instance method
establish_connection
Ruby on Rails 5.2.8.1
Since v4.0.13Signature
establish_connection(config = nil)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.
Parameters
-
configopt = nil
Source
# File activerecord/lib/active_record/connection_handling.rb, line 49
def establish_connection(config = nil)
raise "Anonymous class is not allowed." unless name
config ||= DEFAULT_ENV.call.to_sym
spec_name = self == Base ? "primary" : name
self.connection_specification_name = spec_name
resolver = ConnectionAdapters::ConnectionSpecification::Resolver.new(Base.configurations)
spec = resolver.resolve(config).symbolize_keys
spec[:name] = spec_name
connection_handler.establish_connection(spec)
end
Defined in activerecord/lib/active_record/connection_handling.rb line 49
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Defined in ActiveRecord::ConnectionHandling