Getting actionlink parameter out of route path

Question

I'm trying to add a webform that allows the user to add a database entry with a specific foreign key.

I'm creating the link like this

<%= Html.ActionLink("Edit", "EditSub", new { id = id }) %>

and the resulting URL is http://localhost:3015/TumourGroup/CreateSub/2 (where 2 is the id I passed to the actionlink earlier). The question is, how do I retrieve the value of id from the URL? I'm using it to grab the "main" table so that I can create a new table entry that has a foreign key pointing to the "main" table.

Answer 1

Have your controller function CreateSub take in int id

public ActionResult CreateSub (int id)

If you want to go to the form with this id, then post with a different set of data, you'd need two functions, differentiated by

[AcceptVerbs(HttpVerbs.Get)]
public ActionResult CreateSub (int id)

The get is for navigating to your entry form, the post is called when the form posts.

[AcceptVerbs(HttpVerbs.Post)]
public ActionResult CreateSub (TumourGroupSubcategory tumourSubgroupToCreate)

BELOW IS RESPONDING TO CLARIFICATION IN COMMENTS:

Well, if you forego the strongly typed view, you can just do

ViewData["id"] = id;
ViewData["subGroupToCreate"] = ...

Alternatively you can do it in the second form on the client side with Javascript or Jquery

Answer 2

Assuming that TumourGroup is the name of a controller, and you have a route that looks something like this:

routes.MapRoute(
    "Default",
    "{controller}, {action}, {id}",
    new { controller="Home", action="Index", id="" }
)

Then in your TumourGroup controller, you just need a controller method that looks like this:

public ActionResult CreateSub (int id)
{
    // blah
}  

The parameter id will contain your id from the Url.

EDIT: To include the id when you are submitting a form:

public ActionResult CreateSub (TumourGroupSubcategory tumourSubgroupToCreate)
{
    // blah
}  

1. Add the id as a property to your TumorGroupSubcategory class.

2. In the form view you are submitting, include a hidden field that is named the same as the id in your TumorGroupSubcategory class, and populate it with your id field.

When your user submits the form, the Model Binder will pick up the field, and put it into the id property of tumourSubgroupToCreate automatically.