module ActiveRecord::ConnectionHandling
Constants
- DEFAULT_ENV
- RAILS_ENV
Attributes
Public Instance Methods
Clears the query cache for all connections associated with the current thread.
# File lib/active_record/connection_handling.rb, line 176 def clear_query_caches_for_current_thread ActiveRecord::Base.connection_handlers.each_value do |handler| handler.connection_pool_list.each do |pool| pool.connection.clear_query_cache if pool.active_connection? end end end
Returns true
if Active Record is connected.
# File lib/active_record/connection_handling.rb, line 224 def connected? connection_handler.connected?(connection_specification_name) end
Connects to a database or role (ex writing, reading, or another custom role) for the duration of the block.
If a role is passed, Active Record will look up the connection based on the requested role:
ActiveRecord::Base.connected_to(role: :writing) do Dog.create! # creates dog using dog writing connection end ActiveRecord::Base.connected_to(role: :reading) do Dog.create! # throws exception because we're on a replica end ActiveRecord::Base.connected_to(role: :unknown_role) do # raises exception due to non-existent role end
The `database` kwarg is deprecated in 6.1 and will be removed in 6.2
It is not recommended for use as it re-establishes a connection every time it is called.
# File lib/active_record/connection_handling.rb, line 102 def connected_to(database: nil, role: nil, prevent_writes: false, &blk) if database && role raise ArgumentError, "connected_to can only accept a `database` or a `role` argument, but not both arguments." elsif database if database.is_a?(Hash) role, database = database.first role = role.to_sym end config_hash = resolve_config_for_connection(database) handler = lookup_connection_handler(role) handler.establish_connection(config_hash) with_handler(role, &blk) elsif role prevent_writes = true if role == reading_role with_handler(role.to_sym) do connection_handler.while_preventing_writes(prevent_writes, &blk) end else raise ArgumentError, "must provide a `database` or a `role`." end end
Returns true if role is the current connected role.
ActiveRecord::Base.connected_to(role: :writing) do ActiveRecord::Base.connected_to?(role: :writing) #=> true ActiveRecord::Base.connected_to?(role: :reading) #=> false end
# File lib/active_record/connection_handling.rb, line 134 def connected_to?(role:) current_role == role.to_sym end
Returns the connection currently associated with the class. This can also be used to “borrow” the connection to do database work unrelated to any of the specific Active Records.
# File lib/active_record/connection_handling.rb, line 187 def connection retrieve_connection end
Returns the configuration of the associated connection as a hash:
ActiveRecord::Base.connection_config # => {pool: 5, timeout: 5000, database: "db/development.sqlite3", adapter: "sqlite3"}
Please use only for reading.
# File lib/active_record/connection_handling.rb, line 211 def connection_config connection_pool.spec.config end
# File lib/active_record/connection_handling.rb, line 215 def connection_pool connection_handler.retrieve_connection_pool(connection_specification_name) || raise(ConnectionNotEstablished) end
Return the specification name from the current class or its parent.
# File lib/active_record/connection_handling.rb, line 194 def connection_specification_name if !defined?(@connection_specification_name) || @connection_specification_name.nil? return self == Base ? "primary" : superclass.connection_specification_name end @connection_specification_name end
Connects a model to the databases specified. The database
keyword takes a hash consisting of a role
and a
database_key
.
This will create a connection handler for switching between connections,
look up the config hash using the database_key
and finally
establishes a connection to that config.
class AnimalsModel < ApplicationRecord self.abstract_class = true connects_to database: { writing: :primary, reading: :primary_replica } end
Returns an array of established connections.
# File lib/active_record/connection_handling.rb, line 67 def connects_to(database: {}) connections = [] database.each do |role, database_key| config_hash = resolve_config_for_connection(database_key) handler = lookup_connection_handler(role.to_sym) connections << handler.establish_connection(config_hash) end connections 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
# File lib/active_record/connection_handling.rb, line 147 def current_role connection_handlers.key(connection_handler) end
Establishes the connection to the database. Accepts a hash as input where
the :adapter
key must be specified with the name of a database
adapter (in lower-case) example for regular databases (MySQL, PostgreSQL,
etc):
ActiveRecord::Base.establish_connection( adapter: "mysql2", host: "localhost", username: "myuser", password: "mypass", database: "somedatabase" )
Example for SQLite database:
ActiveRecord::Base.establish_connection( adapter: "sqlite3", database: "path/to/dbfile" )
Also accepts keys as strings (for parsing from YAML for example):
ActiveRecord::Base.establish_connection( "adapter" => "sqlite3", "database" => "path/to/dbfile" )
Or a URL:
ActiveRecord::Base.establish_connection( "postgres://myuser:mypass@localhost/somedatabase" )
In case ActiveRecord::Base.configurations is set (Rails automatically loads the contents of config/database.yml into it), a symbol can also be given as argument, representing a key in the configuration hash:
ActiveRecord::Base.establish_connection(:production)
The exceptions AdapterNotSpecified,
AdapterNotFound and
ArgumentError
may be returned on an error.
# File lib/active_record/connection_handling.rb, line 48 def establish_connection(config_or_env = nil) config_hash = resolve_config_for_connection(config_or_env) connection_handler.establish_connection(config_hash) end
# File lib/active_record/connection_handling.rb, line 228 def remove_connection(name = nil) name ||= @connection_specification_name if defined?(@connection_specification_name) # if removing a connection that has a pool, we reset the # connection_specification_name so it will use the parent # pool. if connection_handler.retrieve_connection_pool(name) self.connection_specification_name = nil end connection_handler.remove_connection(name) end
# File lib/active_record/connection_handling.rb, line 219 def retrieve_connection connection_handler.retrieve_connection(connection_specification_name) end