Class: ActiveRecord::Relation

Inherits:
Object
  • Object
show all
Includes:
Batches, Calculations, Delegation, Explain, FinderMethods, QueryMethods, RecordFetchWarning, SpawnMethods, Enumerable
Defined in:
lib/active_record/relation.rb,
lib/active_record/relation/merger.rb,
lib/active_record/relation/from_clause.rb,
lib/active_record/relation/where_clause.rb,
lib/active_record/relation/query_attribute.rb,
lib/active_record/relation/record_fetch_warning.rb

Overview

Active Record Relation

Defined Under Namespace

Modules: RecordFetchWarning Classes: FromClause, HashMerger, Merger, QueryAttribute, StrictLoadingScope, WhereClause

Constant Summary collapse

MULTI_VALUE_METHODS = 
[:includes, :eager_load, :preload, :select, :group,
:order, :joins, :left_outer_joins, :references,
:extending, :unscope, :optimizer_hints, :annotate,
:with]
SINGLE_VALUE_METHODS = 
[:limit, :offset, :lock, :readonly, :reordering, :strict_loading,
:reverse_order, :distinct, :create_with, :skip_query_cache]
CLAUSE_METHODS = 
[:where, :having, :from]
INVALID_METHODS_FOR_DELETE_ALL = 
[:distinct, :with]
VALUE_METHODS = 
MULTI_VALUE_METHODS + SINGLE_VALUE_METHODS + CLAUSE_METHODS

Constants included from FinderMethods

FinderMethods::ONE_AS_ONE

Constants included from QueryMethods

QueryMethods::FROZEN_EMPTY_ARRAY, QueryMethods::FROZEN_EMPTY_HASH, QueryMethods::VALID_UNSCOPING_VALUES

Constants included from Batches

Batches::DEFAULT_ORDER, Batches::ORDER_IGNORE_MESSAGE

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from FinderMethods

#exists?, #fifth, #fifth!, #find, #find_by, #find_by!, #find_sole_by, #first, #first!, #forty_two, #forty_two!, #fourth, #fourth!, #include?, #last, #last!, #raise_record_not_found_exception!, #second, #second!, #second_to_last, #second_to_last!, #sole, #take, #take!, #third, #third!, #third_to_last, #third_to_last!

Methods included from Calculations

#async_average, #async_count, #async_ids, #async_maximum, #async_minimum, #async_pick, #async_pluck, #async_sum, #average, #calculate, #count, #ids, #maximum, #minimum, #pick, #pluck, #sum

Methods included from SpawnMethods

#except, #merge, #merge!, #only, #spawn

Methods included from QueryMethods

#_select!, #and, #and!, #annotate, #annotate!, #arel, #construct_join_dependency, #create_with, #create_with!, #distinct, #distinct!, #eager_load, #eager_load!, #excluding, #excluding!, #extending, #extending!, #extract_associated, #from, #from!, #group, #group!, #having, #having!, #in_order_of, #includes, #includes!, #invert_where, #invert_where!, #joins, #joins!, #left_outer_joins, #left_outer_joins!, #limit, #limit!, #lock, #lock!, #none, #none!, #null_relation?, #offset, #offset!, #optimizer_hints, #optimizer_hints!, #or, #or!, #order, #order!, #preload, #preload!, #readonly, #readonly!, #references, #references!, #regroup, #regroup!, #reorder, #reorder!, #reselect, #reselect!, #reverse_order, #reverse_order!, #rewhere, #select, #skip_preloading!, #skip_query_cache!, #strict_loading, #strict_loading!, #structurally_compatible?, #uniq!, #unscope, #unscope!, #where, #where!, #with, #with!

Methods included from Batches

#find_each, #find_in_batches, #in_batches

Methods included from Explain

#collecting_queries_for_explain, #exec_explain

Methods included from Delegation

delegated_classes, uncacheable_methods

Constructor Details

#initialize(klass, table: klass.arel_table, predicate_builder: klass.predicate_builder, values: {}) ⇒ Relation

Returns a new instance of Relation.



28
29
30
31
32
33
34
35
36
37
38
39
 
# File 'lib/active_record/relation.rb', line 28

def initialize(klass, table: klass.arel_table, predicate_builder: klass.predicate_builder, values: {})
  @klass  = klass
  @table  = table
  @values = values
  @loaded = false
  @predicate_builder = predicate_builder
  @delegate_to_klass = false
  @future_result = nil
  @records = nil
  @async = false
  @none = false
end

Instance Attribute Details

#klass ⇒ Object (readonly) Also known as: model

Returns the value of attribute klass.



