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:
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# File 'lib/active_record/relation/query_methods.rb', line 310 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)
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# File 'lib/active_record/relation/query_methods.rb', line 824 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:
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# File 'lib/active_record/relation/query_methods.rb', line 832 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.
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# File 'lib/active_record/relation/query_methods.rb', line 1198 def annotate(*args) check_if_method_has_arguments!(__callee__, args) spawn.annotate!(*args) end |
#annotate!(*args) ⇒ Object
Like #annotate, but modifies relation in place.
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# File 'lib/active_record/relation/query_methods.rb', line 1204 def annotate!(*args) # :nodoc: self.annotate_values += args self end |
#arel(aliases = nil) ⇒ Object
Returns the Arel object associated with the relation.
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# File 'lib/active_record/relation/query_methods.rb', line 1259 def arel(aliases = nil) # :nodoc: @arel ||= build_arel(aliases) end |
#construct_join_dependency(associations, join_type) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 1263 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'
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# File 'lib/active_record/relation/query_methods.rb', line 1017 def create_with(value) spawn.create_with!(value) end |
#create_with!(value) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 1021 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
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# File 'lib/active_record/relation/query_methods.rb', line 1081 def distinct(value = true) spawn.distinct!(value) end |
#distinct!(value = true) ⇒ Object
Like #distinct, but modifies relation in place.
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# File 'lib/active_record/relation/query_methods.rb', line 1086 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"
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# File 'lib/active_record/relation/query_methods.rb', line 200 def eager_load(*args) check_if_method_has_arguments!(__callee__, args) spawn.eager_load!(*args) end |
#eager_load!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 205 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.
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# File 'lib/active_record/relation/query_methods.rb', line 1240 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:
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# File 'lib/active_record/relation/query_methods.rb', line 1252 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
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# File 'lib/active_record/relation/query_methods.rb', line 1127 def extending(*modules, &block) if modules.any? || block spawn.extending!(*modules, &block) else self end end |
#extending!(*modules, &block) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 1135 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)
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# File 'lib/active_record/relation/query_methods.rb', line 233 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')
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# File 'lib/active_record/relation/query_methods.rb', line 1062 def from(value, subquery_name = nil) spawn.from!(value, subquery_name) end |
#from!(value, subquery_name = nil) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 1066 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">]
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# File 'lib/active_record/relation/query_methods.rb', line 356 def group(*args) check_if_method_has_arguments!(__callee__, args) spawn.group!(*args) end |
#group!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 361 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')
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# File 'lib/active_record/relation/query_methods.rb', line 882 def having(opts, *rest) opts.blank? ? self : spawn.having!(opts, *rest) end |
#having!(opts, *rest) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 886 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. Depending on your adapter this will either use a CASE statement or a built-in function.
User.in_order_of(:id, [1, 5, 3])
# SELECT "users".* FROM "users"
# ORDER BY FIELD("users"."id", 1, 5, 3)
# WHERE "users"."id" IN (1, 5, 3)
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# File 'lib/active_record/relation/query_methods.rb', line 440 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 spawn .order!(connection.field_ordered_value(arel_column, values)) .where!(arel_column.in(values)) 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' })
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# File 'lib/active_record/relation/query_methods.rb', line 184 def includes(*args) check_if_method_has_arguments!(__callee__, args) spawn.includes!(*args) end |
#includes!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 189 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)
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# File 'lib/active_record/relation/query_methods.rb', line 790 def invert_where spawn.invert_where! end |
#invert_where! ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 794 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
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# File 'lib/active_record/relation/query_methods.rb', line 579 def joins(*args) check_if_method_has_arguments!(__callee__, args) spawn.joins!(*args) end |
#joins!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 584 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"
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# File 'lib/active_record/relation/query_methods.rb', line 594 def left_outer_joins(*args) check_if_method_has_arguments!(__callee__, args) spawn.left_outer_joins!(*args) end |
#left_outer_joins!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 600 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'
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# File 'lib/active_record/relation/query_methods.rb', line 896 def limit(value) spawn.limit!(value) end |
#limit!(value) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 900 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.
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# File 'lib/active_record/relation/query_methods.rb', line 923 def lock(locks = true) spawn.lock!(locks) end |
#lock!(locks = true) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 927 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
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# File 'lib/active_record/relation/query_methods.rb', line 966 def none spawn.none! end |
#none! ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 970 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")
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# File 'lib/active_record/relation/query_methods.rb', line 912 def offset(value) spawn.offset!(value) end |
#offset!(value) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 916 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"
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# File 'lib/active_record/relation/query_methods.rb', line 1156 def optimizer_hints(*args) check_if_method_has_arguments!(__callee__, args) spawn.optimizer_hints!(*args) end |
#optimizer_hints!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 1161 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))
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# File 'lib/active_record/relation/query_methods.rb', line 856 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:
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# File 'lib/active_record/relation/query_methods.rb', line 864 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'
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# File 'lib/active_record/relation/query_methods.rb', line 418 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.
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# File 'lib/active_record/relation/query_methods.rb', line 426 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)
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# File 'lib/active_record/relation/query_methods.rb', line 214 def preload(*args) check_if_method_has_arguments!(__callee__, args) spawn.preload!(*args) end |
#preload!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 219 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
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# File 'lib/active_record/relation/query_methods.rb', line 980 def readonly(value = true) spawn.readonly!(value) end |
#readonly!(value = true) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 984 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
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# File 'lib/active_record/relation/query_methods.rb', line 247 def references(*table_names) check_if_method_has_arguments!(__callee__, table_names) spawn.references!(*table_names) end |
#references!(*table_names) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 252 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’.
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# File 'lib/active_record/relation/query_methods.rb', line 464 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.
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# File 'lib/active_record/relation/query_methods.rb', line 472 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.
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# File 'lib/active_record/relation/query_methods.rb', line 325 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.
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# File 'lib/active_record/relation/query_methods.rb', line 331 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'
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# File 'lib/active_record/relation/query_methods.rb', line 1169 def reverse_order spawn.reverse_order! end |
#reverse_order! ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 1173 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.
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# File 'lib/active_record/relation/query_methods.rb', line 752 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: "value", other_field: "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
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# File 'lib/active_record/relation/query_methods.rb', line 297 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:
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# File 'lib/active_record/relation/query_methods.rb', line 1184 def skip_preloading! # :nodoc: self.skip_preloading_value = true self end |
#skip_query_cache!(value = true) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 1179 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
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# File 'lib/active_record/relation/query_methods.rb', line 995 def strict_loading(value = true) spawn.strict_loading!(value) end |
#strict_loading!(value = true) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 999 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
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# File 'lib/active_record/relation/query_methods.rb', line 810 def structurally_compatible?(other) structurally_incompatible_values_for(other).empty? end |
#uniq!(name) ⇒ Object
Deduplicate multiple values.
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# File 'lib/active_record/relation/query_methods.rb', line 1210 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) }
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# File 'lib/active_record/relation/query_methods.rb', line 517 def unscope(*args) check_if_method_has_arguments!(__callee__, args) spawn.unscope!(*args) end |
#unscope!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 522 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 #not to return a new relation that negates the where clause.
User.where.not(name: "Jon")
# SELECT * FROM users WHERE name != 'Jon'
See WhereChain for more details on #not.
blank condition
If the condition is any blank-ish object, then #where is a no-op and returns the current relation.
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# File 'lib/active_record/relation/query_methods.rb', line 724 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:
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# File 'lib/active_record/relation/query_methods.rb', line 734 def where!(opts, *rest) # :nodoc: self.where_clause += build_where_clause(opts, rest) self end |