ASP.NET MVC 4 MvcMovie Tutorial Filter query by multiple search criteria - database

Question

I was going through the MvcMovie Tutorial and I was trying to modify the SearchIndex() call in the MoviesController to search by multiple criteria. The tutorial shows you how to search by title and genre using the following code:
var movies = from m in db.Movies
select m;
if (!String.IsNullOrEmpty(searchString))
{
movies = movies.Where(s => s.Title.Contains(searchString));
}
if (string.IsNullOrEmpty(movieGenre))
return View(movies);
else
{
return View(movies.Where(x => x.Genre == movieGenre));
}
So if I read this right they return all movies then filter on Genre. That would be fine for a dual case but when you add in a 3rd or 4th search criteria you would then increase the amount of if statement calls by a factor of 2 (to the n) - 1 cases. This would get very unruly if for say you had 10 or so columns to search by.
I tried to use something a little more straight forward like:
var movieQry = from m in db.Movies
where ((m.Title !=null && m.Title == searchString) ||
(m.Rating != null && m.Rating == movieRating) ||
(m.Genre != null && m.Genre == movieGenre))
select m;
but that would not return anything when you first visit the page and only works for a single filter (if I select the Genre - I get good results but not when I select Genre and Rating) and I get nothing returned when I enter a search term for Title.
Is there an easier way to accomplish? (At some point I will need to be able to search on dozens of filters for a project I will be writing... and I have other questions about how to search database for entries but for not this will get me moving in the right direction).

Answer 1

if you want to include the column in the criteria if it is not null then try following:
string Title = Request.QueryString["Title"];
string Rating= Request.QueryString["Rating"];
string Genre = Request.QueryString["Genre"];
var movieQry = from m in db.Movies
where ((string.IsNullOrEmpty(Title) ? true : m.Title == Title ) &&
(string.IsNullOrEmpty(Rating) ? true : m.Rating == Rating ) &&
(string.IsNullOrEmpty(Genre) ? true : m.Genre == Genre ))
select m;

Answer 2

Behnam was kind of on the right track. I modified the code as follows:
var movieQry2 = from m in db.Movies
where ((string.IsNullOrEmpty(searchString) ? true : m.Title.Contains(searchString)) &&
(string.IsNullOrEmpty(movieRating) ? true : m.Rating == movieRating) &&
(string.IsNullOrEmpty(movieGenre) ? true : m.Genre == movieGenre))
select m;
This works and gives good results. Sorry Behnam can't give you an accepted answer but I did tick it up as being useful. Thanks for pointing me in the right direction.

Answer 3

Try this:
var movieQry = db.Movies
.Where(x=> (Title == null || x.Title ==Title)
&& (Rating == null || x.Rating == Rating)
&& (Genre == null || x.Genre == Genre))
.ToList();
For other paging and sorting see MVC multiple field search