Active Record Relation

Namespace

Module

Methods

Included Modules

Constants

CLAUSE_METHODS = [:where, :having, :from]
INVALID_METHODS_FOR_DELETE_ALL = [:distinct, :with, :with_recursive]
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]
VALUE_METHODS = MULTI_VALUE_METHODS + SINGLE_VALUE_METHODS + CLAUSE_METHODS

Attributes

[R] klass
[R] loaded
[R] loaded?
[R] model
[R] predicate_builder
[RW] skip_preloading_value
[R] table

Class Public methods

new(klass, table: klass.arel_table, predicate_builder: klass.predicate_builder, values: {})

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 77
    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
πŸ”Ž See on GitHub

Instance Public methods

==(other)

Compares two relations for equality.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1239
    def ==(other)
      case other
      when Associations::CollectionProxy, AssociationRelation
        self == other.records
      when Relation
        other.to_sql == to_sql
      when Array
        records == other
      end
    end
πŸ”Ž See on GitHub

any?(*args)

Returns true if there are any records.

When a pattern argument is given, this method checks whether elements in the Enumerable match the pattern via the case-equality operator (===).

posts.any?(Post) # => true or false
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 384
    def any?(*args)
      return false if @none

      return super if args.present? || block_given?
      !empty?
    end
πŸ”Ž See on GitHub

blank?()

Returns true if relation is blank.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1260
    def blank?
      records.blank?
    end
πŸ”Ž See on GitHub

build(attributes = nil, &block)

Alias for: new

cache_key(timestamp_column = "updated_at")

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)
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 431
    def cache_key(timestamp_column = "updated_at")
      @cache_keys ||= {}
      @cache_keys[timestamp_column] ||= klass.collection_cache_key(self, timestamp_column)
    end
πŸ”Ž See on GitHub

cache_key_with_version()

Returns a cache key along with the version.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 512
    def cache_key_with_version
      if version = cache_version
        "#{cache_key}-#{version}"
      else
        cache_key
      end
    end
πŸ”Ž See on GitHub

cache_version(timestamp_column = :updated_at)

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%')
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 458
    def cache_version(timestamp_column = :updated_at)
      if collection_cache_versioning
        @cache_versions ||= {}
        @cache_versions[timestamp_column] ||= compute_cache_version(timestamp_column)
      end
    end
πŸ”Ž See on GitHub

create(attributes = nil, &block)

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, ...>
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 147
    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
πŸ”Ž See on GitHub

create!(attributes = nil, &block)

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!.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 162
    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
πŸ”Ž See on GitHub

create_or_find_by(attributes, &block)

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).

  • Columns with unique database constraints should not have uniqueness validations defined, otherwise create will fail due to validation errors and find_by will never be called.

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.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 266
    def create_or_find_by(attributes, &block)
      with_connection do |connection|
        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
    end
πŸ”Ž See on GitHub

create_or_find_by!(attributes, &block)

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

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 281
    def create_or_find_by!(attributes, &block)
      with_connection do |connection|
        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
    end
πŸ”Ž See on GitHub

delete(id_or_array)

Deletes the row with a primary key matching the id argument, using an SQL DELETE statement, and returns the number of rows deleted. Active Record objects are not instantiated, so the object’s callbacks are not executed, including any :dependent association options.

You can delete multiple rows at once by passing an Array of ids.

Note: Although it is often much faster than the alternative, destroy, skipping callbacks might bypass business logic in your application that ensures referential integrity or performs other essential jobs.

Examples

# Delete a single row
Todo.delete(1)

# Delete multiple rows
Todo.delete([2,3,4])
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1050
    def delete(id_or_array)
      return 0 if id_or_array.nil? || (id_or_array.is_a?(Array) && id_or_array.empty?)

      where(model.primary_key => id_or_array).delete_all
    end
πŸ”Ž See on GitHub

delete_all()

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
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1004
    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

      klass.with_connection do |c|
        arel = eager_loading? ? apply_join_dependency.arel : build_arel(c)
        arel.source.left = table

        group_values_arel_columns = arel_columns(group_values.uniq)
        having_clause_ast = having_clause.ast unless having_clause.empty?
        key = if klass.composite_primary_key?
          primary_key.map { |pk| table[pk] }
        else
          table[primary_key]
        end
        stmt = arel.compile_delete(key, having_clause_ast, group_values_arel_columns)

        c.delete(stmt, "#{klass} Delete All").tap { reset }
      end
    end
πŸ”Ž See on GitHub

delete_by(*args)

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)
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1112
    def delete_by(*args)
      where(*args).delete_all
    end
πŸ”Ž See on GitHub

destroy(id)

Destroy an object (or multiple objects) that has the given id. The object is instantiated first, therefore all callbacks and filters are fired off before the object is deleted. This method is less efficient than delete but allows cleanup methods and other actions to be run.

