Module: ActiveRecord::QueryMethods
- Extended by:
- ActiveSupport::Concern
- Includes:
- ActiveModel::ForbiddenAttributesProtection
- Included in:
- Relation
- Defined in:
- lib/active_record/relation/query_methods.rb
Defined Under Namespace
Classes: WhereChain
Constant Summary collapse
- VALID_UNSCOPING_VALUES =
Set.new([:where, :select, :group, :order, :lock, :limit, :offset, :joins, :includes, :from, :readonly, :having])
Instance Method Summary collapse
-
#_select!(*fields) ⇒ Object
:nodoc:.
-
#arel ⇒ Object
Returns the Arel object associated with the relation.
-
#bind(value) ⇒ Object
:nodoc:.
-
#bind!(value) ⇒ Object
:nodoc:.
-
#check_cached_relation ⇒ Object
:nodoc:.
-
#create_with(value) ⇒ Object
Sets attributes to be used when creating new records from a relation object.
-
#create_with!(value) ⇒ Object
:nodoc:.
-
#create_with_value ⇒ Object
:nodoc:.
-
#distinct(value = true) ⇒ Object
(also: #uniq)
Specifies whether the records should be unique or not.
-
#distinct!(value = true) ⇒ Object
(also: #uniq!)
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:.
-
#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:.
-
#from(value, subquery_name = nil) ⇒ Object
Specifies 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:.
-
#includes(*args) ⇒ Object
Specify relationships to be included in the result set.
-
#includes!(*args) ⇒ Object
:nodoc:.
-
#joins(*args) ⇒ Object
Performs a joins on
args
:. -
#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:.
-
#order(*args) ⇒ Object
Allows to specify an order attribute:.
-
#order!(*args) ⇒ Object
:nodoc:.
-
#preload(*args) ⇒ Object
Allows preloading of
args
, in the same way thatincludes
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
:nodoc:.
-
#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.
-
#unscope(*args) ⇒ Object
Removes an unwanted relation that is already defined on a chain of relations.
-
#unscope!(*args) ⇒ Object
:nodoc:.
-
#where(opts = :chain, *rest) ⇒ 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 258 def _select!(*fields) # :nodoc: fields.flatten! fields.map! do |field| klass.attribute_alias?(field) ? klass.attribute_alias(field) : field end self.select_values += fields self end |
#arel ⇒ Object
Returns the Arel object associated with the relation.
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# File 'lib/active_record/relation/query_methods.rb', line 857 def arel # :nodoc: @arel ||= build_arel end |
#bind(value) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 440 def bind(value) # :nodoc: spawn.bind!(value) end |
#bind!(value) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 444 def bind!(value) # :nodoc: self.bind_values += [value] self end |
#check_cached_relation ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 95 def check_cached_relation # :nodoc: if defined?(@arel) && @arel @arel = nil ActiveSupport::Deprecation.warn(<<-MSG.squish) Modifying already cached Relation. The cache will be reset. Use a cloned Relation to prevent this warning. MSG end 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 726 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 730 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 = {} end self end |
#create_with_value ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 105 def create_with_value # :nodoc: @values[:create_with] || {} end |
#distinct(value = true) ⇒ Object Also known as: uniq
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 776 def distinct(value = true) spawn.distinct!(value) end |
#distinct!(value = true) ⇒ Object Also known as: uniq!
Like #distinct, but modifies relation in place.
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# File 'lib/active_record/relation/query_methods.rb', line 782 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 163 def eager_load(*args) check_if_method_has_arguments!(:eager_load, args) spawn.eager_load!(*args) end |
#eager_load!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 168 def eager_load!(*args) # :nodoc: self.eager_load_values += args 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 824 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 832 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 |
#from(value, subquery_name = nil) ⇒ Object
Specifies 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
Topic.select('a.title').from(Topic.approved, :a)
# => SELECT a.title FROM (SELECT * FROM topics WHERE approved = 't') a
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# File 'lib/active_record/relation/query_methods.rb', line 754 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 758 def from!(value, subquery_name = nil) # :nodoc: self.from_value = [value, subquery_name] if value.is_a? Relation self.bind_values = value.arel.bind_values + value.bind_values + bind_values end 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 286 def group(*args) check_if_method_has_arguments!(:group, args) spawn.group!(*args) end |
#group!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 291 def group!(*args) # :nodoc: args.flatten! 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 604 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 608 def having!(opts, *rest) # :nodoc: references!(PredicateBuilder.references(opts)) if Hash === opts self.having_values += build_where(opts, rest) self 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 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.
