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

Instance Method Details

#_select!(*fields) ⇒ Object

:nodoc:



226
227
228
229
 
# File 'lib/active_record/relation/query_methods.rb', line 226

def _select!(*fields) # :nodoc:
  self.select_values += fields.flatten
  self
end

#arel ⇒ Object

Returns the Arel object associated with the relation.



807
808
809
 
# File 'lib/active_record/relation/query_methods.rb', line 807

def arel
  @arel ||= with_default_scope.build_arel
end

#bind(value) ⇒ Object 



404
405
406
 
# File 'lib/active_record/relation/query_methods.rb', line 404

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

#bind!(value) ⇒ Object

:nodoc:



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

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

#build_arel ⇒ Object

Like #arel, but ignores the default scope of the model.



812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
 
# File 'lib/active_record/relation/query_methods.rb', line 812

def build_arel
  arel = Arel::SelectManager.new(table.engine, table)

  build_joins(arel, joins_values.flatten) unless joins_values.empty?

  collapse_wheres(arel, (where_values - ['']).uniq)

  arel.having(*having_values.uniq.reject{|h| h.blank?}) unless having_values.empty?

  arel.take(connection.sanitize_limit(limit_value)) if limit_value
  arel.skip(offset_value.to_i) if offset_value

  arel.group(*group_values.uniq.reject{|g| g.blank?}) unless group_values.empty?

  build_order(arel)

  build_select(arel, select_values.uniq)

  arel.distinct(distinct_value)
  arel.from(build_from) if from_value
  arel.lock(lock_value) if lock_value

  arel
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'



682
683
684
 
# File 'lib/active_record/relation/query_methods.rb', line 682

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

#create_with!(value) ⇒ Object

:nodoc:



686
687
688
689
690
691
692
693
694
695
 
# File 'lib/active_record/relation/query_methods.rb', line 686

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:



88
89
90
 
# File 'lib/active_record/relation/query_methods.rb', line 88

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



729
730
731
 
# File 'lib/active_record/relation/query_methods.rb', line 729

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

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

Like #distinct, but modifies relation in place.



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

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"



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

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

#eager_load!(*args) ⇒ Object

:nodoc:



139
140
141
142
 
# File 'lib/active_record/relation/query_methods.rb', line 139

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



777
778
779
780
781
782
783
 
# File 'lib/active_record/relation/query_methods.rb', line 777

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

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

:nodoc:



785
786
787
788
789
790
791
792
 
# File 'lib/active_record/relation/query_methods.rb', line 785

def extending!(*modules, &block) # :nodoc:
  modules << Module.new(&block) if block_given?

  self.extending_values += modules.flatten
  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



710
711
712
 
# File 'lib/active_record/relation/query_methods.rb', line 710

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

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

:nodoc:



714
715
716
717
 
# File 'lib/active_record/relation/query_methods.rb', line 714

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, ...>]



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

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

#group!(*args) ⇒ Object

:nodoc:



251
252
253
254
255
256
 
# File 'lib/active_record/relation/query_methods.rb', line 251

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')



560
561
562
 
# File 'lib/active_record/relation/query_methods.rb', line 560

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

#having!(opts, *rest) ⇒ Object

:nodoc:



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

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.

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)



116
117
118
119
 
# File 'lib/active_record/relation/query_methods.rb', line 116

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

#includes!(*args) ⇒ Object

:nodoc:



121
122
123
124
125
126
 
# File 'lib/active_record/relation/query_methods.rb', line 121

def includes!(*args) # :nodoc:
  args.reject! {|a| a.blank? }

  self.includes_values = (includes_values + args).flatten.uniq
  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



394
395
396
397
 
# File 'lib/active_record/relation/query_methods.rb', line 394

def joins(*args)
  check_if_method_has_arguments!("joins", args)
  spawn.joins!(*args.compact.flatten)
end

#joins!(*args) ⇒ Object

:nodoc:



399
400
401
402
 
# File 'lib/active_record/relation/query_methods.rb', line 399

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'



576
577
578
 
# File 'lib/active_record/relation/query_methods.rb', line 576

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

#limit!(value) ⇒ Object

:nodoc:



580
581
582
583
 
# File 'lib/active_record/relation/query_methods.rb', line 580

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.