This essentially finds the object (or multiple objects) with the given id, creates a new object from the attributes, and then calls destroy on it.

Parameters

  • id - This should be the id or an array of ids to be destroyed.

Examples

# Destroy a single object
Todo.destroy(1)

# Destroy multiple objects
todos = [1,2,3]
Todo.destroy(todos)
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1076
    def destroy(id)
      multiple_ids = if model.composite_primary_key?
        id.first.is_a?(Array)
      else
        id.is_a?(Array)
      end

      if multiple_ids
        find(id).each(&:destroy)
      else
        find(id).destroy
      end
    end
πŸ”Ž See on GitHub

destroy_all()

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
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 982
    def destroy_all
      records.each(&:destroy).tap { reset }
    end
πŸ”Ž See on GitHub

destroy_by(*args)

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)
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1099
    def destroy_by(*args)
      where(*args).destroy_all
    end
πŸ”Ž See on GitHub

eager_loading?()

Returns true if relation needs eager loading.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1224
    def eager_loading?
      @should_eager_load ||=
        eager_load_values.any? ||
        includes_values.any? && (joined_includes_values.any? || references_eager_loaded_tables?)
    end
πŸ”Ž See on GitHub

empty?()

Returns true if there are no records.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 355
    def empty?
      return true if @none

      if loaded?
        records.empty?
      else
        !exists?
      end
    end
πŸ”Ž See on GitHub

encode_with(coder)

Serializes the relation objects Array.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 341
    def encode_with(coder)
      coder.represent_seq(nil, records)
    end
πŸ”Ž See on GitHub

explain(*options)

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.

User.all.explain
# EXPLAIN SELECT `users`.* FROM `users`
# ...

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.

To run EXPLAIN on queries created by first, pluck and count, call these methods on explain:

User.all.explain.count
# EXPLAIN SELECT COUNT(*) FROM `users`
# ...

The column name can be passed if required:

User.all.explain.maximum(:id)
# EXPLAIN SELECT MAX(`users`.`id`) FROM `users`
# ...

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

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 325
    def explain(*options)
      ExplainProxy.new(self, options)
    end
πŸ”Ž See on GitHub

find_or_create_by(attributes, &block)

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 "PenΓ©lope" or create a new one.
User.find_or_create_by(first_name: 'PenΓ©lope')
# => #<User id: 1, first_name: "PenΓ©lope", last_name: nil>

# Find the first user named "PenΓ©lope" or create a new one.
# We already have one so the existing record will be returned.
User.find_or_create_by(first_name: 'PenΓ©lope')
# => #<User id: 1, first_name: "PenΓ©lope", 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 does not find a 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.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 224
    def find_or_create_by(attributes, &block)
      find_by(attributes) || create_or_find_by(attributes, &block)
    end
πŸ”Ž See on GitHub

find_or_create_by!(attributes, &block)

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

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 231
    def find_or_create_by!(attributes, &block)
      find_by(attributes) || create_or_find_by!(attributes, &block)
    end
πŸ”Ž See on GitHub

find_or_initialize_by(attributes, &block)

Like find_or_create_by, but calls new instead of create.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 295
    def find_or_initialize_by(attributes, &block)
      find_by(attributes) || new(attributes, &block)
    end
πŸ”Ž See on GitHub

initialize_copy(other)

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 90
    def initialize_copy(other)
      @values = @values.dup
      reset
    end
πŸ”Ž See on GitHub

insert(attributes, returning: nil, unique_by: nil, record_timestamps: nil)

Inserts a single record into the database in a single SQL INSERT statement. It does not instantiate any models nor does it trigger Active Record callbacks or validations. Though passed values go through Active Record’s type casting and serialization.

See insert_all for documentation.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 637
    def insert(attributes, returning: nil, unique_by: nil, record_timestamps: nil)
      insert_all([ attributes ], returning: returning, unique_by: unique_by, record_timestamps: record_timestamps)
    end
πŸ”Ž See on GitHub

insert!(attributes, returning: nil, record_timestamps: nil)

Inserts a single record into the database in a single SQL INSERT statement. It does not instantiate any models nor does it trigger Active Record callbacks or validations. Though passed values go through Active Record’s type casting and serialization.

