CODEWITHSUNDEEP
c#entity-frameworklinq
Alexander Olson
Alexander Olson

Reputation: 35

Using a Linq query to select objects where any value of a property matches values from a list

So I am trying to filter the modules object list by userID of the currently logged in user. After that I am trying to take the moduleID of those selected object.

Using that I want to filter the reports list to only those that contain a moduleID that matches any of the the previously obtained list of moduleID.

I'm not that particularly knowledgeable on Linq and this is what I came up with:

    var name = User.Identity.GetUserName();
        //gets the currently logged in user:
        ApplicationUser currentUser = 
            (ApplicationUser)db.Users.Single(x => x.UserName == name); 
        //gets moduleID's for modules owned by current user:
        var modules = (from i in db.Modules
                       where i.User == currentUser
                       select i.ModuleID); 
        var Reports = from u in db.Reports
                      where u.moduleID == modules
                      select u;

I'm having problems with the last portion trying to incorporate the contains method into the statement.

Any help would be appreciated.

Upvotes: 1

Views: 2315

Answers (5)

LeBaptiste
LeBaptiste

Reputation: 1186

Use the navigation properties if you have a one to many relation you could do directly in your Where clause:

var name = User.Identity.GetUserName();
var Reports = db.Reports.Where(x => x.Module.User.Name == name);

Upvotes: 0

Raker65
Raker65

Reputation: 11

You're close. In Linq its a little backwards from standard SQL. In its case you want to see if the report's module id is contained in the list of modules, so it would look like this:

  var Reports = from u in db.Reports
                where modules.Contains(u.moduleID)
                select u;

Upvotes: 0

Tahbaza
Tahbaza

Reputation: 9548

You could simplify the multiple queries to one if I'm inferring your table structure correctly:

var name = User.Identity.GetUserName();
var reports = from r in db.Reports
              join m in db.Modules on r.moduleID equals m.ModuleID
              where m.User.UserName == name
              select r;

Upvotes: 1

Dave Greilach
Dave Greilach

Reputation: 895

You're on the right track.

var Reports = from u in db.Reports
              where modules.Contains(u.moduleID)
              select u;

Or using lambda:

var reports = db.Reports.Where(u => modules.Contains(u));

Upvotes: 0

Xiaoy312
Xiaoy312

Reputation: 14477

You can't compare a int to a IEnumerable<int>. However you can check if the moduleID is found within the modules like this :

where modules.Contains(u.moduleID)

Upvotes: 0

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