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DEFAULT_ENV | = | -> { RAILS_ENV.call || "default_env" } |
RAILS_ENV | = | -> { (Rails.env if defined?(Rails.env)) || ENV["RAILS_ENV"].presence || ENV["RACK_ENV"].presence } |
[W] | connection_specification_name |
Clears the query cache for all connections associated with the current thread.
# File activerecord/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
Returns true
if Active Record is connected.
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.
# File activerecord/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
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
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.
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.
Return the specification name from the current class or its parent.
# File activerecord/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
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 activerecord/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
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
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 activerecord/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