See insert_all! for more.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 726
    def insert!(attributes, returning: nil, record_timestamps: nil)
      insert_all!([ attributes ], returning: returning, record_timestamps: record_timestamps)
    end
πŸ”Ž See on GitHub

insert_all(attributes, returning: nil, unique_by: nil, record_timestamps: nil)

Inserts multiple records into the database in a single SQL INSERT statement. It does not instantiate any models nor does it trigger Active Record callbacks or validations. Though passed values go through Active Record’s type casting and serialization.

The attributes parameter is an Array of Hashes. Every Hash determines the attributes for a single row and must have the same keys.

Rows are considered to be unique by every unique index on the table. Any duplicate rows are skipped. Override with :unique_by (see below).

Returns an ActiveRecord::Result with its contents based on :returning (see below).

Options

:returning

(PostgreSQL, SQLite3, and MariaDB only) An array of attributes to return for all successfully inserted records, which by default is the primary key. Pass returning: %w[ id name ] for both id and name or returning: false to omit the underlying RETURNING SQL clause entirely.

You can also pass an SQL string if you need more control on the return values (for example, returning: Arel.sql("id, name as new_name")).

:unique_by

(PostgreSQL and SQLite only) By default rows are considered to be unique by every unique index on the table. Any duplicate rows are skipped.

To skip rows according to just one unique index pass :unique_by.

Consider a Book model where no duplicate ISBNs make sense, but if any row has an existing id, or is not unique by another unique index, ActiveRecord::RecordNotUnique is raised.

Unique indexes can be identified by columns or name:

unique_by: :isbn
unique_by: %i[ author_id name ]
unique_by: :index_books_on_isbn
:record_timestamps

By default, automatic setting of timestamp columns is controlled by the model’s record_timestamps config, matching typical behavior.

To override this and force automatic setting of timestamp columns one way or the other, pass :record_timestamps:

record_timestamps: true  # Always set timestamps automatically
record_timestamps: false # Never set timestamps automatically

Because it relies on the index information from the database :unique_by is recommended to be paired with Active Record’s schema_cache.

Example

# Insert records and skip inserting any duplicates.
# Here "Eloquent Ruby" is skipped because its id is not unique.

Book.insert_all([
  { id: 1, title: "Rework", author: "David" },
  { id: 1, title: "Eloquent Ruby", author: "Russ" }
])

# insert_all works on chained scopes, and you can use create_with
# to set default attributes for all inserted records.

author.books.create_with(created_at: Time.now).insert_all([
  { id: 1, title: "Rework" },
  { id: 2, title: "Eloquent Ruby" }
])
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 716
    def insert_all(attributes, returning: nil, unique_by: nil, record_timestamps: nil)
      InsertAll.execute(self, attributes, on_duplicate: :skip, returning: returning, unique_by: unique_by, record_timestamps: record_timestamps)
    end
πŸ”Ž See on GitHub

insert_all!(attributes, returning: nil, record_timestamps: nil)

Inserts multiple records into the database in a single SQL INSERT statement. It does not instantiate any models nor does it trigger Active Record callbacks or validations. Though passed values go through Active Record’s type casting and serialization.

The attributes parameter is an Array of Hashes. Every Hash determines the attributes for a single row and must have the same keys.

Raises ActiveRecord::RecordNotUnique if any rows violate a unique index on the table. In that case, no rows are inserted.

To skip duplicate rows, see insert_all. To replace them, see upsert_all.

Returns an ActiveRecord::Result with its contents based on :returning (see below).

Options

:returning

(PostgreSQL, SQLite3, and MariaDB only) An array of attributes to return for all successfully inserted records, which by default is the primary key. Pass returning: %w[ id name ] for both id and name or returning: false to omit the underlying RETURNING SQL clause entirely.

You can also pass an SQL string if you need more control on the return values (for example, returning: Arel.sql("id, name as new_name")).

:record_timestamps

By default, automatic setting of timestamp columns is controlled by the model’s record_timestamps config, matching typical behavior.