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

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

#lock!(locks = true) ⇒ Object

:nodoc:



607
608
609
610
611
612
613
614
615
616
 
# File 'lib/active_record/relation/query_methods.rb', line 607

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 # => returning [] instead breaks the previous code
  end
end



646
647
648
 
# File 'lib/active_record/relation/query_methods.rb', line 646

def none
  extending(NullRelation)
end

#none! ⇒ Object

:nodoc:



650
651
652
 
# File 'lib/active_record/relation/query_methods.rb', line 650

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")



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

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

#offset!(value) ⇒ Object

:nodoc:



596
597
598
599
 
# File 'lib/active_record/relation/query_methods.rb', line 596

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



277
278
279
280
 
# File 'lib/active_record/relation/query_methods.rb', line 277

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

#order!(*args) ⇒ Object

:nodoc:



282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
 
# File 'lib/active_record/relation/query_methods.rb', line 282

def order!(*args) # :nodoc:
  args.flatten!
  validate_order_args args

  references = args.reject { |arg| Arel::Node === arg }
  references.map! { |arg| arg =~ /^([a-zA-Z]\w*)\.(\w+)/ && $1 }.compact!
  references!(references) if references.any?

  # if a symbol is given we prepend the quoted table name
  args = args.map! { |arg|
    arg.is_a?(Symbol) ?
      Arel::Nodes::Ascending.new(klass.arel_table[arg]) :
      arg
  }

  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)



148
149
150
151
 
# File 'lib/active_record/relation/query_methods.rb', line 148

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

#preload!(*args) ⇒ Object

:nodoc:



153
154
155
156
 
# File 'lib/active_record/relation/query_methods.rb', line 153

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



660
661
662
 
# File 'lib/active_record/relation/query_methods.rb', line 660

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

#readonly!(value = true) ⇒ Object

:nodoc:



664
665
666
667
 
# File 'lib/active_record/relation/query_methods.rb', line 664

def readonly!(value = true) # :nodoc:
  self.readonly_value = value
  self
end

#references(*args) ⇒ Object

Used to indicate that an association is referenced by an SQL string, and should therefore be JOINed in any query rather than loaded separately.

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



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

def references(*args)
  check_if_method_has_arguments!("references", args)
  spawn.references!(*args)
end

#references!(*args) ⇒ Object

:nodoc:



171
172
173
174
175
176
 
# File 'lib/active_record/relation/query_methods.rb', line 171

def references!(*args) # :nodoc:
  args.flatten!

  self.references_values = (references_values + args.map!(&:to_s)).uniq
  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’.



310
311
312
313
 
# File 'lib/active_record/relation/query_methods.rb', line 310

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

#reorder!(*args) ⇒ Object

:nodoc:



315
316
317
318
319
320
321
322
 
# File 'lib/active_record/relation/query_methods.rb', line 315

def reorder!(*args) # :nodoc:
  args.flatten!
  validate_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'



797
798
799
 
# File 'lib/active_record/relation/query_methods.rb', line 797

def reverse_order
  spawn.reverse_order!
end

#reverse_order! ⇒ Object

:nodoc:



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

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



217
218
219
220
221
222
223
224
 
# File 'lib/active_record/relation/query_methods.rb', line 217

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)

Note that this method is more generalized than ActiveRecord::SpawnMethods#except because #except will only affect a particular relation’s values. It won’t wipe the order, grouping, etc. when that relation is merged. For example:

Post.comments.except(:order)

will still have an order if it comes from the default_scope on Comment.



355
356
357
358
 
# File 'lib/active_record/relation/query_methods.rb', line 355

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

#unscope!(*args) ⇒ Object

:nodoc:



360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
 
# File 'lib/active_record/relation/query_methods.rb', line 360

def unscope!(*args) # :nodoc:
  args.flatten!

  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 a 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.



532
533
534
535
536
537
538
539
540
 
# File 'lib/active_record/relation/query_methods.rb', line 532

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:



542
543
544
545
546
547
548
549
550
551
552
553
554
 
# File 'lib/active_record/relation/query_methods.rb', line 542

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

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