Module: ActiveRecord::Persistence::ClassMethods

Defined in:
lib/active_record/persistence.rb

Instance Method Summary collapse

Instance Method Details

#_delete_record(constraints) ⇒ Object

:nodoc:



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# File 'lib/active_record/persistence.rb', line 200

def _delete_record(constraints) # :nodoc:
  constraints = _substitute_values(constraints).map { |attr, bind| attr.eq(bind) }

  dm = Arel::DeleteManager.new
  dm.from(arel_table)
  dm.wheres = constraints

  connection.delete(dm, "#{self} Destroy")
end

#_insert_record(values) ⇒ Object

:nodoc:



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# File 'lib/active_record/persistence.rb', line 168

def _insert_record(values) # :nodoc:
  primary_key_value = nil

  if primary_key && Hash === values
    primary_key_value = values[primary_key]

    if !primary_key_value && prefetch_primary_key?
      primary_key_value = next_sequence_value
      values[primary_key] = primary_key_value
    end
  end

  if values.empty?
    im = arel_table.compile_insert(connection.empty_insert_statement_value)
    im.into arel_table
  else
    im = arel_table.compile_insert(_substitute_values(values))
  end

  connection.insert(im, "#{self} Create", primary_key || false, primary_key_value)
end

#_update_record(values, constraints) ⇒ Object

:nodoc:



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# File 'lib/active_record/persistence.rb', line 190

def _update_record(values, constraints) # :nodoc:
  constraints = _substitute_values(constraints).map { |attr, bind| attr.eq(bind) }

  um = arel_table.where(
    constraints.reduce(&:and)
  ).compile_update(_substitute_values(values), primary_key)

  connection.update(um, "#{self} Update")
end

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

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



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# File 'lib/active_record/persistence.rb', line 31

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) ⇒ Object

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.



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# File 'lib/active_record/persistence.rb', line 48

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) ⇒ Object

Deletes the row with a primary key matching the id argument, using a 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])



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# File 'lib/active_record/persistence.rb', line 164

def delete(id_or_array)
  where(primary_key => id_or_array).delete_all
end

#destroy(id) ⇒ Object

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)



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# File 'lib/active_record/persistence.rb', line 138

def destroy(id)
  if id.is_a?(Array)
    find(id).each(&:destroy)
  else
    find(id).destroy
  end
end

#instantiate(attributes, column_types = {}, &block) ⇒ Object

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.



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# File 'lib/active_record/persistence.rb', line 68

def instantiate(attributes, column_types = {}, &block)
  klass = discriminate_class_for_record(attributes)
  attributes = klass.attributes_builder.build_from_database(attributes, column_types)
  klass.allocate.init_with("attributes" => attributes, "new_record" => false, &block)
end

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

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.



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# File 'lib/active_record/persistence.rb', line 100

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