22
23
24
 
# File 'lib/active_record/relation.rb', line 22

def klass
  @klass
end

#loaded ⇒ Object (readonly) Also known as: loaded?

Returns the value of attribute loaded.



22
23
24
 
# File 'lib/active_record/relation.rb', line 22

def loaded
  @loaded
end

#predicate_builder ⇒ Object (readonly)

Returns the value of attribute predicate_builder.



22
23
24
 
# File 'lib/active_record/relation.rb', line 22

def predicate_builder
  @predicate_builder
end

#skip_preloading_value ⇒ Object

Returns the value of attribute skip_preloading_value.



23
24
25
 
# File 'lib/active_record/relation.rb', line 23

def skip_preloading_value
  @skip_preloading_value
end

#table ⇒ Object (readonly)

Returns the value of attribute table.



22
23
24
 
# File 'lib/active_record/relation.rb', line 22

def table
  @table
end

Instance Method Details

#==(other) ⇒ Object

Compares two relations for equality.



798
799
800
801
802
803
804
805
806
807
 
# File 'lib/active_record/relation.rb', line 798

def ==(other)
  case other
  when Associations::CollectionProxy, AssociationRelation
    self == other.records
  when Relation
    other.to_sql == to_sql
  when Array
    records == other
  end
end

#_exec_scope ⇒ Object

:nodoc:



456
457
458
459
460
461
462
 
# File 'lib/active_record/relation.rb', line 456

def _exec_scope(...) # :nodoc:
  @delegate_to_klass = true
  registry = klass.scope_registry
  _scoping(nil, registry) { instance_exec(...) || self }
ensure
  @delegate_to_klass = false
end

#alias_tracker(joins = [], aliases = nil) ⇒ Object

:nodoc:



848
849
850
 
# File 'lib/active_record/relation.rb', line 848

def alias_tracker(joins = [], aliases = nil) # :nodoc:
  ActiveRecord::Associations::AliasTracker.create(connection, table.name, joins, aliases)
end

#any?(*args) ⇒ Boolean

Returns true if there are any records.

Returns:

  • (Boolean) 


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

def any?(*args)
  return false if @none

  return super if args.present? || block_given?
  !empty?
end

#bind_attribute(name, value) {|attr, bind| ... } ⇒ Object

:nodoc:

Yields:

  • (attr, bind) 


46
47
48
49
50
51
52
53
54
55
 
# File 'lib/active_record/relation.rb', line 46

def bind_attribute(name, value) # :nodoc:
  if reflection = klass._reflect_on_association(name)
    name = reflection.foreign_key
    value = value.read_attribute(reflection.association_primary_key) unless value.nil?
  end

  attr = table[name]
  bind = predicate_builder.build_bind_attribute(attr.name, value)
  yield attr, bind
end

#blank? ⇒ Boolean

Returns true if relation is blank.

Returns:

  • (Boolean) 


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

def blank?
  records.blank?
end

#cache_key(timestamp_column = "updated_at") ⇒ Object

Returns a stable cache key that can be used to identify this query. The cache key is built with a fingerprint of the SQL query.

Product.where("name like ?", "%Cosmic Encounter%").cache_key
# => "products/query-1850ab3d302391b85b8693e941286659"

If ActiveRecord::Base.collection_cache_versioning is turned off, as it was in Rails 6.0 and earlier, the cache key will also include a version.

ActiveRecord::Base.collection_cache_versioning = false
Product.where("name like ?", "%Cosmic Encounter%").cache_key
# => "products/query-1850ab3d302391b85b8693e941286659-1-20150714212553907087000"

You can also pass a custom timestamp column to fetch the timestamp of the last updated record.

Product.where("name like ?", "%Game%").cache_key(:last_reviewed_at)



344
345
346
347
 
# File 'lib/active_record/relation.rb', line 344

def cache_key(timestamp_column = "updated_at")
  @cache_keys ||= {}
  @cache_keys[timestamp_column] ||= klass.collection_cache_key(self, timestamp_column)
end

#cache_key_with_version ⇒ Object

Returns a cache key along with the version.



423
424
425
426
427
428
429
 
# File 'lib/active_record/relation.rb', line 423

def cache_key_with_version
  if version = cache_version
    "#{cache_key}-#{version}"
  else
    cache_key
  end
end

#cache_version(timestamp_column = :updated_at) ⇒ Object

Returns a cache version that can be used together with the cache key to form a recyclable caching scheme. The cache version is built with the number of records matching the query, and the timestamp of the last updated record. When a new record comes to match the query, or any of the existing records is updated or deleted, the cache version changes.