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# File 'lib/active_record/relation/query_methods.rb', line 144 def includes(*args) check_if_method_has_arguments!(:includes, args) spawn.includes!(*args) end |
#includes!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 149 def includes!(*args) # :nodoc: args.reject!(&:blank?) args.flatten! self.includes_values |= args self end |
#joins(*args) ⇒ Object
Performs a joins on args
:
User.joins(:posts)
=> SELECT "users".* FROM "users" INNER JOIN "posts" ON "posts"."user_id" = "users"."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 428 def joins(*args) check_if_method_has_arguments!(:joins, args) spawn.joins!(*args) end |
#joins!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 433 def joins!(*args) # :nodoc: args.compact! args.flatten! self.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 620 def limit(value) spawn.limit!(value) end |
#limit!(value) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 624 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 647 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 651 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 690 def none where("1=0").extending!(NullRelation) end |
#none! ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 694 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 636 def offset(value) spawn.offset!(value) end |
#offset!(value) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 640 def offset!(value) # :nodoc: self.offset_value = value self end |
#order(*args) ⇒ Object
Allows to specify an order attribute:
User.order(:name)
=> SELECT "users".* FROM "users" ORDER BY "users"."name" ASC
User.order(email: :desc)
=> SELECT "users".* FROM "users" ORDER BY "users"."email" DESC
User.order(:name, email: :desc)
=> SELECT "users".* FROM "users" ORDER BY "users"."name" ASC, "users"."email" DESC
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
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# File 'lib/active_record/relation/query_methods.rb', line 317 def order(*args) check_if_method_has_arguments!(:order, args) spawn.order!(*args) end |
#order!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 322 def order!(*args) # :nodoc: preprocess_order_args(args) 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 177 def preload(*args) check_if_method_has_arguments!(:preload, args) spawn.preload!(*args) end |
#preload!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 182 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: ActiveRecord::ReadOnlyRecord
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# File 'lib/active_record/relation/query_methods.rb', line 704 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 708 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 197 def references(*table_names) check_if_method_has_arguments!(:references, 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 202 def references!(*table_names) # :nodoc: table_names.flatten! table_names.map!(&:to_s) 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 338 def reorder(*args) check_if_method_has_arguments!(:reorder, args) spawn.reorder!(*args) end |
#reorder!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 343 def reorder!(*args) # :nodoc: preprocess_order_args(args) self.reordering_value = true self.order_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 845 def reverse_order spawn.reverse_order! end |
#reverse_order! ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 849 def reverse_order! # :nodoc: orders = order_values.uniq orders.reject!(&: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 596 def rewhere(conditions) unscope(where: conditions.keys).where(conditions) 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 249 def select(*fields) if block_given? to_a.select { |*block_args| yield(*block_args) } else raise ArgumentError, 'Call this with at least one field' if fields.empty? spawn._select!(*fields) end 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 388 def unscope(*args) check_if_method_has_arguments!(:unscope, args) spawn.unscope!(*args) end |
#unscope!(*args) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 393 def unscope!(*args) # :nodoc: args.flatten! self.unscope_values += args args.each do |scope| case scope when Symbol symbol_unscoping(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 Array(target_value).each do |val| where_unscoping(val) end end else raise ArgumentError, "Unrecognized scoping: #{args.inspect}. Use .unscope(where: :attribute_name) or .unscope(:order), for example." end end self end |
#where(opts = :chain, *rest) ⇒ 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 568 def where(opts = :chain, *rest) if opts == :chain WhereChain.new(spawn) elsif opts.blank? self else spawn.where!(opts, *rest) end end |
#where!(opts, *rest) ⇒ Object
:nodoc:
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# File 'lib/active_record/relation/query_methods.rb', line 578 def where!(opts, *rest) # :nodoc: if Hash === opts opts = sanitize_forbidden_attributes(opts) references!(PredicateBuilder.references(opts)) end self.where_values += build_where(opts, rest) self end |