根据值通过Html.ActionLink传递参数

Question

In my website with paging and search options i have to redirect the user and pass the search options. With this action I don't want to pass the search model with the URL (ex. http://localhost:1234/?Project.Models.TestModel=... .).

My actionlink right now is as follows:

@Html.ActionLink(i.ToString(), "Index", new { idtrips = Model.idTrips, inituser = Model.initUser, date = Model.date.ToString("ddMMyyyy"), page = i})

When clicked this results in a following header: http://localhost:58763/?idtrips=0&inituser=0&date=05042016&page=5

My question is: Can you somehow add if clauses to the Html.ActionLink to only give values if they are needed. For example I only have a date set, then I want the Url to be: http://localhost:58763/?date=05042016&page=5 . The other values have a default value in my controller so this url will work but i'm not able to generate it.

My controller:

public ActionResult Index(long idtrips = 0, long inituser = 0, string date = "", int page = 1)
    { ... }

What i'm looking for is something like this,:

@Html.ActionLink(i.ToString(), "Index", new { if(Model.idTrips > 0) { idtrips = Model.idTrips,} page = i})

Answer 1

You could probably accomplish this with a ternary statement (eg an inline-if statement) :

new { idtrips = Model.idTrips > 0 ? Model.IdTrips : 0, page = i}

Since you have a default parameter value for idtrips , this should only set it to something else if it is greater than 0.

If you don't want the value to appear at all, you could consider simply making it a nullable long long? parameter (and ensure this matches on your Model as well):

public ActionResult Index(long? idtrips = 0, ... ) { ... }

Using this approach, you could simply set it as expected :

new { idtrips = Model.idTrips, page = i}

And if Model.idTrips was null (eg the default value), then it would point to :

Controller/Index?page=1

However, if it was any non-null value, it would render the querystring parameter as expected :

Controller/Index?idtrips=42&page=1