If the collection is loaded, the method will iterate through the records to generate the timestamp, otherwise it will trigger one SQL query like:

SELECT COUNT(*), MAX("products"."updated_at") FROM "products" WHERE (name like '%Cosmic Encounter%')



371
372
373
374
375
376
 
# File 'lib/active_record/relation.rb', line 371

def cache_version(timestamp_column = :updated_at)
  if collection_cache_versioning
    @cache_versions ||= {}
    @cache_versions[timestamp_column] ||= compute_cache_version(timestamp_column)
  end
end

#create(attributes = nil, &block) ⇒ Object

Tries to create a new record with the same scoped attributes defined in the relation. Returns the initialized object if validation fails.

Expects arguments in the same format as ActiveRecord::Base.create.

Examples

users = User.where(name: 'Oscar')
users.create # => #<User id: 3, name: "Oscar", ...>

users.create(name: 'fxn')
users.create # => #<User id: 4, name: "fxn", ...>

users.create { |user| user.name = 'tenderlove' }
# => #<User id: 5, name: "tenderlove", ...>

users.create(name: nil) # validation on name
# => #<User id: nil, name: nil, ...>



98
99
100
101
102
103
104
105
 
# File 'lib/active_record/relation.rb', line 98

def create(attributes = nil, &block)
  if attributes.is_a?(Array)
    attributes.collect { |attr| create(attr, &block) }
  else
    block = current_scope_restoring_block(&block)
    scoping { _create(attributes, &block) }
  end
end

#create!(attributes = nil, &block) ⇒ Object

Similar to #create, but calls create! on the base class. Raises an exception if a validation error occurs.

Expects arguments in the same format as ActiveRecord::Base.create!.



113
114
115
116
117
118
119
120
 
# File 'lib/active_record/relation.rb', line 113

def create!(attributes = nil, &block)
  if attributes.is_a?(Array)
    attributes.collect { |attr| create!(attr, &block) }
  else
    block = current_scope_restoring_block(&block)
    scoping { _create!(attributes, &block) }
  end
end

#create_or_find_by(attributes, &block) ⇒ Object

Attempts to create a record with the given attributes in a table that has a unique database constraint on one or several of its columns. If a row already exists with one or several of these unique constraints, the exception such an insertion would normally raise is caught, and the existing record with those attributes is found using #find_by!.

This is similar to #find_or_create_by, but tries to create the record first. As such it is better suited for cases where the record is most likely not to exist yet.

There are several drawbacks to #create_or_find_by, though:

  • The underlying table must have the relevant columns defined with unique database constraints.

  • A unique constraint violation may be triggered by only one, or at least less than all, of the given attributes. This means that the subsequent #find_by! may fail to find a matching record, which will then raise an ActiveRecord::RecordNotFound exception, rather than a record with the given attributes.

  • While we avoid the race condition between SELECT -> INSERT from #find_or_create_by, we actually have another race condition between INSERT -> SELECT, which can be triggered if a DELETE between those two statements is run by another client. But for most applications, that’s a significantly less likely condition to hit.

  • It relies on exception handling to handle control flow, which may be marginally slower.

  • The primary key may auto-increment on each create, even if it fails. This can accelerate the problem of running out of integers, if the underlying table is still stuck on a primary key of type int (note: All Rails apps since 5.1+ have defaulted to bigint, which is not liable to this problem).

This method will return a record if all given attributes are covered by unique constraints (unless the INSERT -> DELETE -> SELECT race condition is triggered), but if creation was attempted and failed due to validation errors it won’t be persisted, you get what #create returns in such situation.



215
216
217
218
219
220
221
222
223
 
# File 'lib/active_record/relation.rb', line 215

def create_or_find_by(attributes, &block)
  transaction(requires_new: true) { create(attributes, &block) }
rescue ActiveRecord::RecordNotUnique
  if connection.transaction_open?
    where(attributes).lock.find_by!(attributes)
  else
    find_by!(attributes)
  end
end

#create_or_find_by!(attributes, &block) ⇒ Object

Like #create_or_find_by, but calls create! so an exception is raised if the created record is invalid.



