value = true) ⇒ Object
:nodoc:
1023 1024 1025 1026 |
# File 'lib/active_record/relation/query_methods.rb', line 1023 def readonly!(value = true) # :nodoc: self.readonly_value = value self end |
#references(*table_names) ⇒ Object
Use to indicate that the given table_names
are referenced by an SQL string, and should therefore be JOINed in any query rather than loaded separately. This method only works in conjunction with #includes. See #includes for more details.
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
262 263 264 265 |
# File 'lib/active_record/relation/query_methods.rb', line 262 def references(*table_names) check_if_method_has_arguments!(__callee__, table_names) spawn.references!(*table_names) end |
#references!(*table_names) ⇒ Object
:nodoc:
267 268 269 270 |
# File 'lib/active_record/relation/query_methods.rb', line 267 def references!(*table_names) # :nodoc: self.references_values |= table_names self end |
#reorder(*args) ⇒ Object
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’.
489 490 491 492 493 494 |
# File 'lib/active_record/relation/query_methods.rb', line 489 def reorder(*args) check_if_method_has_arguments!(__callee__, args) do sanitize_order_arguments(args) end spawn.reorder!(*args) end |
#reorder!(*args) ⇒ Object
Same as #reorder but operates on relation in-place instead of copying.
497 498 499 500 501 502 503 |
# File 'lib/active_record/relation/query_methods.rb', line 497 def reorder!(*args) # :nodoc: preprocess_order_args(args) args.uniq! self.reordering_value = true self.order_values = args self end |
#reselect(*args) ⇒ Object
Allows you to change a previously set select statement.
Post.select(:title, :body)
# SELECT `posts`.`title`, `posts`.`body` FROM `posts`
Post.select(:title, :body).reselect(:created_at)
# SELECT `posts`.`created_at` FROM `posts`
This is short-hand for unscope(:select).select(fields)
. Note that we’re unscoping the entire select statement.
340 341 342 343 |
# File 'lib/active_record/relation/query_methods.rb', line 340 def reselect(*args) check_if_method_has_arguments!(__callee__, args) spawn.reselect!(*args) end |
#reselect!(*args) ⇒ Object
Same as #reselect but operates on relation in-place instead of copying.
346 347 348 349 |
# File 'lib/active_record/relation/query_methods.rb', line 346 def reselect!(*args) # :nodoc: self.select_values = args self end |
#reverse_order ⇒ Object
Reverse the existing order clause on the relation.
User.order('name ASC').reverse_order # generated SQL has 'ORDER BY name DESC'
1208 1209 1210 |
# File 'lib/active_record/relation/query_methods.rb', line 1208 def reverse_order spawn.reverse_order! end |
#reverse_order! ⇒ Object
:nodoc:
1212 1213 1214 1215 1216 |
# File 'lib/active_record/relation/query_methods.rb', line 1212 def reverse_order! # :nodoc: orders = order_values.compact_blank self.order_values = reverse_sql_order(orders) self end |
#rewhere(conditions) ⇒ Object
Allows you to change a previously set where condition for a given attribute, instead of appending to that condition.
Post.where(trashed: true).where(trashed: false)
# WHERE `trashed` = 1 AND `trashed` = 0
Post.where(trashed: true).rewhere(trashed: false)
# WHERE `trashed` = 0
Post.where(active: true).where(trashed: true).rewhere(trashed: false)
# WHERE `active` = 1 AND `trashed` = 0
This is short-hand for unscope(where: conditions.keys).where(conditions)
. Note that unlike reorder, we’re only unscoping the named conditions – not the entire where statement.
791 792 793 794 795 796 797 798 |
# File 'lib/active_record/relation/query_methods.rb', line 791 def rewhere(conditions) scope = spawn where_clause = scope.build_where_clause(conditions) scope.unscope!(where: where_clause.extract_attributes) scope.where_clause += where_clause scope end |
#select(*fields) ⇒ Object
Works in two unique ways.
First: takes a block so it can be used just like Array#select
.
Model.all.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 id: nil, 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 id: nil, field: "value", other_field: "value", and_one_more: "value">]
You can also use one or more strings, which will be used unchanged as SELECT fields.
