module ActiveRecord::Core
Active Record Core¶ ↑
Attributes
Public Class Methods
Source
# File lib/active_record/core.rb, line 119 class_attribute :attributes_for_inspect, instance_accessor: false, default: :all
Specifies the attributes that will be included in the output of the inspect
method:
Post.attributes_for_inspect = [:id, :title] Post.first.inspect #=> "#<Post id: 1, title: "Hello, World!">"
When set to ‘:all` inspect will list all the record’s attributes:
Post.attributes_for_inspect = :all Post.first.inspect #=> "#<Post id: 1, title: "Hello, World!", published_at: "2023-10-23 14:28:11 +0000">"
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# File lib/active_record/core.rb, line 77 def self.configurations @@configurations end
Returns a fully resolved ActiveRecord::DatabaseConfigurations
object.
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# File lib/active_record/core.rb, line 71 def self.configurations=(config) @@configurations = ActiveRecord::DatabaseConfigurations.new(config) end
Contains the database configuration - as is typically stored in config/database.yml - as an ActiveRecord::DatabaseConfigurations
object.
For example, the following database.yml…
development: adapter: sqlite3 database: storage/development.sqlite3 production: adapter: sqlite3 database: storage/production.sqlite3
…would result in ActiveRecord::Base.configurations
to look like this:
#<ActiveRecord::DatabaseConfigurations:0x00007fd1acbdf800 @configurations=[ #<ActiveRecord::DatabaseConfigurations::HashConfig:0x00007fd1acbded10 @env_name="development", @name="primary", @config={adapter: "sqlite3", database: "storage/development.sqlite3"}>, #<ActiveRecord::DatabaseConfigurations::HashConfig:0x00007fd1acbdea90 @env_name="production", @name="primary", @config={adapter: "sqlite3", database: "storage/production.sqlite3"}> ]>
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# File lib/active_record/core.rb, line 133 def self.connection_handler ActiveSupport::IsolatedExecutionState[:active_record_connection_handler] || default_connection_handler end
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# File lib/active_record/core.rb, line 137 def self.connection_handler=(handler) ActiveSupport::IsolatedExecutionState[:active_record_connection_handler] = handler end
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# File lib/active_record/core.rb, line 196 def self.current_preventing_writes connected_to_stack.reverse_each do |hash| return hash[:prevent_writes] if !hash[:prevent_writes].nil? && hash[:klasses].include?(Base) return hash[:prevent_writes] if !hash[:prevent_writes].nil? && hash[:klasses].include?(connection_class_for_self) end false end
Returns the symbol representing the current setting for preventing writes.
ActiveRecord::Base.connected_to(role: :reading) do ActiveRecord::Base.current_preventing_writes #=> true end ActiveRecord::Base.connected_to(role: :writing) do ActiveRecord::Base.current_preventing_writes #=> false end
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# File lib/active_record/core.rb, line 159 def self.current_role connected_to_stack.reverse_each do |hash| return hash[:role] if hash[:role] && hash[:klasses].include?(Base) return hash[:role] if hash[:role] && hash[:klasses].include?(connection_class_for_self) end default_role end
Returns the symbol representing the current connected role.
ActiveRecord::Base.connected_to(role: :writing) do ActiveRecord::Base.current_role #=> :writing end ActiveRecord::Base.connected_to(role: :reading) do ActiveRecord::Base.current_role #=> :reading end
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# File lib/active_record/core.rb, line 177 def self.current_shard connected_to_stack.reverse_each do |hash| return hash[:shard] if hash[:shard] && hash[:klasses].include?(Base) return hash[:shard] if hash[:shard] && hash[:klasses].include?(connection_class_for_self) end default_shard end
Returns the symbol representing the current connected shard.
ActiveRecord::Base.connected_to(role: :reading) do ActiveRecord::Base.current_shard #=> :default end ActiveRecord::Base.connected_to(role: :writing, shard: :one) do ActiveRecord::Base.current_shard #=> :one end
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# File lib/active_record/core.rb, line 47 class_attribute :destroy_association_async_batch_size, instance_writer: false, instance_predicate: false, default: nil
Specifies the maximum number of records that will be destroyed in a single background job by the dependent: :destroy_async
association option. When nil
(default), all dependent records will be destroyed in a single background job. If specified, the records to be destroyed will be split into multiple background jobs.
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# File lib/active_record/core.rb, line 27 def self.destroy_association_async_job if _destroy_association_async_job.is_a?(String) self._destroy_association_async_job = _destroy_association_async_job.constantize end _destroy_association_async_job rescue NameError => error raise NameError, "Unable to load destroy_association_async_job: #{error.message}" end
The job class used to destroy associations in the background.
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# File lib/active_record/core.rb, line 87 class_attribute :enumerate_columns_in_select_statements, instance_accessor: false, default: false
Force enumeration of all columns in SELECT statements. e.g. SELECT first_name, last_name FROM ...
instead of SELECT * FROM ...
This avoids PreparedStatementCacheExpired
errors when a column is added to the database while the app is running.