228
229
230
231
232
233
234
235
236
 
# File 'lib/active_record/relation.rb', line 228

def create_or_find_by!(attributes, &block)
  transaction(requires_new: true) { create!(attributes, &block) }
rescue ActiveRecord::RecordNotUnique
  if connection.transaction_open?
    where(attributes).lock.find_by!(attributes)
  else
    find_by!(attributes)
  end
end

#delete_all ⇒ Object

Deletes the records without instantiating the records first, and hence not calling the #destroy method nor invoking callbacks. This is a single SQL DELETE statement that goes straight to the database, much more efficient than #destroy_all. Be careful with relations though, in particular :dependent rules defined on associations are not honored. Returns the number of rows affected.

Post.where(person_id: 5).where(category: ['Something', 'Else']).delete_all

Both calls delete the affected posts all at once with a single DELETE statement. If you need to destroy dependent associations or call your before_* or after_destroy callbacks, use the #destroy_all method instead.

If an invalid method is supplied, #delete_all raises an ActiveRecordError:

Post.distinct.delete_all
# => ActiveRecord::ActiveRecordError: delete_all doesn't support distinct



631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
 
# File 'lib/active_record/relation.rb', line 631

def delete_all
  return 0 if @none

  invalid_methods = INVALID_METHODS_FOR_DELETE_ALL.select do |method|
    value = @values[method]
    method == :distinct ? value : value&.any?
  end
  if invalid_methods.any?
    raise ActiveRecordError.new("delete_all doesn't support #{invalid_methods.join(', ')}")
  end

  arel = eager_loading? ? apply_join_dependency.arel : build_arel
  arel.source.left = table

  group_values_arel_columns = arel_columns(group_values.uniq)
  having_clause_ast = having_clause.ast unless having_clause.empty?
  stmt = arel.compile_delete(table[primary_key], having_clause_ast, group_values_arel_columns)

  klass.connection.delete(stmt, "#{klass} Delete All").tap { reset }
end

#delete_by(*args) ⇒ Object

Finds and deletes all records matching the specified conditions. This is short-hand for relation.where(condition).delete_all. Returns the number of rows affected.

If no record is found, returns 0 as zero rows were affected.

Person.delete_by(id: 13)
Person.delete_by(name: 'Spartacus', rating: 4)
Person.delete_by("published_at < ?", 2.weeks.ago)



674
675
676
 
# File 'lib/active_record/relation.rb', line 674

def delete_by(*args)
  where(*args).delete_all
end

#destroy_all ⇒ Object

Destroys the records by instantiating each record and calling its #destroy method. Each object’s callbacks are executed (including :dependent association options). Returns the collection of objects that were destroyed; each will be frozen, to reflect that no changes should be made (since they can’t be persisted).

Note: Instantiation, callback execution, and deletion of each record can be time consuming when you’re removing many records at once. It generates at least one SQL DELETE query per record (or possibly more, to enforce your callbacks). If you want to delete many rows quickly, without concern for their associations or callbacks, use #delete_all instead.

Examples

Person.where(age: 0..18).destroy_all



609
610
611
 
# File 'lib/active_record/relation.rb', line 609

def destroy_all
  records.each(&:destroy).tap { reset }
end

#destroy_by(*args) ⇒ Object

Finds and destroys all records matching the specified conditions. This is short-hand for relation.where(condition).destroy_all. Returns the collection of objects that were destroyed.

If no record is found, returns empty array.

Person.destroy_by(id: 13)
Person.destroy_by(name: 'Spartacus', rating: 4)
Person.destroy_by("published_at < ?", 2.weeks.ago)



661
662
663
 
# File 'lib/active_record/relation.rb', line 661

def destroy_by(*args)
  where(*args).destroy_all
end

#eager_loading? ⇒ Boolean

Returns true if relation needs eager loading.

Returns:

  • (Boolean) 


783
784
785
786
787
 
# File 'lib/active_record/relation.rb', line 783

def eager_loading?
  @should_eager_load ||=
    eager_load_values.any? ||
    includes_values.any? && (joined_includes_values.any? || references_eager_loaded_tables?)
end

#empty? ⇒ Boolean

Returns true if there are no records.

Returns:

  • (Boolean) 


283
284
285
286
287
288
289
290
291
 
# File 'lib/active_record/relation.rb', line 283

def empty?
  return true if @none

  if loaded?
    records.empty?
  else
    !exists?
  end
end

#empty_scope? ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


840
841
842
 
# File 'lib/active_record/relation.rb', line 840

def empty_scope? # :nodoc:
  @values == klass.unscoped.values
end

#encode_with(coder) ⇒ Object

Serializes the relation objects Array.



269
270
271
 
# File 'lib/active_record/relation.rb', line 269

def encode_with(coder)
  coder.represent_seq(nil, records)
end

#explain(*options) ⇒ Object

Runs EXPLAIN on the query or queries triggered by this relation and returns the result as a string. The string is formatted imitating the ones printed by the database shell.