To override this and force automatic setting of timestamp columns one way or the other, pass :record_timestamps:

record_timestamps: true  # Always set timestamps automatically
record_timestamps: false # Never set timestamps automatically

Examples

# Insert multiple records
Book.insert_all!([
  { title: "Rework", author: "David" },
  { title: "Eloquent Ruby", author: "Russ" }
])

# Raises ActiveRecord::RecordNotUnique because "Eloquent Ruby"
# does not have a unique id.
Book.insert_all!([
  { id: 1, title: "Rework", author: "David" },
  { id: 1, title: "Eloquent Ruby", author: "Russ" }
])
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 783
    def insert_all!(attributes, returning: nil, record_timestamps: nil)
      InsertAll.execute(self, attributes, on_duplicate: :raise, returning: returning, record_timestamps: record_timestamps)
    end
πŸ”Ž See on GitHub

inspect()

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1272
    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
πŸ”Ž See on GitHub

joined_includes_values()

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] }

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1234
    def joined_includes_values
      includes_values & joins_values
    end
πŸ”Ž See on GitHub

load(&block)

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>
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1165
    def load(&block)
      if !loaded? || scheduled?
        @records = exec_queries(&block)
        @loaded = true
      end

      self
    end
πŸ”Ž See on GitHub

load_async()

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
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1134
    def load_async
      with_connection do |c|
        return load if !c.async_enabled?

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

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

      self
    end
πŸ”Ž See on GitHub

many?()

Returns true if there is more than one record.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 406
    def many?
      return false if @none

      return super if block_given?
      return records.many? if loaded?
      limited_count > 1
    end
πŸ”Ž See on GitHub

new(attributes = nil, &block)

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
Also aliased as: build
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 118
    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
πŸ”Ž See on GitHub

none?(*args)

Returns true if there are no records.

When a pattern argument is given, this method checks whether elements in the Enumerable match the pattern via the case-equality operator (===).

posts.none?(Comment) # => true or false
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 371
    def none?(*args)
      return true if @none

      return super if args.present? || block_given?
      empty?
    end
πŸ”Ž See on GitHub

one?(*args)

Returns true if there is exactly one record.

When a pattern argument is given, this method checks whether elements in the Enumerable match the pattern via the case-equality operator (===).

posts.one?(Post) # => true or false
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 397
    def one?(*args)
      return false if @none

      return super if args.present? || block_given?
      return records.one? if loaded?
      limited_count == 1
    end
πŸ”Ž See on GitHub

pretty_print(pp)

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1250
    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
πŸ”Ž See on GitHub

reload()

Forces reloading of relation.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1175
    def reload
      reset
      load
    end
πŸ”Ž See on GitHub

reset()

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1180
    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
πŸ”Ž See on GitHub

scheduled?()

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

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1155
    def scheduled?
      !!@future_result
    end
πŸ”Ž See on GitHub

scope_for_create()

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1217
    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
πŸ”Ž See on GitHub

scoping(all_queries: nil, &block)

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.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 534
    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
πŸ”Ž See on GitHub

size()

Returns size of the records.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 346
    def size
      if loaded?
        records.length
      else
        count(:all)
      end
    end
πŸ”Ž See on GitHub

to_a()

Alias for: to_ary

to_ary()

Converts relation objects to Array.

Also aliased as: to_a
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 330
    def to_ary
      records.dup
    end
πŸ”Ž See on GitHub

to_sql()

Returns sql statement for the relation.

User.where(name: 'Oscar').to_sql
# SELECT "users".* FROM "users"  WHERE "users"."name" = 'Oscar'
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1196
    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
        klass.with_connection do |conn|
          conn.unprepared_statement { conn.to_sql(arel) }
        end
      end
    end
πŸ”Ž See on GitHub

touch_all(*names, time: nil)

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'"
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 962
    def touch_all(*names, time: nil)
      update_all klass.touch_attributes_with_time(*names, time: time)
    end
πŸ”Ž See on GitHub

update_all(updates)

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'"))
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 581
    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

      klass.with_connection do |c|
        arel = eager_loading? ? apply_join_dependency.arel : build_arel(c)
        arel.source.left = table

        group_values_arel_columns = arel_columns(group_values.uniq)
        having_clause_ast = having_clause.ast unless having_clause.empty?
        key = if klass.composite_primary_key?
          primary_key.map { |pk| table[pk] }
        else
          table[primary_key]
        end
        stmt = arel.compile_update(values, key, having_clause_ast, group_values_arel_columns)
        c.update(stmt, "#{klass} Update All").tap { reset }
      end
    end
πŸ”Ž See on GitHub

update_counters(counters)

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)
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 919
    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
πŸ”Ž See on GitHub

upsert(attributes, **kwargs)

Updates or inserts (upserts) a single record into the database in a single SQL INSERT statement. It does not instantiate any models nor does it trigger Active Record callbacks or validations. Though passed values go through Active Record’s type casting and serialization.

