instance method
establish_connection
Ruby on Rails 4.2.9
Since v4.0.13Signature
establish_connection(spec = 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: "mysql",
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
-
specopt = nil
Source
# File activerecord/lib/active_record/connection_handling.rb, line 47
def establish_connection(spec = nil)
spec ||= DEFAULT_ENV.call.to_sym
resolver = ConnectionAdapters::ConnectionSpecification::Resolver.new configurations
spec = resolver.spec(spec)
unless respond_to?(spec.adapter_method)
raise AdapterNotFound, "database configuration specifies nonexistent #{spec.config[:adapter]} adapter"
end
remove_connection
connection_handler.establish_connection self, spec
end
Defined in activerecord/lib/active_record/connection_handling.rb line 47
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Defined in ActiveRecord::ConnectionHandling