Model.select('field AS field_one', 'other_field AS field_two')
# => [#<Model id: nil, field_one: "value", field_two: "value">]
If an alias was specified, it will be accessible from the resulting objects:
Model.select('field AS field_one').first.field_one
# => "value"
Accessing attributes of an object that do not have fields retrieved by a select except id
will throw ActiveModel::MissingAttributeError:
Model.select(:field).first.other_field
# => ActiveModel::MissingAttributeError: missing attribute: other_field
312 313 314 315 316 317 318 319 320 321 322 323 |
# File 'lib/active_record/relation/query_methods.rb', line 312 def select(*fields) if block_given? if fields.any? raise ArgumentError, "`select' with block doesn't take arguments." end return super() end check_if_method_has_arguments!(__callee__, fields, "Call `select' with at least one field.") spawn._select!(*fields) end |
#skip_preloading! ⇒ Object
:nodoc:
1223 1224 1225 1226 |
# File 'lib/active_record/relation/query_methods.rb', line 1223 def skip_preloading! # :nodoc: self.skip_preloading_value = true self end |
#skip_query_cache!(value = true) ⇒ Object
:nodoc:
1218 1219 1220 1221 |
# File 'lib/active_record/relation/query_methods.rb', line 1218 def skip_query_cache!(value = true) # :nodoc: self.skip_query_cache_value = value self end |
#strict_loading(value = true) ⇒ Object
Sets the returned relation to strict_loading mode. This will raise an error if the record tries to lazily load an association.
user = User.strict_loading.first
user.comments.to_a
=> ActiveRecord::StrictLoadingViolationError
1034 1035 1036 |
# File 'lib/active_record/relation/query_methods.rb', line 1034 def strict_loading(value = true) spawn.strict_loading!(value) end |
#strict_loading!(value = true) ⇒ Object
:nodoc:
1038 1039 1040 1041 |
# File 'lib/active_record/relation/query_methods.rb', line 1038 def strict_loading!(value = true) # :nodoc: self.strict_loading_value = value self end |
#structurally_compatible?(other) ⇒ Boolean
Checks whether the given relation is structurally compatible with this relation, to determine if it’s possible to use the #and and #or methods without raising an error. Structurally compatible is defined as: they must be scoping the same model, and they must differ only by #where (if no #group has been defined) or #having (if a #group is present).
Post.where("id = 1").structurally_compatible?(Post.where("author_id = 3"))
# => true
Post.joins(:comments).structurally_compatible?(Post.where("id = 1"))
# => false
849 850 851 |
# File 'lib/active_record/relation/query_methods.rb', line 849 def structurally_compatible?(other) structurally_incompatible_values_for(other).empty? end |
#uniq!(name) ⇒ Object
Deduplicate multiple values.
1251 1252 1253 1254 1255 1256 |
# File 'lib/active_record/relation/query_methods.rb', line 1251 def uniq!(name) if values = @values[name] values.uniq! if values.is_a?(Array) && !values.empty? end self end |
#unscope(*args) ⇒ Object
Removes an unwanted relation that is already defined on a chain of relations. This is useful when passing around chains of relations and would like to modify the relations without reconstructing the entire chain.
User.order('email DESC').unscope(:order) == User.all
The method arguments are symbols which correspond to the names of the methods which should be unscoped. The valid arguments are given in VALID_UNSCOPING_VALUES. The method can also be called with multiple arguments. For example:
User.order('email DESC').select('id').where(name: "John")
.unscope(:order, :select, :where) == User.all
One can additionally pass a hash as an argument to unscope specific :where
values. This is done by passing a hash with a single key-value pair. The key should be :where
and the value should be the where value to unscope. For example:
User.where(name: "John", active: true).unscope(where: :name)
== User.where(active: true)
This method is similar to #except, but unlike #except, it persists across merges:
User.order('email').merge(User.except(:order))
== User.order('email')
User.order('email').merge(User.unscope(:order))
== User.all
This means it can be used in association definitions:
has_many :comments, -> { unscope(where: :trashed) }
542 543 544 545 |
# File 'lib/active_record/relation/query_methods.rb', line 542 def unscope(*args) check_if_method_has_arguments!(__callee__, args) spawn.unscope!(*args) end |
#unscope!(*args) ⇒ Object
:nodoc:
547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 |
# File 'lib/active_record/relation/query_methods.rb', line 547 def unscope!(*args) # :nodoc: self.unscope_values += args args.each do |scope| case scope when Symbol scope = :left_outer_joins if scope == :left_joins if !VALID_UNSCOPING_VALUES.include?(scope) raise ArgumentError, "Called unscope() with invalid unscoping argument ':#{scope}'. Valid arguments are :#{VALID_UNSCOPING_VALUES.to_a.join(", :")}." end assert_mutability! @values.delete(scope) when Hash scope.each do |key, target_value| if key != :where raise ArgumentError, "Hash arguments in .unscope(*args) must have :where as the key." end target_values = resolve_arel_attributes(Array.wrap(target_value)) self.where_clause = where_clause.except(*target_values) end else raise ArgumentError, "Unrecognized scoping: #{args.inspect}. Use .unscope(where: :attribute_name) or .unscope(:order), for example." end end self end |
#where(*args) ⇒ Object
Returns a new relation, which is the result of filtering the current relation according to the conditions in the arguments.
#where accepts conditions in one of several formats. In the examples below, the resulting SQL is given as an illustration; the actual query generated may be different depending on the database adapter.
string
A single string, without additional arguments, is passed to the query constructor as an SQL fragment, and used in the where clause of the query.
