Question

tldr> Once a customer has been selected, how can all other controllers execute their actions always in the ‘context’ of that customer without manually passing the ID around?

I’m trying to figure out what the ‘right’ way is to handle the situation where one entire controller (or more) are all dependent on an idea from a previous controller. For instance, let’s say you were building some kind of customer management system. There’d be all kinds of customer functions, probably located on CustomerController. But then when you got into order management, you’d likely want to have an OrderController.

If you had only one OrderController, your methods would probably look like:

public ActionResult Edit(string id){…}

The id would be the id of the order, right? Where I get a little lost is when I need to get back to the customer. It’s like the ‘context’ of all the actions taking place are within the customer. You could do this by always adding the customer id onto actions (URLs):

http://site.com/Orders/Edit/1234?customerId=abc

But this seems like it gets quite tedious to be grabbing that value and jamming it onto every action. There are options like Session, but that seems sloppy.

What’s the right way to do this?

Answer 1

If you really want to avoid storing your value into the session, you can use an action filter that takes care of the value. I’ve used this approach once and it goes like this:

1. Create a new route that contains a placeholder for your value, e.g. customer id.
2. When customer is selected, add the id to route for the next GET or POST call.
3. Create an action filter that reads the id from route and adds it to action parameters before action takes place (OnActionExecuting). When action is done this same filter adds the id from action parameters back to route data (OnActionExecuted).
4. Use this new action filter wherever you wish, probably at controller level.

Now your customer id is easily persisted in the URL even though you do not manually add it to all links. If you need to use the customer id in an action method, you just add a parameter with the correct name. It is persisted over action method call even if you do not take it as a parameter.

If you want to go further, in your new action filter you can get the data from database and add that to action parameters instead of adding only id. This way you can further simplify your action methods.