See upsert_all for documentation.

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 793
    def upsert(attributes, **kwargs)
      upsert_all([ attributes ], **kwargs)
    end
πŸ”Ž See on GitHub

upsert_all(attributes, on_duplicate: :update, update_only: nil, returning: nil, unique_by: nil, record_timestamps: nil)

Updates or inserts (upserts) multiple records into the database in a single SQL INSERT statement. It does not instantiate any models nor does it trigger Active Record callbacks or validations. Though passed values go through Active Record’s type casting and serialization.

The attributes parameter is an Array of Hashes. Every Hash determines the attributes for a single row and must have the same keys.

Returns an ActiveRecord::Result with its contents based on :returning (see below).

By default, upsert_all will update all the columns that can be updated when there is a conflict. These are all the columns except primary keys, read-only columns, and columns covered by the optional unique_by.

Options

:returning

(PostgreSQL, SQLite3, and MariaDB only) An array of attributes to return for all successfully inserted records, which by default is the primary key. Pass returning: %w[ id name ] for both id and name or returning: false to omit the underlying RETURNING SQL clause entirely.

You can also pass an SQL string if you need more control on the return values (for example, returning: Arel.sql("id, name as new_name")).

:unique_by

(PostgreSQL and SQLite only) By default rows are considered to be unique by every unique index on the table. Any duplicate rows are skipped.

To skip rows according to just one unique index pass :unique_by.

Consider a Book model where no duplicate ISBNs make sense, but if any row has an existing id, or is not unique by another unique index, ActiveRecord::RecordNotUnique is raised.

Unique indexes can be identified by columns or name:

unique_by: :isbn
unique_by: %i[ author_id name ]
unique_by: :index_books_on_isbn

Because it relies on the index information from the database :unique_by is recommended to be paired with Active Record’s schema_cache.

:on_duplicate

Configure the SQL update sentence that will be used in case of conflict.

NOTE: If you use this option you must provide all the columns you want to update by yourself.

Example:

Commodity.upsert_all(
  [
    { id: 2, name: "Copper", price: 4.84 },
    { id: 4, name: "Gold", price: 1380.87 },
    { id: 6, name: "Aluminium", price: 0.35 }
  ],
  on_duplicate: Arel.sql("price = GREATEST(commodities.price, EXCLUDED.price)")
)

See the related :update_only option. Both options can’t be used at the same time.

:update_only

Provide a list of column names that will be updated in case of conflict. If not provided, upsert_all will update all the columns that can be updated. These are all the columns except primary keys, read-only columns, and columns covered by the optional unique_by

Example:

Commodity.upsert_all(
  [
    { id: 2, name: "Copper", price: 4.84 },
    { id: 4, name: "Gold", price: 1380.87 },
    { id: 6, name: "Aluminium", price: 0.35 }
  ],
  update_only: [:price] # Only prices will be updated
)

See the related :on_duplicate option. Both options can’t be used at the same time.

:record_timestamps

By default, automatic setting of timestamp columns is controlled by the model’s record_timestamps config, matching typical behavior.

To override this and force automatic setting of timestamp columns one way or the other, pass :record_timestamps:

record_timestamps: true  # Always set timestamps automatically
record_timestamps: false # Never set timestamps automatically

Examples

# Inserts multiple records, performing an upsert when records have duplicate ISBNs.
# Here "Eloquent Ruby" overwrites "Rework" because its ISBN is duplicate.

Book.upsert_all([
  { title: "Rework", author: "David", isbn: "1" },
  { title: "Eloquent Ruby", author: "Russ", isbn: "1" }
], unique_by: :isbn)

Book.find_by(isbn: "1").title # => "Eloquent Ruby"
πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 903
    def upsert_all(attributes, on_duplicate: :update, update_only: nil, returning: nil, unique_by: nil, record_timestamps: nil)
      InsertAll.execute(self, attributes, on_duplicate: on_duplicate, update_only: update_only, returning: returning, unique_by: unique_by, record_timestamps: record_timestamps)
    end
πŸ”Ž See on GitHub

values()

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1264
    def values
      @values.dup
    end
πŸ”Ž See on GitHub

Instance Protected methods

load_records(records)

πŸ“ Source code
# File activerecord/lib/active_record/relation.rb, line 1313
      def load_records(records)
        @records = records.freeze
        @loaded = true
      end
πŸ”Ž See on GitHub