Note that this method actually runs the queries, since the results of some are needed by the next ones when eager loading is going on.

Please see further details in the Active Record Query Interface guide.



253
254
255
 
# File 'lib/active_record/relation.rb', line 253

def explain(*options)
  exec_explain(collecting_queries_for_explain { exec_queries }, options)
end

#find_or_create_by(attributes, &block) ⇒ Object

Finds the first record with the given attributes, or creates a record with the attributes if one is not found:

# Find the first user named "Penélope" or create a new one.
User.find_or_create_by(first_name: 'Penélope')
# => #<User id: 1, first_name: "Penélope", last_name: nil>

# Find the first user named "Penélope" or create a new one.
# We already have one so the existing record will be returned.
User.find_or_create_by(first_name: 'Penélope')
# => #<User id: 1, first_name: "Penélope", last_name: nil>

# Find the first user named "Scarlett" or create a new one with
# a particular last name.
User.create_with(last_name: 'Johansson').find_or_create_by(first_name: 'Scarlett')
# => #<User id: 2, first_name: "Scarlett", last_name: "Johansson">

This method accepts a block, which is passed down to #create. The last example above can be alternatively written this way:

# Find the first user named "Scarlett" or create a new one with a
# particular last name.
User.find_or_create_by(first_name: 'Scarlett') do |user|
  user.last_name = 'Johansson'
end
# => #<User id: 2, first_name: "Scarlett", last_name: "Johansson">

This method always returns a record, but if creation was attempted and failed due to validation errors it won’t be persisted, you get what #create returns in such situation.

If creation failed because of a unique constraint, this method will assume it encountered a race condition and will try finding the record once more If somehow the second find still find no record because a concurrent DELETE happened, it will then raise an ActiveRecord::RecordNotFound exception.

Please note this method is not atomic, it runs first a SELECT, and if there are no results an INSERT is attempted. So if the table doesn’t have a relevant unique constraint it could be the case that you end up with two or more similar records.



175
176
177
 
# File 'lib/active_record/relation.rb', line 175

def find_or_create_by(attributes, &block)
  find_by(attributes) || create_or_find_by(attributes, &block)
end

#find_or_create_by!(attributes, &block) ⇒ Object

Like #find_or_create_by, but calls create! so an exception is raised if the created record is invalid.



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

def find_or_create_by!(attributes, &block)
  find_by(attributes) || create_or_find_by!(attributes, &block)
end

#find_or_initialize_by(attributes, &block) ⇒ Object

Like #find_or_create_by, but calls new instead of create.



240
241
242
 
# File 'lib/active_record/relation.rb', line 240

def find_or_initialize_by(attributes, &block)
  find_by(attributes) || new(attributes, &block)
end

#first_or_create(attributes = nil, &block) ⇒ Object

:nodoc:



122
123
124
 
# File 'lib/active_record/relation.rb', line 122

def first_or_create(attributes = nil, &block) # :nodoc:
  first || create(attributes, &block)
end

#first_or_create!(attributes = nil, &block) ⇒ Object

:nodoc:



126
127
128
 
# File 'lib/active_record/relation.rb', line 126

def first_or_create!(attributes = nil, &block) # :nodoc:
  first || create!(attributes, &block)
end

#first_or_initialize(attributes = nil, &block) ⇒ Object

:nodoc:



130
131
132
 
# File 'lib/active_record/relation.rb', line 130

def first_or_initialize(attributes = nil, &block) # :nodoc:
  first || new(attributes, &block)
end

#has_limit_or_offset? ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


844
845
846
 
# File 'lib/active_record/relation.rb', line 844

def has_limit_or_offset? # :nodoc:
  limit_value || offset_value
end

#initialize_copy(other) ⇒ Object 



41
42
43
44
 
# File 'lib/active_record/relation.rb', line 41

def initialize_copy(other)
  @values = @values.dup
  reset
end

#inspect ⇒ Object 



831
832
833
834
835
836
837
838
 
# File 'lib/active_record/relation.rb', line 831

def inspect
  subject = loaded? ? records : annotate("loading for inspect")
  entries = subject.take([limit_value, 11].compact.min).map!(&:inspect)

  entries[10] = "..." if entries.size == 11

  "#<#{self.class.name} [#{entries.join(', ')}]>"
end

#joined_includes_values ⇒ Object

Joins that are also marked for preloading. In which case we should just eager load them. Note that this is a naive implementation because we could have strings and symbols which represent the same association, but that aren’t matched by this. Also, we could have nested hashes which partially match, e.g. { a: :b } & { a: [:b, :c] }



793
794
795
 
# File 'lib/active_record/relation.rb', line 793

def joined_includes_values
  includes_values & joins_values
end

#load(&block) ⇒ Object

Causes the records to be loaded from the database if they have not been loaded already. You can use this if for some reason you need to explicitly load some records before actually using them. The return value is the relation itself, not the records.