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# File lib/active_record/core.rb, line 22 class_attribute :logger, instance_writer: false
Accepts a logger conforming to the interface of Log4r or the default Ruby Logger
class, which is then passed on to any new database connections made. You can retrieve this logger by calling logger
on either an Active Record model class or an Active Record model instance.
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# File lib/active_record/core.rb, line 460 def initialize(attributes = nil) @new_record = true @attributes = self.class._default_attributes.deep_dup init_internals initialize_internals_callback super yield self if block_given? _run_initialize_callbacks end
New objects can be instantiated as either empty (pass no construction parameter) or pre-set with attributes but not yet saved (pass a hash with key names matching the associated table column names). In both instances, valid attribute keys are determined by the column names of the associated table – hence you can’t have attributes that aren’t part of the table columns.
Example¶ ↑
# Instantiates a single new object User.new(first_name: 'Jamie')
Public Instance Methods
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# File lib/active_record/core.rb, line 654 def <=>(other_object) if other_object.is_a?(self.class) to_key <=> other_object.to_key else super end end
Allows sort on objects
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# File lib/active_record/core.rb, line 620 def ==(comparison_object) super || comparison_object.instance_of?(self.class) && primary_key_values_present? && comparison_object.id == id end
Returns true if comparison_object
is the same exact object, or comparison_object
is of the same type and self
has an ID and it is equal to comparison_object.id
.
Note that new records are different from any other record by definition, unless the other record is the receiver itself. Besides, if you fetch existing records with select
and leave the ID out, you’re on your own, this predicate will return false.
Note also that destroying a record preserves its ID in the model instance, so deleted models are still comparable.
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# File lib/active_record/core.rb, line 512
Identical to Ruby’s clone method. This is a “shallow” copy. Be warned that your attributes are not copied. That means that modifying attributes of the clone will modify the original, since they will both point to the same attributes hash. If you need a copy of your attributes hash, please use the dup
method.
user = User.first new_user = user.clone user.name # => "Bob" new_user.name = "Joe" user.name # => "Joe" user.object_id == new_user.object_id # => false user.name.object_id == new_user.name.object_id # => true user.name.object_id == user.dup.name.object_id # => false
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# File lib/active_record/core.rb, line 739 def connection_handler self.class.connection_handler end
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# File lib/active_record/core.rb, line 529
Duped objects have no id assigned and are treated as new records. Note that this is a “shallow” copy as it copies the object’s attributes only, not its associations. The extent of a “deep” copy is application specific and is therefore left to the application to implement according to its need. The dup method does not preserve the timestamps (created|updated)_(at|on) and locking column.
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# File lib/active_record/core.rb, line 576 def encode_with(coder) self.class.yaml_encoder.encode(@attributes, coder) coder["new_record"] = new_record? coder["active_record_yaml_version"] = 2 end
Populate coder
with attributes about this record that should be serialized. The structure of coder
defined in this method is guaranteed to match the structure of coder
passed to the init_with
method.
Example:
class Post < ActiveRecord::Base end coder = {} Post.new.encode_with(coder) coder # => {"attributes" => {"id" => nil, ... }}
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# File lib/active_record/core.rb, line 643 def freeze @attributes = @attributes.clone.freeze self end
Clone and freeze the attributes hash such that associations are still accessible, even on destroyed records, but cloned models will not be frozen.
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# File lib/active_record/core.rb, line 649 def frozen? @attributes.frozen? end
Returns true
if the attributes hash has been frozen.
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# File lib/active_record/core.rb, line 763 def full_inspect inspect_with_attributes(all_attributes_for_inspect) end
Returns all attributes of the record as a nicely formatted string, ignoring .attributes_for_inspect
.
Post.first.full_inspect #=> "#<Post id: 1, title: "Hello, World!", published_at: "2023-10-23 14:28:11 +0000">"
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# File lib/active_record/core.rb, line 630 def hash id = self.id if primary_key_values_present? self.class.hash ^ id.hash else super end end
Delegates to id in order to allow two records of the same type and id to work with something like:
[ Person.find(1), Person.find(2), Person.find(3) ] & [ Person.find(1), Person.find(4) ] # => [ Person.find(1) ]
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# File lib/active_record/core.rb, line 487 def init_with(coder, &block) coder = LegacyYamlAdapter.convert(coder) attributes = self.class.yaml_encoder.decode(coder) init_with_attributes(attributes, coder["new_record"], &block) end
Initialize an empty model object from coder
. coder
should be the result of previously encoding an Active Record model, using encode_with
.
class Post < ActiveRecord::Base end old_post = Post.new(title: "hello world") coder = {} old_post.encode_with(coder) post = Post.allocate post.init_with(coder) post.title # => 'hello world'
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# File lib/active_record/core.rb, line 753 def inspect inspect_with_attributes(attributes_for_inspect) end
Returns the attributes of the record as a nicely formatted string.
Post.first.inspect #=> "#<Post id: 1, title: "Hello, World!", published_at: "2023-10-23 14:28:11 +0000">"
The attributes can be limited by setting .attributes_for_inspect
.
