Should controller methods take arguments?

Question

Given that there is file selection widget on the view and controller need to handle event of selecting file, should I rather write controller method:

public void fileSelected(String filePath){
  //process filePath
}

or

public void fileSelected(){
  String filePath = view.getSelectedFilePath();
  //process filePath
}

The first approach seems to introduce less coupling between C and V: C don't know what exactly data does C need while handling given event.

But it requires creating a lot of verbose methods similar to getSelectedFile on V side.

On the other hand, second approach may lead to cluttered controller methods in more complex cases than in example (much more data to pass than just filePath).

From your own experience, which approach do you prefer?

Answer 1

The first approach is my favourite. The only difference is I would rather use an object (like Mario suggested) to pass arguments to the method. This way method's signature will not change when you add or remove some of the arguments. Less coupling is always good :)

One more thing: If You want to try the second solution I recommend using a ViewFactory to remove view logic from the controller.

Answer 2

The first approach is the way to go;

public void fileSelected(String filePath){
  //process filePath
}

The Controller should not care about how the View looks like or how it's implemented. It gets much clearer for the developer as well, when creating/updating the view, to know what an action in the controller wants. Also it makes it easier for method overloading.

Though, I don't know really how String filePath = view.getSelectedFilePath(); would work. Are we talking about parsing the View code/markup?

On the other hand, second approach may lead to cluttered controller methods in more complex cases than in example (much more data to pass than just filePath).

That's when you would create a View Model class (let's say we name it MyViewModel) to store all the properties that you need to send (may it be 10 properties) and then pass that in the action: fileSelected(MyViewModel model). That's how it's intended to be used and what the *ModelBinder's in asp.net mvc are there to help you with.