Post.where(published: true).load # => #<ActiveRecord::Relation>



725
726
727
728
729
730
731
732
 
# File 'lib/active_record/relation.rb', line 725

def load(&block)
  if !loaded? || scheduled?
    @records = exec_queries(&block)
    @loaded = true
  end

  self
end

#load_async ⇒ Object

Schedule the query to be performed from a background thread pool.

Post.where(published: true).load_async # => #<ActiveRecord::Relation>

When the Relation is iterated, if the background query wasn’t executed yet, it will be performed by the foreground thread.

Note that config.active_record.async_query_executor must be configured for queries to actually be executed concurrently. Otherwise it defaults to executing them in the foreground.

load_async will also fall back to executing in the foreground in the test environment when transactional fixtures are enabled.

If the query was actually executed in the background, the Active Record logs will show it by prefixing the log line with ASYNC:

ASYNC Post Load (0.0ms) (db time 2ms)  SELECT "posts".* FROM "posts" LIMIT 100



696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
 
# File 'lib/active_record/relation.rb', line 696

def load_async
  return load if !connection.async_enabled?

  unless loaded?
    result = exec_main_query(async: connection.current_transaction.closed?)

    if result.is_a?(Array)
      @records = result
    else
      @future_result = result
    end
    @loaded = true
  end

  self
end

#many? ⇒ Boolean

Returns true if there is more than one record.

Returns:

  • (Boolean) 


319
320
321
322
323
324
325
 
# File 'lib/active_record/relation.rb', line 319

def many?
  return false if @none

  return super if block_given?
  return records.many? if loaded?
  limited_count > 1
end

#new(attributes = nil, &block) ⇒ Object Also known as: build

Initializes new record from relation while maintaining the current scope.

Expects arguments in the same format as ActiveRecord::Base.new.

users = User.where(name: 'DHH')
user = users.new # => #<User id: nil, name: "DHH", created_at: nil, updated_at: nil>

You can also pass a block to new with the new record as argument:

user = users.new { |user| user.name = 'Oscar' }
user.name # => Oscar



69
70
71
72
73
74
75
76
 
# File 'lib/active_record/relation.rb', line 69

def new(attributes = nil, &block)
  if attributes.is_a?(Array)
    attributes.collect { |attr| new(attr, &block) }
  else
    block = current_scope_restoring_block(&block)
    scoping { _new(attributes, &block) }
  end
end

#none?(*args) ⇒ Boolean

Returns true if there are no records.

Returns:

  • (Boolean) 


294
295
296
297
298
299
 
# File 'lib/active_record/relation.rb', line 294

def none?(*args)
  return true if @none

  return super if args.present? || block_given?
  empty?
end

#one?(*args) ⇒ Boolean

Returns true if there is exactly one record.

Returns:

  • (Boolean) 


310
311
312
313
314
315
316
 
# File 'lib/active_record/relation.rb', line 310

def one?(*args)
  return false if @none

  return super if args.present? || block_given?
  return records.one? if loaded?
  limited_count == 1
end

#preload_associations(records) ⇒ Object

:nodoc:



862
863
864
865
866
867
868
869
 
# File 'lib/active_record/relation.rb', line 862

def preload_associations(records) # :nodoc:
  preload = preload_values
  preload += includes_values unless eager_loading?
  scope = strict_loading_value ? StrictLoadingScope : nil
  preload.each do |associations|
    ActiveRecord::Associations::Preloader.new(records: records, associations: associations, scope: scope).call
  end
end

#pretty_print(pp) ⇒ Object 



809
810
811
812
813
814
815
816
 
# File 'lib/active_record/relation.rb', line 809

def pretty_print(pp)
  subject = loaded? ? records : annotate("loading for pp")
  entries = subject.take([limit_value, 11].compact.min)

  entries[10] = "..." if entries.size == 11

  pp.pp(entries)
end

#records ⇒ Object

:nodoc:



263
264
265
266
 
# File 'lib/active_record/relation.rb', line 263

def records # :nodoc:
  load
  @records
end

#reload ⇒ Object

Forces reloading of relation.