Post.attributes_for_inspect = [:id, :title] Post.first.inspect #=> "#<Post id: 1, title: "Hello, World!">"
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# File lib/active_record/core.rb, line 769 def pretty_print(pp) return super if custom_inspect_method_defined? pp.object_address_group(self) do if @attributes attr_names = attributes_for_inspect.select { |name| _has_attribute?(name.to_s) } pp.seplist(attr_names, proc { pp.text "," }) do |attr_name| attr_name = attr_name.to_s pp.breakable " " pp.group(1) do pp.text attr_name pp.text ":" pp.breakable value = attribute_for_inspect(attr_name) pp.text value end end else pp.breakable " " pp.text "not initialized" end end end
Takes a PP and prettily prints this record to it, allowing you to get a nice result from pp record
when pp is required.
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# File lib/active_record/core.rb, line 735 def readonly! @readonly = true end
Marks this record as read only.
customer = Customer.first customer.readonly! customer.save # Raises an ActiveRecord::ReadOnlyRecord
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# File lib/active_record/core.rb, line 671 def readonly? @readonly end
Returns true
if the record is read only.
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# File lib/active_record/core.rb, line 583
Returns a hash of the given methods with their names as keys and returned values as values.
topic = Topic.new(title: "Budget", author_name: "Jason") topic.slice(:title, :author_name) => { "title" => "Budget", "author_name" => "Jason" }
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# File lib/active_record/core.rb, line 709 def strict_loading!(value = true, mode: :all) unless [:all, :n_plus_one_only].include?(mode) raise ArgumentError, "The :mode option must be one of [:all, :n_plus_one_only] but #{mode.inspect} was provided." end @strict_loading_mode = mode @strict_loading = value end
Sets the record to strict_loading mode. This will raise an error if the record tries to lazily load an association.
user = User.first user.strict_loading! # => true user.address.city => ActiveRecord::StrictLoadingViolationError user.comments.to_a => ActiveRecord::StrictLoadingViolationError
Parameters¶ ↑
-
value
- Boolean specifying whether to enable or disable strict loading. -
:mode
- Symbol specifying strict loading mode. Defaults to :all. Using :n_plus_one_only mode will only raise an error if an association that will lead to an n plus one query is lazily loaded.
Examples¶ ↑
user = User.first user.strict_loading!(false) # => false user.address.city # => "Tatooine" user.comments.to_a # => [#<Comment:0x00...] user.strict_loading!(mode: :n_plus_one_only) user.address.city # => "Tatooine" user.comments.to_a # => [#<Comment:0x00...] user.comments.first.ratings.to_a => ActiveRecord::StrictLoadingViolationError
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# File lib/active_record/core.rb, line 676 def strict_loading? @strict_loading end
Returns true
if the record is in strict_loading mode.
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# File lib/active_record/core.rb, line 726 def strict_loading_all? @strict_loading_mode == :all end
Returns true
if the record uses strict_loading with :all
mode enabled.
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# File lib/active_record/core.rb, line 721 def strict_loading_n_plus_one_only? @strict_loading_mode == :n_plus_one_only end
Returns true
if the record uses strict_loading with :n_plus_one_only
mode enabled.
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# File lib/active_record/core.rb, line 598
Returns an array of the values returned by the given methods.
topic = Topic.new(title: "Budget", author_name: "Jason") topic.values_at(:title, :author_name) => ["Budget", "Jason"]
Private Instance Methods
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# File lib/active_record/core.rb, line 859 def all_attributes_for_inspect return [] unless @attributes attribute_names end
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# File lib/active_record/core.rb, line 855 def attributes_for_inspect self.class.attributes_for_inspect == :all ? all_attributes_for_inspect : self.class.attributes_for_inspect end
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# File lib/active_record/core.rb, line 825 def custom_inspect_method_defined? self.class.instance_method(:inspect).owner != ActiveRecord::Base.instance_method(:inspect).owner end
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# File lib/active_record/core.rb, line 805 def init_internals @readonly = false @previously_new_record = false @destroyed = false @marked_for_destruction = false @destroyed_by_association = nil @_start_transaction_state = nil klass = self.class @primary_key = klass.primary_key @strict_loading = klass.strict_loading_by_default @strict_loading_mode = klass.strict_loading_mode klass.define_attribute_methods end
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# File lib/active_record/core.rb, line 822 def initialize_internals_callback end
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# File lib/active_record/core.rb, line 840 def inspect_with_attributes(attributes_to_list) inspection = if @attributes attributes_to_list.filter_map do |name| name = name.to_s if _has_attribute?(name) "#{name}: #{attribute_for_inspect(name)}" end end.join(", ") else "not initialized" end "#<#{self.class} #{inspection}>" end
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# File lib/active_record/core.rb, line 836 def inspection_filter self.class.inspection_filter end
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# File lib/active_record/core.rb, line 801 def to_ary nil end
+Array#flatten+ will call to_ary
(recursively) on each of the elements of the array, and then rescues from the possible NoMethodError
. If those elements are ActiveRecord::Base
‘s, then this triggers the various method_missing
’s that we have, which significantly impacts upon performance.
So we can avoid the method_missing
hit by explicitly defining to_ary
as nil
here.
See also tenderlovemaking.com/2011/06/28/til-its-ok-to-return-nil-from-to_ary.html