Module: ActiveRecord::QueryMethods

Extended by:
ActiveSupport::Concern
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

Instance Method Details

#_select!(*fields) ⇒ Object

:nodoc:



242
243
244
245
246
247
248
249
 
# File 'lib/active_record/relation/query_methods.rb', line 242

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.



829
830
831
 
# File 'lib/active_record/relation/query_methods.rb', line 829

def arel # :nodoc:
  @arel ||= build_arel
end

#bind(value) ⇒ Object 



422
423
424
 
# File 'lib/active_record/relation/query_methods.rb', line 422

def bind(value)
  spawn.bind!(value)
end

#bind!(value) ⇒ Object

:nodoc:



426
427
428
429
 
# File 'lib/active_record/relation/query_methods.rb', line 426

def bind!(value) # :nodoc:
  self.bind_values += [value]
  self
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'



709
710
711
 
# File 'lib/active_record/relation/query_methods.rb', line 709

def create_with(value)
  spawn.create_with!(value)
end

#create_with!(value) ⇒ Object

:nodoc:



713
714
715
716
 
# File 'lib/active_record/relation/query_methods.rb', line 713

def create_with!(value) # :nodoc:
  self.create_with_value = value ? create_with_value.merge(value) : {}
  self
end

#create_with_value ⇒ Object

:nodoc:



89
90
91
 
# File 'lib/active_record/relation/query_methods.rb', line 89

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



750
751
752
 
# File 'lib/active_record/relation/query_methods.rb', line 750

def distinct(value = true)
  spawn.distinct!(value)
end

#distinct!(value = true) ⇒ Object Also known as: uniq!

Like #distinct, but modifies relation in place.



756
757
758
759
 
# File 'lib/active_record/relation/query_methods.rb', line 756

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"



147
148
149
150
 
# File 'lib/active_record/relation/query_methods.rb', line 147

def eager_load(*args)
  check_if_method_has_arguments!(:eager_load, args)
  spawn.eager_load!(*args)
end

#eager_load!(*args) ⇒ Object

:nodoc:



152
153
154
155
 
# File 'lib/active_record/relation/query_methods.rb', line 152

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



798
799
800
801
802
803
804
 
# File 'lib/active_record/relation/query_methods.rb', line 798

def extending(*modules, &block)
  if modules.any? || block
    spawn.extending!(*modules, &block)
  else
    self
  end
end

#extending!(*modules, &block) ⇒ Object

:nodoc:



806
807
808
809
810
811
812
813
814
 
# File 'lib/active_record/relation/query_methods.rb', line 806

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



731
732
733
 
# File 'lib/active_record/relation/query_methods.rb', line 731

def from(value, subquery_name = nil)
  spawn.from!(value, subquery_name)
end

#from!(value, subquery_name = nil) ⇒ Object

:nodoc:



735
736
737
738
 
# File 'lib/active_record/relation/query_methods.rb', line 735

def from!(value, subquery_name = nil) # :nodoc:
  self.from_value = [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, ...>]



266
267
268
269
 
# File 'lib/active_record/relation/query_methods.rb', line 266

def group(*args)
  check_if_method_has_arguments!(:group, args)
  spawn.group!(*args)
end

#group!(*args) ⇒ Object

:nodoc:



271
272
273
274
275
276
 
# File 'lib/active_record/relation/query_methods.rb', line 271

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')



587
588
589
 
# File 'lib/active_record/relation/query_methods.rb', line 587

def having(opts, *rest)
  opts.blank? ? self : spawn.having!(opts, *rest)
end

#having!(opts, *rest) ⇒ Object

:nodoc:



591
592
593
594
595
596
 
# File 'lib/active_record/relation/query_methods.rb', line 591

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.



128
129
130
131
 
# File 'lib/active_record/relation/query_methods.rb', line 128

def includes(*args)
  check_if_method_has_arguments!(:includes, args)
  spawn.includes!(*args)
end

#includes!(*args) ⇒ Object

:nodoc:



133
134
135
136
137
138
139
 
# File 'lib/active_record/relation/query_methods.rb', line 133

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



408
409
410
411
412
413
414
415
 
# File 'lib/active_record/relation/query_methods.rb', line 408

def joins(*args)
  check_if_method_has_arguments!(:joins, args)

  args.compact!
  args.flatten!

  spawn.joins!(*args)
end

#joins!(*args) ⇒ Object

:nodoc:



417
418
419
420
 
# File 'lib/active_record/relation/query_methods.rb', line 417

def joins!(*args) # :nodoc:
  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'



603
604
605
 
# File 'lib/active_record/relation/query_methods.rb', line 603

def limit(value)
  spawn.limit!(value)
end

#limit!(value) ⇒ Object

:nodoc:



607
608
609
610
 
# File 'lib/active_record/relation/query_methods.rb', line 607

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.



