Question

How do you map this url
/Topic/topicName/action?topicId=someInt

Where Topic is the controller name (this is const – it always reads “Topic”),
topicName is being ignored
action is action name,
and someInt is the topicId argument for “action”.

Here are couple of examples:
/Topic/c-sharp/AddQuestion?topicId=1

To invoke:
Controller: Topic
Action: AddQuestion
topicId =1

Where this is the action’s singnature in TopicConroller

public ActionResult AddQuestion(int topicId)  

Another example:
/Topic/MySql-queries/AddSubTopic?topicId=1

To invoke:
Controller: Topic
Action: AddSubTopic
topicId =1

Where this is the action’s singnature in TopicConroller

public ActionResult AddSubTopic(int topicId)   

etc. (all actions in Topic controller receive only one argument – that is the topic’s id).

Answer 1

routes.MapRoute(
    "Topics",
    "Topic/{topicName}/{action}",
    new { controller = "Topic", action = "Index" }
);

where you would have:

public class TopicController: Controller
{
    public ActionResult AddQuestion(int topicId) 
    {
        ...
    }
}

and if you cared about the topic name you could have your controller action take it as action parameter:

public ActionResult AddQuestion(int topicId, string topicName) 
{
    ...
}