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

def reload
  reset
  load
end

#reset ⇒ Object 



740
741
742
743
744
745
746
747
748
749
750
 
# File 'lib/active_record/relation.rb', line 740

def reset
  @future_result&.cancel
  @future_result = nil
  @delegate_to_klass = false
  @to_sql = @arel = @loaded = @should_eager_load = nil
  @offsets = @take = nil
  @cache_keys = nil
  @cache_versions = nil
  @records = nil
  self
end

#scheduled? ⇒ Boolean

Returns true if the relation was scheduled on the background thread pool.

Returns:

  • (Boolean) 


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

def scheduled?
  !!@future_result
end

#scope_for_create ⇒ Object 



776
777
778
779
780
 
# File 'lib/active_record/relation.rb', line 776

def scope_for_create
  hash = where_clause.to_h(klass.table_name, equality_only: true)
  create_with_value.each { |k, v| hash[k.to_s] = v } unless create_with_value.empty?
  hash
end

#scoping(all_queries: nil, &block) ⇒ Object

Scope all queries to the current scope.

Comment.where(post_id: 1).scoping do
  Comment.first
end
# SELECT "comments".* FROM "comments" WHERE "comments"."post_id" = 1 ORDER BY "comments"."id" ASC LIMIT 1

If all_queries: true is passed, scoping will apply to all queries for the relation including update and delete on instances. Once all_queries is set to true it cannot be set to false in a nested block.

Please check unscoped if you want to remove all previous scopes (including the default_scope) during the execution of a block.



445
446
447
448
449
450
451
452
453
454
 
# File 'lib/active_record/relation.rb', line 445

def scoping(all_queries: nil, &block)
  registry = klass.scope_registry
  if global_scope?(registry) && all_queries == false
    raise ArgumentError, "Scoping is set to apply to all queries and cannot be unset in a nested block."
  elsif already_in_scope?(registry)
    yield
  else
    _scoping(self, registry, all_queries, &block)
  end
end

#size ⇒ Object

Returns size of the records.



274
275
276
277
278
279
280
 
# File 'lib/active_record/relation.rb', line 274

def size
  if loaded?
    records.length
  else
    count(:all)
  end
end

#to_ary ⇒ Object Also known as: to_a

Converts relation objects to Array.



258
259
260
 
# File 'lib/active_record/relation.rb', line 258

def to_ary
  records.dup
end

#to_sql ⇒ Object

Returns sql statement for the relation.

User.where(name: 'Oscar').to_sql
# SELECT "users".* FROM "users"  WHERE "users"."name" = 'Oscar'



756
757
758
759
760
761
762
763
764
765
766
 
# File 'lib/active_record/relation.rb', line 756

def to_sql
  @to_sql ||= if eager_loading?
    apply_join_dependency do |relation, join_dependency|
      relation = join_dependency.apply_column_aliases(relation)
      relation.to_sql
    end
  else
    conn = klass.connection
    conn.unprepared_statement { conn.to_sql(arel) }
  end
end

#touch_all(*names, time: nil) ⇒ Object

Touches all records in the current relation, setting the updated_at/updated_on attributes to the current time or the time specified. It does not instantiate the involved models, and it does not trigger Active Record callbacks or validations. This method can be passed attribute names and an optional time argument. If attribute names are passed, they are updated along with updated_at/updated_on attributes. If no time argument is passed, the current time is used as default.

Examples

# Touch all records
Person.all.touch_all
# => "UPDATE \"people\" SET \"updated_at\" = '2018-01-04 22:55:23.132670'"

# Touch multiple records with a custom attribute
Person.all.touch_all(:created_at)
# => "UPDATE \"people\" SET \"updated_at\" = '2018-01-04 22:55:23.132670', \"created_at\" = '2018-01-04 22:55:23.132670'"

# Touch multiple records with a specified time
Person.all.touch_all(time: Time.new(2020, 5, 16, 0, 0, 0))
# => "UPDATE \"people\" SET \"updated_at\" = '2020-05-16 00:00:00'"

# Touch records with scope
Person.where(name: 'David').touch_all
# => "UPDATE \"people\" SET \"updated_at\" = '2018-01-04 22:55:23.132670' WHERE \"people\".\"name\" = 'David'"



589
590
591
 
# File 'lib/active_record/relation.rb', line 589

def touch_all(*names, time: nil)
  update_all klass.touch_attributes_with_time(*names, time: time)
end

#update(id = :all, attributes) ⇒ Object

:nodoc:



