Zend Framework application design - should session variables be accessed in the Model layer

I am working on this app that accesses session variables开发者_StackOverflow in the model layer. This just seems wrong but am willing to be proven wrong. Maybe not wrong but, in most places in app, session variables are handled in controller and passed in as arguments but, in other places, the session value is just accessed. Am I wrong that this seems like bad practice?

edit: one reason I don't like sessions in models is that it seems to make it more complex to test. Keep it as just params passsed to functions and then recordset passed back.

thx

It depends.

The way I think about this is such:

1. A Model represents your data layer.
2. most of the time that data layer will be DB Table based
3. The Session is just another data storage medium.
4. Conclusion: If the data that your model represents is stored in the Session, than it is OK to access that data from within the model

An example is a Session based shopping cart. My cart's objects are models of my session data.

Controller shd do a check weather session exist or not before using the model which uses that session inside it .

No it shouldn't. The storage type, should be apart from your business logic. For example:

I have one simple plug-in that perform the access check and put the user object on the registry. So, instead of access session, the model have access to the registry, which is well defined.

$User = Zend_Registry::get('User'); // User model object

From the theoretical point of view, everything should be accessed through data mappers. In the future, if you change from session storage to something else, you'll need to update it just in one place. Your models do not need to know from where the data came from.

If you are taking more than one path to get your data, probably this will cause some problems when your application get large.

The OOP and layered systems approach suggestion is to created specialized objects and layers and keep things simple preventing specific actions to be spread all over the code.

But again, you do not need to change that unless you see advantages. Keep in mind that sometimes refactoring is more efficient than try to predict everything.

What's stored in the session variables? If it's simply 'logged in? Y/N', then they probably don't need to be part of the model layer. If, however, it's more complex than that, they are probably inextricably linked to your business model and should be treated as such.

The examples at the bottom of the Zend Test documentation show how to test the full MVC using a login function. Presumably you could do the same when testing models?