Clear all active sessions for a user in rails - ruby-on-rails

Here, I don’t have a session cookie. I know only the user id of the user I want to clear all active sessions for.
Currently, I am going through each session in the sessions table and checking warden.user.user.key attribute. If it is equal to that user id I am destroying this session.
This works fine but the sessions table contains more than a million records. Is there an optimized way to do so?

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Rails prevent double vote via cookies?

Relatively new rails programmer here, so bear with me.
I have an app where registered users can create polls but anyone can answer the polls.
I am using Devise for my authentication. I want non-authenticated users to be able to answer the polls but I want to prevent double-voting.
I assume this should be done with persistent (not session) cookies, but I'm not sure. So when the user enters the site, I create a user in devise and I store some random value in both the User model and in the cookie, and I check that the user has not answered the question previously when he/she attempts to load my "answer" page?
Can someone give me some advice on whether this is the right approach and/or point me towards a resource to help me get started?
I have found relatively little information out there on how to manage persistent cookies in Rails.
You can't reliably prevent people from voting multiple times without logging in. It's not possible. I guess people could also create multiple user accounts to vote so there is no fool proof way.
Cookies are often cleared automatically by certain popular cleaners and unless you are only going to allow people to vote on a product they have purchased I think you are kind fighting a lost battle.
Stack Overflow limits voting capability by making sure a certain level has been achieved before being allowed to vote but I guess that's not really applicable to your scenario.
This is not so much about sessions and cookies and more about setting up your database to record a vote including the voter id.
In the view that allows users to vote I would suggest that you switch between a voted icon and a vote now link depending on whether or not the currently logged in user has voted.
To determine if the user has voted then include the user id of the currently logged in user in a question_vote xref table.
For the belt and braces approach to prevent abuse of the html in the browser add the check to the validations of the question_vote record.
I would do this by adding a can_vote? method to the user model that accepts a question id as a parameter then you can use the question_id plus the user id to find a matching record in the question_vote table if a reordx is found return false otherwise return true

belongs_to with default fallback

Currently, My Rails (3) app creates objects before their relation is known (I store the Comment, then ask the user to log-in/sign-in to validate that comment, after which the Comment gets a User assigned).
I'd like to make sure each Comment falls back to a user at all times. To avoid having to test everywhere for #comment.user. Ensuring a user also allows me to validate_presence.
I can see two ways, both seem quite ugly. Maybe I am missing some feature of Rails or ActiveRecord.
In the seed or migration, create a user with ID 1, call that anonymous and assign that as fallback.
in comment.rb check for user_id on load, if null, assign a User.new to it.
How is this usually done?
How about adding user records for all comments. Even for not signed-in users. This is just one more record per anonymous comment. And in user records you can keep last IP address and other stuff like max anonymous comments per day.
After user sign-in, reassign comments to the right user and delete temporary user. For new user sign-ups update temporary user records to verified state.
Notice that each anonymous comment has owner, but the user isn't verified. And verification state can be treated as user attribute.
Yes, it is possible to keep unverified users data in session. However sessions sometimes are configured to be stored in a database. So result is the same as storing temporary users in main users table in terms of disk usage, but the data is more fragmented.
Maybe temporarily store necessary stuff in session, not in database? I don't like the idea of storing partially complete records in database. It is a risky play with database integrity. Alternatively, you could create a table with text column which would contain those incomplete objects serialized.

Is there a way to load and set a specific session from the database in ruby on rails?

