Since HTTP is a "stateless" protocol, you would potentially need someone to enter their login information everytime they wanted to look at a new page or even refresh the existing one. This is where sessions comes in. In Rails, each session is assigned a unique session id a 32 character string of random hex numbers when it's created and a cookie containing this id is then sent to the client's browser.
From that point on, every request from the browser sends the session id back to the server thus maintaining continuity. Normal guidelines to follow are you should only keep track of the bare minimum in a session such as info to determine the current user like a primary key etc.
Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. How session works in Rails Ask Question. Asked 5 years, 1 month ago. Active 5 years, 1 month ago.
Viewed 3k times. Improve this question. Aetherus After returning the new hash, Is it maintains any data about logged in user in server side? I just gave an answer. Add a comment. Active Oldest Votes. Let's take a look at 2 typical session stores. Encrypted cookie store This is the default session store of Rails applications. Redis session store This session store is not shipped with Rails. It's a separate gem.
Improve this answer. It is a place to store data from first request that can be read from later requests. All the storage mechanisms use cookie to store a unique ID for each session. Generally this ID look up the session data on the server like database table. There is one exception, that is the default and recommended session store is the CookieStore which stores all session data in the cookie itself. It is very light-weighted and it requires zero setup in a new application in order to use session.
The cookie data is encrypted and cryptographically signed to make it tamper-proof. Complex objects should not be stored in the session, as server may not reassemble them between requests which will ultimately results in error. The session can be accessed through the session instance method. If sessions will not be accessed in action's code, they will not be loaded. They are usually 32 bit character long string. We will create a simple log in form using session. Once a user is signed in, his credentials will be saved.
Only signed in users will be able to log in. You can also view all the sign in users. This is a nice way to enhance the user experience on your page. Let's say that you want to show some users a new fancy sign up form and the rest the old form. If you store the version of the sign up form in a session variable, you don't need to persist this info in your database. That can be pretty handy in many ways, if you think about changing the content of a website based on the session's information.
Handling a lot of session data can be pretty confusing, since the session is just a simple storage. That basically means that you have to organize your way of working with sessions. I once had the idea to put all this information into an object.
The flash is there to save the day! So clean, so convenient. In this case, the typical create action would just render the new action using the existing instance variables. Just like the regular flash, this one self destructs automatically after opening. You still have to write view code to display the flash messages. You might also add a class to the message which will allow you to write some custom CSS, for instance turning :success messages green and :error messages red.
Before we talk about authentication, we need to cover controller filters. The idea of these filters is to run some code in your controller at very specific times, for instance before any other code has been run. If it returns false or nil , the request will not succeed. You can specify to only apply the filter for specific actions by specifying the only option, e. The opposite applies by using the :except option… it will run for all actions except those specified.
The whole point of authentication is to make sure that the user is who they say they are. The standard way of managing this is through logging in your user via a sign in form. Once the user is logged in, you keep track of that user using the session until the user logs out. A related concept is authorization. The typical example is the difference between a regular user and an admin user. They both authenticate with the system but only the admin is authorized to make changes to certain things.
You authorize the user to do certain things like delete stuff based on which methods are protected by controller filters that require signin or elevated permissions e. One of these is Devise which we will explore later. But a few principles are useful to know.
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