630
631
632
 
# File 'lib/active_record/relation/query_methods.rb', line 630

def lock(locks = true)
  spawn.lock!(locks)
end

#lock!(locks = true) ⇒ Object

:nodoc:



634
635
636
637
638
639
640
641
642
643
 
# File 'lib/active_record/relation/query_methods.rb', line 634

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



673
674
675
 
# File 'lib/active_record/relation/query_methods.rb', line 673

def none
  extending(NullRelation)
end

#none! ⇒ Object

:nodoc:



677
678
679
 
# File 'lib/active_record/relation/query_methods.rb', line 677

def none! # :nodoc:
  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")



619
620
621
 
# File 'lib/active_record/relation/query_methods.rb', line 619

def offset(value)
  spawn.offset!(value)
end

#offset!(value) ⇒ Object

:nodoc:



623
624
625
626
 
# File 'lib/active_record/relation/query_methods.rb', line 623

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 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

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



297
298
299
300
 
# File 'lib/active_record/relation/query_methods.rb', line 297

def order(*args)
  check_if_method_has_arguments!(:order, args)
  spawn.order!(*args)
end

#order!(*args) ⇒ Object

:nodoc:



302
303
304
305
306
307
 
# File 'lib/active_record/relation/query_methods.rb', line 302

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)



161
162
163
164
 
# File 'lib/active_record/relation/query_methods.rb', line 161

def preload(*args)
  check_if_method_has_arguments!(:preload, args)
  spawn.preload!(*args)
end

#preload!(*args) ⇒ Object

:nodoc:



166
167
168
169
 
# File 'lib/active_record/relation/query_methods.rb', line 166

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



687
688
689
 
# File 'lib/active_record/relation/query_methods.rb', line 687

def readonly(value = true)
  spawn.readonly!(value)
end

#readonly!(value = true) ⇒ Object

:nodoc:



691
692
693
694
 
# File 'lib/active_record/relation/query_methods.rb', line 691

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 conjuction 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



181
182
183
184
 
# File 'lib/active_record/relation/query_methods.rb', line 181

def references(*table_names)
  check_if_method_has_arguments!(:references, table_names)
  spawn.references!(*table_names)
end

#references!(*table_names) ⇒ Object

:nodoc:



186
187
188
189
190
191
192
 
# File 'lib/active_record/relation/query_methods.rb', line 186

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’.



318
319
320
321
 
# File 'lib/active_record/relation/query_methods.rb', line 318

def reorder(*args)
  check_if_method_has_arguments!(:reorder, args)
  spawn.reorder!(*args)
end

#reorder!(*args) ⇒ Object

:nodoc:



323
324
325
326
327
328
329
 
# File 'lib/active_record/relation/query_methods.rb', line 323

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'



819
820
821
 
# File 'lib/active_record/relation/query_methods.rb', line 819

def reverse_order
  spawn.reverse_order!
end

#reverse_order! ⇒ Object

:nodoc:



823
824
825
826
 
# File 'lib/active_record/relation/query_methods.rb', line 823

def reverse_order! # :nodoc:
  self.reverse_order_value = !reverse_order_value
  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.



579
580
581
 
# File 'lib/active_record/relation/query_methods.rb', line 579

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 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 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 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 will throw ActiveModel::MissingAttributeError:

Model.select(:field).first.other_field
# => ActiveModel::MissingAttributeError: missing attribute: other_field



233
234
235
236
237
238
239
240
 
# File 'lib/active_record/relation/query_methods.rb', line 233

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 }



368
369
370
371
 
# File 'lib/active_record/relation/query_methods.rb', line 368

def unscope(*args)
  check_if_method_has_arguments!(:unscope, args)
  spawn.unscope!(*args)
end

#unscope!(*args) ⇒ Object

:nodoc:



373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
 
# File 'lib/active_record/relation/query_methods.rb', line 373

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 = Author.find(1)

# The following queries will be equivalent:
Post.where(author: author)
Post.where(author_id: author)

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.



550
551
552
553
554
555
556
557
558
 
# File 'lib/active_record/relation/query_methods.rb', line 550

def where(opts = :chain, *rest)
  if opts == :chain
    WhereChain.new(spawn)
  elsif opts.blank?
    self
  else
    spawn.where!(opts, *rest)
  end
end

#where!(opts = :chain, *rest) ⇒ Object

:nodoc:



560
561
562
563
564
565
566
567
568
569
 
# File 'lib/active_record/relation/query_methods.rb', line 560

def where!(opts = :chain, *rest) # :nodoc:
  if opts == :chain
    WhereChain.new(self)
  else
    references!(PredicateBuilder.references(opts)) if Hash === opts

    self.where_values += build_where(opts, rest)
    self
  end
end