Module: ActiveRecord::ConnectionHandling
- Included in:
- Base
- Defined in:
- lib/active_record/connection_adapters/mysql2_adapter.rb,
lib/active_record/connection_handling.rb,
lib/active_record/connection_adapters/sqlite3_adapter.rb,
lib/active_record/connection_adapters/postgresql_adapter.rb
Overview
:nodoc:
Constant Summary collapse
- RAILS_ENV =
-> { (Rails.env if defined?(Rails.env)) || ENV["RAILS_ENV"].presence || ENV["RACK_ENV"].presence }
- DEFAULT_ENV =
-> { RAILS_ENV.call || "default_env" }
- ER_BAD_DB_ERROR =
1049
Instance Attribute Summary collapse
-
#connection_specification_name ⇒ Object
Return the specification name from the current class or its parent.
Instance Method Summary collapse
-
#clear_cache! ⇒ Object
:nodoc:.
-
#clear_query_caches_for_current_thread ⇒ Object
Clears the query cache for all connections associated with the current thread.
-
#connected? ⇒ Boolean
Returns
true
if Active Record is connected. -
#connected_to(database: nil, role: nil, prevent_writes: false, &blk) ⇒ Object
Connects to a database or role (ex writing, reading, or another custom role) for the duration of the block.
-
#connected_to?(role:) ⇒ Boolean
Returns true if role is the current connected role.
-
#connection ⇒ Object
Returns the connection currently associated with the class.
-
#connection_config ⇒ Object
Returns the configuration of the associated connection as a hash:.
- #connection_pool ⇒ Object
-
#connects_to(database: {}) ⇒ Object
Connects a model to the databases specified.
-
#current_role ⇒ Object
Returns the symbol representing the current connected role.
-
#establish_connection(config_or_env = nil) ⇒ Object
Establishes the connection to the database.
-
#lookup_connection_handler(handler_key) ⇒ Object
:nodoc:.
-
#mysql2_connection(config) ⇒ Object
Establishes a connection to the database that’s used by all Active Record objects.
-
#postgresql_connection(config) ⇒ Object
Establishes a connection to the database that’s used by all Active Record objects.
-
#primary_class? ⇒ Boolean
:nodoc:.
- #remove_connection(name = nil) ⇒ Object
-
#resolve_config_for_connection(config_or_env) ⇒ Object
:nodoc:.
- #retrieve_connection ⇒ Object
- #sqlite3_connection(config) ⇒ Object
-
#with_handler(handler_key, &blk) ⇒ Object
:nodoc:.
Instance Attribute Details
#connection_specification_name ⇒ Object
Return the specification name from the current class or its parent.
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# File 'lib/active_record/connection_handling.rb', line 212 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 |
Instance Method Details
#clear_cache! ⇒ Object
:nodoc:
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# File 'lib/active_record/connection_handling.rb', line 258 def clear_cache! # :nodoc: connection.schema_cache.clear! end |
#clear_query_caches_for_current_thread ⇒ Object
Clears the query cache for all connections associated with the current thread.
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# File 'lib/active_record/connection_handling.rb', line 194 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 |
#connected? ⇒ Boolean
Returns true
if Active Record is connected.
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# File 'lib/active_record/connection_handling.rb', line 242 def connected? connection_handler.connected?(connection_specification_name) end |
#connected_to(database: nil, role: nil, prevent_writes: false, &blk) ⇒ Object
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
For cases where you may want to connect to a database outside of the model, you can use connected_to
with a database
argument. The database
argument expects a symbol that corresponds to the database key in your config.
ActiveRecord::Base.connected_to(database: :animals_slow_replica) do
Dog.run_a_long_query # runs a long query while connected to the +animals_slow_replica+
end
This will connect to a new database for the queries inside the block. By default the ‘:writing` role will be used since all connections must be assigned a role. If you would like to use a different role you can pass a hash to database:
ActiveRecord::Base.connected_to(database: { readonly_slow: :animals_slow_replica }) do
# runs a long query while connected to the +animals_slow_replica+ using the readonly_slow role.
Dog.run_a_long_query
end
When using the database key a new connection will be established every time. It is not recommended to use this outside of one-off scripts.
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# File 'lib/active_record/connection_handling.rb', line 118 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 if role == writing_role with_handler(role.to_sym) do connection_handler.while_preventing_writes(prevent_writes, &blk) end else with_handler(role.to_sym, &blk) end else raise ArgumentError, "must provide a `database` or a `role`." end end |
#connected_to?(role:) ⇒ Boolean
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
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# File 'lib/active_record/connection_handling.rb', line 152 def connected_to?(role:) current_role == role.to_sym end |
#connection ⇒ Object
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.
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# File 'lib/active_record/connection_handling.rb', line 205 def connection retrieve_connection end |
#connection_config ⇒ Object
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.
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# File 'lib/active_record/connection_handling.rb', line 229 def connection_config connection_pool.spec.config end |
#connection_pool ⇒ Object
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# File 'lib/active_record/connection_handling.rb', line 233 def connection_pool connection_handler.retrieve_connection_pool(connection_specification_name) || raise(ConnectionNotEstablished) end |
#connects_to(database: {}) ⇒ Object
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.