518
519
520
521
522
523
524
 
# File 'lib/active_record/relation.rb', line 518

def update(id = :all, attributes) # :nodoc:
  if id == :all
    each { |record| record.update(attributes) }
  else
    klass.update(id, attributes)
  end
end

#update!(id = :all, attributes) ⇒ Object

:nodoc:



526
527
528
529
530
531
532
 
# File 'lib/active_record/relation.rb', line 526

def update!(id = :all, attributes) # :nodoc:
  if id == :all
    each { |record| record.update!(attributes) }
  else
    klass.update!(id, attributes)
  end
end

#update_all(updates) ⇒ Object

Updates all records in the current relation with details given. This method constructs a single SQL UPDATE statement and sends it straight to the database. It does not instantiate the involved models and it does not trigger Active Record callbacks or validations. However, values passed to #update_all will still go through Active Record’s normal type casting and serialization. Returns the number of rows affected.

Note: As Active Record callbacks are not triggered, this method will not automatically update updated_at/updated_on columns.

Parameters

  • updates - A string, array, or hash representing the SET part of an SQL statement. Any strings provided will be type cast, unless you use Arel.sql. (Don’t pass user-provided values to Arel.sql.)

Examples

# Update all customers with the given attributes
Customer.update_all wants_email: true

# Update all books with 'Rails' in their title
Book.where('title LIKE ?', '%Rails%').update_all(author: 'David')

# Update all books that match conditions, but limit it to 5 ordered by date
Book.where('title LIKE ?', '%Rails%').order(:created_at).limit(5).update_all(author: 'David')

# Update all invoices and set the number column to its id value.
Invoice.update_all('number = id')

# Update all books with 'Rails' in their title
Book.where('title LIKE ?', '%Rails%').update_all(title: Arel.sql("title + ' - volume 1'"))

Raises:

  • (ArgumentError) 


492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
 
# File 'lib/active_record/relation.rb', line 492

def update_all(updates)
  raise ArgumentError, "Empty list of attributes to change" if updates.blank?

  return 0 if @none

  if updates.is_a?(Hash)
    if klass.locking_enabled? &&
        !updates.key?(klass.locking_column) &&
        !updates.key?(klass.locking_column.to_sym)
      attr = table[klass.locking_column]
      updates[attr.name] = _increment_attribute(attr)
    end
    values = _substitute_values(updates)
  else
    values = Arel.sql(klass.sanitize_sql_for_assignment(updates, table.name))
  end

  arel = eager_loading? ? apply_join_dependency.arel : build_arel
  arel.source.left = table

  group_values_arel_columns = arel_columns(group_values.uniq)
  having_clause_ast = having_clause.ast unless having_clause.empty?
  stmt = arel.compile_update(values, table[primary_key], having_clause_ast, group_values_arel_columns)
  klass.connection.update(stmt, "#{klass} Update All").tap { reset }
end

#update_counters(counters) ⇒ Object

Updates the counters of the records in the current relation.

Parameters

  • counter - A Hash containing the names of the fields to update as keys and the amount to update as values.

  • :touch option - Touch the timestamp columns when updating.

  • If attributes names are passed, they are updated along with update_at/on attributes.

Examples

# For Posts by a given author increment the comment_count by 1.
Post.where(author_id: author.id).update_counters(comment_count: 1)



546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
 
# File 'lib/active_record/relation.rb', line 546

def update_counters(counters)
  touch = counters.delete(:touch)

  updates = {}
  counters.each do |counter_name, value|
    attr = table[counter_name]
    updates[attr.name] = _increment_attribute(attr, value)
  end

  if touch
    names = touch if touch != true
    names = Array.wrap(names)
    options = names.extract_options!
    touch_updates = klass.touch_attributes_with_time(*names, **options)
    updates.merge!(touch_updates) unless touch_updates.empty?
  end

  update_all updates
end

#values ⇒ Object 



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

def values
  @values.dup
end

#values_for_queries ⇒ Object

:nodoc:



827
828
829
 
# File 'lib/active_record/relation.rb', line 827

def values_for_queries # :nodoc:
  @values.except(:extending, :skip_query_cache, :strict_loading)
end

#where_values_hash(relation_table_name = klass.table_name) ⇒ Object

Returns a hash of where conditions.

User.where(name: 'Oscar').where_values_hash
# => {name: "Oscar"}



772
773
774
 
# File 'lib/active_record/relation.rb', line 772

def where_values_hash(relation_table_name = klass.table_name) # :nodoc:
  where_clause.to_h(relation_table_name)
end