PLEASE! how to connect to a database dynamically

rubyonrails-talk
1

I have a login dialog. It yields a user name and a password to a controller. From there, what is the best way (if any) to establish a database connection using the dynamically established user name and password?

(We *have to* use the database's built in ACL features)

PLEASE help. This will make or break our decision to use RoR as a framework for a large medical web application

Horst

2

I think you would need to look at this

it allows you to establish a connection in your controllers.

3

you could do this:

ActiveRecord::Base.establish_connection( :database => “blah”, :username => @logged_in_username, :password => @logged_in_password, :adapter => “mysql”,

:database => “whatever”, :host => “localhost” )

you might also look at the wiki: http://wiki.rubyonrails.org/rails/pages/HowtosDatabase under the “Multiple Databases” section

4

If I do this, it will work just the once. I have more than hundred tables. I want to log in for all of them.

If I create an abstract model base class, derived from ActiveRecord::Base and if I have the login parameters available in a *controller*, how do I pass the parameters to that abstract base class so that all subsequent model actions of models derived form that abstract class will sucessfully connect?

It seems so easy, and is straightforward in any other framework I know - but I can't figure out how to do in in RoR

Horst

5

Ah, but if I do ActiveRecord::Base::establish_connection(... in my login_controller instead, it seems to work. Thanks!

Horst

6

1.) we have a common database (on PostgreSQL) that is accessed by multiple programs, the RoR web app only one of many. Access control is enforced via the backend built in ACL mechanisms - we keep it DRY and don't want to re-implement access control in every new application accessing the database. => database access parameters are determined AFTER the user went through the login screen

2.) part of our application extends two proprietary legacy databases (Interbase/Firebird backends to proprietary frontends) which we are not allowed to export and import into our own database

3.) there is another proprietary database (pharmaceutical reference information) to which users can optionally subscribe - again, this one will always reside in a separate backend.

So what I do is: -> display login screen -> depending on login data, connect to the main database, get authentication parameters for third party databases from there, and connect to third party databases as well (if applicable for that user)

This is not a traditional web app. This is replacing a complex GUI desktop application with a browser based application

Horst

7

Hi Horst,

You could try doing this:

# inside login controller @session[:main_login_params] = {:username => @params[:username], :password => @params[:password]} @main_db_params = {:database =>...,...} class YourModel< ActionRecord::Base end YourModel.establish_connection(@main_db_params.merge(@session[:main_login_params])) # YourModel.find etc etc. # you could store the Legacy DB params in the @session too (may need to find an alternative if there are a large number of users. lots of users with complex session variables = more disk space taken up. LegacyModel.establish_connection(@session[...])

Hope this helps.

Regards, Simon