Concatenating two fields in LINQ select

Question

I have a dropdownlist, ddCourse, that I'm populating with the following LINQ query:

var db = new DataClasses1DataContext();
ddCourse.DisplayMember = "COURSE_TITLE";
ddCourse.ValueMember = "COURSE_ID";
ddCourse.DataSource = db.COURSE_MASTERs.OrderBy(c => c.COURSE_TITLE)
                                       .Select(c => new { c.COURSE_ID, c.COURSE_TITLE })
                                       .ToList();

There's another field, though, that I'd like to concatenate to the COURSE_TITLE field in my selection. So, I'd like my selection to look like:

.Select( c => new {c.COURSE_ID, c.CIN + " " + c.COURSE_TITLE})

The only problem is that this, apparently, isn't how it's done. I'm basically wanting to join c.CIN with c.COURSE_TITLE (and have a space in the middle). Can someone offer me some pointers on how to accomplish this?

The reason I want to do this is that, right now, the only thing appearing in the dropdownlist is the course title. I'd like to have the course ID number (CIN) concatenated to it when it displays.

EDIT: For clarification, I'm using Linq-to-SQL.

It's always important to mention any exception messages you get and also what flavor of LINQ you're working with (linq-to-sql I guess?). — Gert Arnold
– Gert Arnold, Commented Sep 20, 2013 at 21:02

Thilina H · Accepted Answer · 2013-09-20 20:56:13Z

16

use this

.Select( c => new {c.COURSE_ID, COURSE_TITLE =string.Format("{0} {1}" ,c.CIN ,c.COURSE_TITLE)})

answered Sep 20, 2013 at 20:56

Thilina H

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4 Comments

SouthShoreAK Over a year ago

I think string.Format will only work if the objects are already loaded into memory. I might be wrong, but I'm pretty sure Entity Framework will choke on that, and the posted code looks like it might be EF.

Si8 Over a year ago

How about for OrderBy?

balron Over a year ago

Simple and Great !

Developer Over a year ago

How can I convert this to string array

SouthShoreAK · Accepted Answer · 2013-09-20 20:51:21Z

6

You need to name your anonymous members:

.Select( c => new {COURSE_ID = c.COURSE_ID, COURSE_TITLE = c.CIN + " " + c.COURSE_TITLE})

answered Sep 20, 2013 at 20:51

SouthShoreAK

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1 Comment

c1phr Over a year ago

This solution worked for me in LINQ to Entities where string.Format would not. Thanks!

Cristian Lupascu · Accepted Answer · 2013-09-20 20:50:17Z

3

Write your Select like this:

.Select( c => new {c.COURSE_ID, COURSE_TITLE = c.CIN + " " + c.COURSE_TITLE})

Anonymous types need to have their column names specified, in case they cannot be inferred.

For c.COURSE_ID C# is smart enough to generate a member called COURSE_ID in the anonymous type. For the expression c.CIN + " " + c.COURSE_TITLE it cannot.

answered Sep 20, 2013 at 20:50

Cristian Lupascu

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