CODEWITHSUNDEEP
c#linq
Tom Gullen
Tom Gullen

Reputation: 61729

Linq select fields

Just experimenting with Linq:

    DataClassesDataContext db = new DataClassesDataContext();
    var q = from p in db.tblBlogEntries select p;
    foreach (var customer in q)
    {
        Response.Write(customer.ID + " " + customer.title + "\n");
    }

Works fine, but I can only seem to return 1 field, or all of them. How do I select say, p.ID and p.title, and nothing else?

Upvotes: 2

Views: 268

Answers (5)

BrokenGlass
BrokenGlass

Reputation: 160852

you need a projection to an anonymous type to only return the "parts" that you want:

 var q = from p in db.tblBlogEntries select new { p.ID, p.Title };

Alternatively you could also define a new class that only has the subset of the properties you want. This might be beneficial if you want to return instances of the projection, since anonymous types can only be used in local scope:

 var q = from p in db.tblBlogEntries 
         select new BlogTitleAndId() { ID = p.ID, Title = p.Title };

Upvotes: 8

user203570
user203570

Reputation:

How about this:

DataClassesDataContext db = new DataClassesDataContext();
var q = from p in db.tblBlogEntries select new { ID = p.ID, title = p.title };
foreach (var customer in q)
{
    Response.Write(customer.ID + " " + customer.title + "\n");
}

This part new { ID = p.ID, title = p.title } creates an anonymous class with members ID and title. You can add members for any column you wish and the types will be deduced automatically. Getting all the fields isn't that big a deal though. This article provides more information and a sample similar t yours.

Upvotes: 0

msarchet
msarchet

Reputation: 15232

var q = from p in db.tblBlogEntries select new {p.ID, p.Title}

Upvotes: 1

Adam Spicer
Adam Spicer

Reputation: 2721

Something like this...

DataClassesDataContext db = new DataClassesDataContext();
var q = from p in db.tblBlogEntries select new { Id = p.ID, Title = p.title };
foreach (var customer in q)
{
    Response.Write(customer.ID + " " + customer.title + "\n");
}

Upvotes: 1

jonathanpeppers
jonathanpeppers

Reputation: 26495

Instead of "select p"

Use:

var q = from p in db.tblBlogEntries select new { Column1 = p.Column1, Column2 = p.Column2 };

The new{} makes a inline class, so you can select whichever columns you need.

Upvotes: 1

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