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# File 'lib/active_record/connection_handling.rb', line 68 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 |
#current_role ⇒ Object
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/connection_handling.rb', line 165 def current_role connection_handlers.key(connection_handler) end |
#establish_connection(config_or_env = nil) ⇒ Object
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.
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# File 'lib/active_record/connection_handling.rb', line 49 def establish_connection(config_or_env = nil) config_hash = resolve_config_for_connection(config_or_env) connection_handler.establish_connection(config_hash) end |
#lookup_connection_handler(handler_key) ⇒ Object
:nodoc:
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# File 'lib/active_record/connection_handling.rb', line 169 def lookup_connection_handler(handler_key) # :nodoc: handler_key ||= ActiveRecord::Base.writing_role connection_handlers[handler_key] ||= ActiveRecord::ConnectionAdapters::ConnectionHandler.new end |
#mysql2_connection(config) ⇒ Object
Establishes a connection to the database that’s used by all Active Record objects.
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# File 'lib/active_record/connection_adapters/mysql2_adapter.rb', line 14 def mysql2_connection(config) config = config.symbolize_keys config[:flags] ||= 0 if config[:flags].kind_of? Array config[:flags].push "FOUND_ROWS" else config[:flags] |= Mysql2::Client::FOUND_ROWS end client = Mysql2::Client.new(config) ConnectionAdapters::Mysql2Adapter.new(client, logger, nil, config) rescue Mysql2::Error => error if error.error_number == ER_BAD_DB_ERROR raise ActiveRecord::NoDatabaseError else raise end end |
#postgresql_connection(config) ⇒ Object
Establishes a connection to the database that’s used by all Active Record objects
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# File 'lib/active_record/connection_adapters/postgresql_adapter.rb', line 33 def postgresql_connection(config) conn_params = config.symbolize_keys conn_params.delete_if { |_, v| v.nil? } # Map ActiveRecords param names to PGs. conn_params[:user] = conn_params.delete(:username) if conn_params[:username] conn_params[:dbname] = conn_params.delete(:database) if conn_params[:database] # Forward only valid config params to PG::Connection.connect. valid_conn_param_keys = PG::Connection.conndefaults_hash.keys + [:requiressl] conn_params.slice!(*valid_conn_param_keys) conn = PG.connect(conn_params) ConnectionAdapters::PostgreSQLAdapter.new(conn, logger, conn_params, config) rescue ::PG::Error => error if error..include?(conn_params[:dbname]) raise ActiveRecord::NoDatabaseError else raise end end |
#primary_class? ⇒ Boolean
:nodoc:
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# File 'lib/active_record/connection_handling.rb', line 219 def primary_class? # :nodoc: self == Base || defined?(ApplicationRecord) && self == ApplicationRecord end |
#remove_connection(name = nil) ⇒ Object
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# File 'lib/active_record/connection_handling.rb', line 246 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 |
#resolve_config_for_connection(config_or_env) ⇒ Object
:nodoc:
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# File 'lib/active_record/connection_handling.rb', line 179 def resolve_config_for_connection(config_or_env) # :nodoc: raise "Anonymous class is not allowed." unless name config_or_env ||= DEFAULT_ENV.call.to_sym pool_name = primary_class? ? "primary" : name self.connection_specification_name = pool_name resolver = ConnectionAdapters::ConnectionSpecification::Resolver.new(Base.configurations) config_hash = resolver.resolve(config_or_env, pool_name).symbolize_keys config_hash[:name] = pool_name config_hash end |
#retrieve_connection ⇒ Object
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# File 'lib/active_record/connection_handling.rb', line 237 def retrieve_connection connection_handler.retrieve_connection(connection_specification_name) end |
#sqlite3_connection(config) ⇒ Object
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# File 'lib/active_record/connection_adapters/sqlite3_adapter.rb', line 18 def sqlite3_connection(config) config = config.symbolize_keys # Require database. unless config[:database] raise ArgumentError, "No database file specified. Missing argument: database" end # Allow database path relative to Rails.root, but only if the database # path is not the special path that tells sqlite to build a database only # in memory. if ":memory:" != config[:database] config[:database] = File.(config[:database], Rails.root) if defined?(Rails.root) dirname = File.dirname(config[:database]) Dir.mkdir(dirname) unless File.directory?(dirname) end db = SQLite3::Database.new( config[:database].to_s, config.merge(results_as_hash: true) ) ConnectionAdapters::SQLite3Adapter.new(db, logger, nil, config) rescue Errno::ENOENT => error if error..include?("No such file or directory") raise ActiveRecord::NoDatabaseError else raise end end |
#with_handler(handler_key, &blk) ⇒ Object
:nodoc:
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# File 'lib/active_record/connection_handling.rb', line 174 def with_handler(handler_key, &blk) # :nodoc: handler = lookup_connection_handler(handler_key) swap_connection_handler(handler, &blk) end |