My Scenario:
Sessions are being stored in the database using ActiveRecord::SessionStore
User is on site at 'http://domain.com '
they go to secure checkout at 'https://domain.secure.com' (our app has lots of domains, but want to send everyone through secure checkout on the same domain to save SSL headaches).
We append session_id and a hash to authenticate and identify the user at 'https://domain.secure.com'
Load that users session data by doing ActiveRecord::SessionStore::Session.find_by_session_id(session_id)
The above all works fine. BUT how can I actually set the same session_id to the user once they are on 'https://domain.secure.com'? I can loop through the data and assign it to the user's session, but Rails automatically gives the user a new session_id on 'https://domain.secure.com'. I want the users session to be stored in the same database row regardless of whether they are on 'http://domain.com' or 'https://domain.secure.com'
Why do I want to do this? For ease of expiring sessions. I can just remove that row from the sessions table.
Otherwise I'm thinking I'll have to add a user_id column to the sessions table and then when i want to expire the session, I delete all rows for that user. But this sounds more complicated to me. I'd rather just have one row in the sessions table.
Any suggestions?
A couple ways to approach this.
One, you could look at a higher level of abstraction for authentication that lets you manage cross server. For example, Devise http://github.com/plataformatec/devise
Second, you can override the whole session controller and write your own session manager. A bit more work, but not that complicated if you ultimately need a bunch of custom functionality. I remember correctly, start with this in your environment:
CGI::Session::ActiveRecordStore.session_class = MySessionClass
and go from there..

How to automatically maintain a table of users that have been authenticated by IIS 7.0 using Windows Authentication

I want to build and maintain a table of users. All users that access the ASP.NET MVC site are authenticated via Windows Authentication so they're bound to have a unique username. I'm grabbing the user name from:
System.Web.HttpContext.Current.User.Identity.Name
I feel like I could go two ways with this.
Anytime the user table or any tables that references the user table are accessed, I could add the user if it doesn't exist. I'm worried this might be very error prone if user's existance isn't checked.
Anytime the user visits any page on the site, check if that user exists in the db and if they don't exist, add the user. This may have a lot of overhead as it'll be checked every page change.
I'd like to hear which of these is the better solution and also how to implement them.
I think a better way would be something similar to the option two.
Anytime a user visits a page, check a session variable to see if that user was checked against the DB. If the session variable is not there, check if that user exists in the DB, add the user to your table if necessary, then set the session variable.
That way you don't have to hit the DB on every request.

Rails w/ ActiveRecord Sessions and Restful-authentication: when does the sessions table get written to?

Warning: some of this may be very wrong-headed, so please let me know if my assumptions are incorrect.
Here's what I'm trying to accomplish:
I'm using restful-authentication for login. However, as I am using flex/ruby_amf for my UI, I have to separately authenticate each connection from flex.
The way I decided to do that was by having the log-in screen redirect to the embedded flash page, inserting the session-id as a flashvar. The flash app sends the session-id with every request, and a before filter on all of the relevant controllers checks to see if the user associated with the session identified by the session-id is logged on.
The way I associate a user with session is by adding a 'user_id' column to the sessions table, and doing an sql "update sessions set user_id...'" type query called from the login function.
However, the user_id only gets updated the 2nd time the user logs in. A little investigating showed that the record in the sessions table does not yet exist during execution of the login function.
So, if everything up to this point makes sense, and conforms to best-practices, etc., then my question is:
At what point in time is the record in the sessions table created? Is there a way to update the session object in the login function and have rails write the user_id to the database for me?
The behavior of sessions in rails is a real mystery to me. I'd appreciate any help.
Thank you.
In Rails 2.3, the session is saved after the Rack application has finished its processing. In traditional Rails applications, this will be after the request is fully processed: before filters, controller action, view rendering, and after filters. Look in actionpack/lib/action_dispatch/vendor/rack-1.1.pre/rack/session/abstract/id.rb.
If you think about it, this makes perfect sense. Writing the session to its store every time you place something in the session would incur a lot of extra overhead.
It's Rails, so if you want to mess with it enough, sure, you can monkeypatch yourself a way to write the session to store anytime you wish. I don't recommend it. You'll end up having to rework the code constantly as Rails evolves.
You are right that for ActiveRecord::SessionStore, one row does map to one session. The data column is an encoded form of every object you put in the session. Each time a request comes in, Rails has to reconstitute the session as it existed by creating new instances of all the objects you previously stored in it.

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