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Instance Public methods

create(attributes = nil, &block)

Creates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not.

The attributes parameter can be either a Hash or an Array of Hashes. These Hashes describe the attributes on the objects that are to be created.

Examples

# Create a single new object
User.create(first_name: 'Jamie')

# Create an Array of new objects
User.create([{ first_name: 'Jamie' }, { first_name: 'Jeremy' }])

# Create a single object and pass it into a block to set other attributes.
User.create(first_name: 'Jamie') do |u|
  u.is_admin = false
end

# Creating an Array of new objects using a block, where the block is executed for each object:
User.create([{ first_name: 'Jamie' }, { first_name: 'Jeremy' }]) do |u|
  u.is_admin = false
end
# File activerecord/lib/active_record/persistence.rb, line 33
def create(attributes = nil, &block)
  if attributes.is_a?(Array)
    attributes.collect { |attr| create(attr, &block) }
  else
    object = new(attributes, &block)
    object.save
    object
  end
end

create!(attributes = nil, &block)

Creates an object (or multiple objects) and saves it to the database, if validations pass. Raises a RecordInvalid error if validations fail, unlike Base#create.

The attributes parameter can be either a Hash or an Array of Hashes. These describe which attributes to be created on the object, or multiple objects when given an Array of Hashes.

# File activerecord/lib/active_record/persistence.rb, line 50
def create!(attributes = nil, &block)
  if attributes.is_a?(Array)
    attributes.collect { |attr| create!(attr, &block) }
  else
    object = new(attributes, &block)
    object.save!
    object
  end
end

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])
# File activerecord/lib/active_record/persistence.rb, line 373
def delete(id_or_array)
  delete_by(primary_key => id_or_array)
end

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)
# File activerecord/lib/active_record/persistence.rb, line 347
def destroy(id)
  if id.is_a?(Array)
    find(id).each(&:destroy)
  else
    find(id).destroy
  end
end

insert(attributes, returning: nil, unique_by: 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 ActiveRecord::Persistence#insert_all for documentation.

# File activerecord/lib/active_record/persistence.rb, line 66
def insert(attributes, returning: nil, unique_by: nil)
  insert_all([ attributes ], returning: returning, unique_by: unique_by)
end

insert!(attributes, returning: 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 ActiveRecord::Persistence#insert_all! for more.

# File activerecord/lib/active_record/persistence.rb, line 144
def insert!(attributes, returning: nil)
  insert_all!([ attributes ], returning: returning)
end

insert_all(attributes, returning: nil, unique_by: 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 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: "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.

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" }
])
# File activerecord/lib/active_record/persistence.rb, line 134
def insert_all(attributes, returning: nil, unique_by: nil)
  InsertAll.new(self, attributes, on_duplicate: :skip, returning: returning, unique_by: unique_by).execute
end

insert_all!(attributes, returning: 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 ActiveRecord::Persistence#insert_all. To replace them, see ActiveRecord::Persistence#upsert_all.

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

Options

:returning

(PostgreSQL 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: "id, name as new_name").

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" }
])
# File activerecord/lib/active_record/persistence.rb, line 191
def insert_all!(attributes, returning: nil)
  InsertAll.new(self, attributes, on_duplicate: :raise, returning: returning).execute
end

instantiate(attributes, column_types = {}, &block)

Given an attributes hash, instantiate returns a new instance of the appropriate class. Accepts only keys as strings.

For example, Post.all may return Comments, Messages, and Emails by storing the record's subclass in a type attribute. By calling instantiate instead of new, finder methods ensure they get new instances of the appropriate class for each record.

See ActiveRecord::Inheritance#discriminate_class_for_record to see how this “single-table” inheritance mapping is implemented.

# File activerecord/lib/active_record/persistence.rb, line 278
def instantiate(attributes, column_types = {}, &block)
  klass = discriminate_class_for_record(attributes)
  instantiate_instance_of(klass, attributes, column_types, &block)
end

update(id = :all, attributes)

Updates an object (or multiple objects) and saves it to the database, if validations pass. The resulting object is returned whether the object was saved successfully to the database or not.

Parameters

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

  • attributes - This should be a hash of attributes or an array of hashes.

Examples

# Updates one record
Person.update(15, user_name: "Samuel", group: "expert")

# Updates multiple records
people = { 1 => { "first_name" => "David" }, 2 => { "first_name" => "Jeremy" } }
Person.update(people.keys, people.values)

# Updates multiple records from the result of a relation
people = Person.where(group: "expert")
people.update(group: "masters")

Note: Updating a large number of records will run an UPDATE query for each record, which may cause a performance issue. When running callbacks is not needed for each record update, it is preferred to use update_all for updating all records in a single query.

# File activerecord/lib/active_record/persistence.rb, line 309
def update(id = :all, attributes)
  if id.is_a?(Array)
    id.map { |one_id| find(one_id) }.each_with_index { |object, idx|
      object.update(attributes[idx])
    }
  elsif id == :all
    all.each { |record| record.update(attributes) }
  else
    if ActiveRecord::Base === id
      raise ArgumentError,
        "You are passing an instance of ActiveRecord::Base to `update`. " \
        "Please pass the id of the object by calling `.id`."
    end
    object = find(id)
    object.update(attributes)
    object
  end
end

upsert(attributes, on_duplicate: :update, returning: nil, unique_by: nil)

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 ActiveRecord::Persistence#upsert_all for documentation.

# File activerecord/lib/active_record/persistence.rb, line 201
def upsert(attributes, on_duplicate: :update, returning: nil, unique_by: nil)
  upsert_all([ attributes ], on_duplicate: on_duplicate, returning: returning, unique_by: unique_by)
end

upsert_all(attributes, on_duplicate: :update, returning: nil, unique_by: nil, update_sql: 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).

Options

:returning

(PostgreSQL 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: "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

Specify a custom SQL for updating rows on conflict.

NOTE: in this case you must provide all the columns you want to update by yourself.

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"
# File activerecord/lib/active_record/persistence.rb, line 264
def upsert_all(attributes, on_duplicate: :update, returning: nil, unique_by: nil, update_sql: nil)
  InsertAll.new(self, attributes, on_duplicate: on_duplicate, returning: returning, unique_by: unique_by).execute
end