Client.where("orders_count = '2'")
# SELECT * from clients where orders_count = '2';
Note that building your own string from user input may expose your application to injection attacks if not done properly. As an alternative, it is recommended to use one of the following methods.
array
If an array is passed, then the first element of the array is treated as a template, and the remaining elements are inserted into the template to generate the condition. Active Record takes care of building the query to avoid injection attacks, and will convert from the ruby type to the database type where needed. Elements are inserted into the string in the order in which they appear.
User.where(["name = ? and email = ?", "Joe", "[email protected]"])
# SELECT * FROM users WHERE name = 'Joe' AND email = '[email protected]';
Alternatively, you can use named placeholders in the template, and pass a hash as the second element of the array. The names in the template are replaced with the corresponding values from the hash.
User.where(["name = :name and email = :email", { name: "Joe", email: "[email protected]" }])
# SELECT * FROM users WHERE name = 'Joe' AND email = '[email protected]';
This can make for more readable code in complex queries.
Lastly, you can use sprintf-style % escapes in the template. This works slightly differently than the previous methods; you are responsible for ensuring that the values in the template are properly quoted. The values are passed to the connector for quoting, but the caller is responsible for ensuring they are enclosed in quotes in the resulting SQL. After quoting, the values are inserted using the same escapes as the Ruby core method Kernel::sprintf
.
User.where(["name = '%s' and email = '%s'", "Joe", "[email protected]"])
# SELECT * FROM users WHERE name = 'Joe' AND email = '[email protected]';
If #where is called with multiple arguments, these are treated as if they were passed as the elements of a single array.
User.where("name = :name and email = :email", { name: "Joe", email: "[email protected]" })
# SELECT * FROM users WHERE name = 'Joe' AND email = '[email protected]';
When using strings to specify conditions, you can use any operator available from the database. While this provides the most flexibility, you can also unintentionally introduce dependencies on the underlying database. If your code is intended for general consumption, test with multiple database backends.
hash
#where will also accept a hash condition, in which the keys are fields and the values are values to be searched for.
Fields can be symbols or strings. Values can be single values, arrays, or ranges.
User.where(name: "Joe", email: "[email protected]")
# SELECT * FROM users WHERE name = 'Joe' AND email = '[email protected]'
User.where(name: ["Alice", "Bob"])
# SELECT * FROM users WHERE name IN ('Alice', 'Bob')
User.where(created_at: (Time.now.midnight - 1.day)..Time.now.midnight)
# SELECT * FROM users WHERE (created_at BETWEEN '2012-06-09 07:00:00.000000' AND '2012-06-10 07:00:00.000000')
In the case of a belongs_to relationship, an association key can be used to specify the model if an ActiveRecord object is used as the value.
= Author.find(1)
# The following queries will be equivalent:
Post.where(author: )
Post.where(author_id: )
This also works with polymorphic belongs_to relationships:
treasure = Treasure.create(name: 'gold coins')
treasure.price_estimates << PriceEstimate.create(price: 125)
# The following queries will be equivalent:
PriceEstimate.where(estimate_of: treasure)
PriceEstimate.where(estimate_of_type: 'Treasure', estimate_of_id: treasure)
Joins
If the relation is the result of a join, you may create a condition which uses any of the tables in the join. For string and array conditions, use the table name in the condition.
User.joins(:posts).where("posts.created_at < ?", Time.now)
For hash conditions, you can either use the table name in the key, or use a sub-hash.
User.joins(:posts).where("posts.published" => true)
User.joins(:posts).where(posts: { published: true })
no argument
If no argument is passed, #where returns a new instance of WhereChain, that can be chained with WhereChain#not, WhereChain#missing, or WhereChain#associated.
Chaining with WhereChain#not:
User.where.not(name: "Jon")
# SELECT * FROM users WHERE name != 'Jon'
Chaining with WhereChain#associated:
Post.where.associated(:author)
# SELECT "posts".* FROM "posts"
# INNER JOIN "authors" ON "authors"."id" = "posts"."author_id"
# WHERE "authors"."id" IS NOT NULL
Chaining with WhereChain#missing:
Post.where.missing(:author)
# SELECT "posts".* FROM "posts"
# LEFT OUTER JOIN "authors" ON "authors"."id" = "posts"."author_id"
# WHERE "authors"."id" IS NULL
blank condition
If the condition is any blank-ish object, then #where is a no-op and returns the current relation.
763 764 765 766 767 768 769 770 771 |
# File 'lib/active_record/relation/query_methods.rb', line 763 def where(*args) if args.empty? WhereChain.new(spawn) elsif args.length == 1 && args.first.blank? self else spawn.where!(*args) end end |
#where!(opts, *rest) ⇒ Object
:nodoc:
773 774 775 776 |
# File 'lib/active_record/relation/query_methods.rb', line 773 def where!(opts, *rest) # :nodoc: self.where_clause += build_where_clause(opts, rest) self end |