C# Lambda expression select new

Question

I have this lambda expression:

this.SitesStore.DataSource = 
dc.Sites.Where(s => multipleSites.Select(ms => ms.Siteid )
.Contains(s.Siteid) && s.Cid == int.Parse(Session["Cid"].ToString())).ToList();

But I want to modify it with this Select new instead of Select(ms => ms.Siteid):

Select new { s.Cid, s.Siteid, FullName = dc.fn_GetSiteid(int.Parse(Session["Cid"].ToString()), s.Siteid) + " - " + s.FullName, s.Title, s.Address, s.Phone }

if I just add this Select new I get this error:

'System.Linq.IQueryable' does not contain a definition for 'Contains' and the best extension method overload 'Ext.Net.Utilities.StringUtils.Contains(string, params string[])' has some invalid arguments

multipleSites:

var multipleSites = (from cs in dc.CUsersSites
                        join c in dc.CUsers on cs.UserId equals c.UserId
                        where cs.Cid == int.Parse(Session["Cid"].ToString()) && c.UserName == HttpContext.Current.User.Identity.Name
                        select cs).ToList();

Schemas

CUsersSites (id, UserId, Cid, Siteid)
CUsers (id, UserId, UserName)
Sites (id, Cid, Siteid, FullName)

Possible duplicate of Creating a list of objects from LINQ select new — Kristof U.
– Kristof U., Commented Mar 1, 2018 at 11:17
Please show the exact code that didn't work. You can't just replace a method call with Select new { ... } but you can use Select(ms => new { ... }) — Jon Skeet
– Jon Skeet, Commented Mar 1, 2018 at 11:17
What you want ot acheive with that select? The Contains method should be used on and array, but your new Select(s => new { ... }) returns an anonymous type objects array. — Markiian Benovskyi
– Markiian Benovskyi, Commented Mar 1, 2018 at 11:36
See the edit to my answer, does that work? Making some assumptions here... — blins
– blins, Commented Mar 1, 2018 at 14:29

blins · Accepted Answer · 2018-03-01 15:13:25Z

3

You should just need to add the Select with the correct syntax as @JonSkeet already mentioned. Furthermore, you can simplify and avoid the issue you are getting (mentioned in your edit) by using Any(ms => ...) instead inside of the Where.

Here is the full example.

this.SitesStore.DataSource = dc.Sites
    .Where(s => multipleSites.Any(ms => ms.Siteid == s.Siteid && s.Cid == int.Parse(Session["Cid"].ToString())))
    .Select(s => new { ... })
    .ToList();

So this should compile but some things to note:

This assumes the type of Cid is int.
It seems odd to me that you would need to call ToString() presuming the Session[] IS an array of strings. Conversely, if Session holds int already then there would be no need for int.Parse(...).

edited Mar 1, 2018 at 15:13

answered Mar 1, 2018 at 11:20

blins

2,53521 silver badges34 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Camilo Terevinto Over a year ago

Code dumps are not considered answers, please explain your code in the answer

Markiian Benovskyi Over a year ago

The op wants to use that select instead of Select(ms => ms.Siteid)

blins Over a year ago

Do they? The Select you mention is nested in the Where (predicate) and should be able to remain untouched.

Collectives™ on Stack Overflow

C# Lambda expression select new

1 Answer 1

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related