Question

Hi i’m looking for some help in how to append rows to an existing LINQ object. In the controller method below I have two result sets, i’m looping the Sites and want to add a record to the ‘results’ object for each record in the Sites object.

I’ve tried concat etc but not getting anywhere, just need s small example to assist, many thanks in advance, J

public IQueryable<UsersToSite> FindAllUsersToSites(int userId,SystemType obj)
{

    var results = (from usersToSite in this._db.UsersToSites
           where usersToSite.UserId == userId &&
           usersToSite.SystemTypeId == obj
           orderby usersToSite.Site.SiteDescription
           select usersToSite);

    // Now for each remaining Site append a record thats not physically in the database. From the view the user will be able to click these records to ADD new
    // I'll then build in a search
    var sites = (from site in this._db.Sites
                 where !(from o in _db.UsersToSites where (o.UserId == userId && o.SystemTypeId == obj) select o.SiteId).Contains(site.SiteId)
           orderby site.SiteDescription
           select site);

    foreach (var site in sites)
    {

        // HERE I want to create the new ROW in results object
        //results = new[results] { new { UsersToSiteId = null, AccessTypeId = null } }.Concat(sites);

            //SiteId=site.SiteId,
            //UsersToSiteId = 0,
            //AccessTypeId = 0,
            //UserId = userId


    }

    return results;
}

Answer 1

I don’t think you can, if you want to have keep queryable.
However, if you materialize the results with ToList(), then you can:

var sites = (from site in this._db.Sites
                where !(from o in _db.UsersToSites where (o.UserId == userId && o.SystemTypeId == obj) select o.SiteId).Contains(site.SiteId)
                orderby site.SiteDescription
                select site)
                .ToList();
sites.Add(new Site { UsersToSiteId = null, etc });

If it was LINQ to Objects, you could do Concat.
The problem here that it can’t do ConcatLINQ query that will have one part from SQL and another from objects. You need to materialize results first and then concat to object.