Selecting multiple columns with linq query and lambda expression

Question

I'm new to C# ASP.NET, and am working on my first application.

I'm trying to create a linq statment that return an arrary.

I have a table of products. I want to be able to select name, id, and price, for each product where the status == 1.

I am struggling with crating a way to do this. I have only been able to return individual items/columns. I have been stuck on this wayyy to long.

This is what I have so far:

try
{
  using (UserDataDataContext db = new UserDataDataContext())
  {
    return db.mrobProducts.Select(x => x.Name).OrderBy(x => x).ToArray();
  }
}

If you look in the screen shot below, you can see I have 2 errors, Select = Type object can not be refered from it's usage ToArray = cant resolve symbol to array

enter image description here

I could not manage to put a where clause in, it would create an error, no matter where or how I was able to add it, — Mark
– Mark, Commented Aug 10, 2014 at 16:54
@GrantWinney, I've updated the question, as I have been implmenting everyones answer, and am still having issues here,,, — Mark
– Mark, Commented Aug 10, 2014 at 17:02

NinjaFart · Accepted Answer · 2018-12-30 21:33:55Z

32

Not sure what you table structure is like but see below.

public NamePriceModel[] AllProducts()
{
    try
    {
        using (UserDataDataContext db = new UserDataDataContext())
        {
            return db.mrobProducts
                .Where(x => x.Status == 1)
                .Select(x => new NamePriceModel { 
                    Name = x.Name, 
                    Id = x.Id, 
                    Price = x.Price
                })
                .OrderBy(x => x.Id)
                .ToArray();
         }
     }
     catch
     {
         return null;
     }
 }

This would return an array of type anonymous with the members you require.

Update:

Create a new class.

public class NamePriceModel 
{
    public string Name {get; set;}
    public decimal? Price {get; set;}
    public int Id {get; set;}
}

I've modified the query above to return this as well and you should change your method from returning string[] to returning NamePriceModel[].

edited Dec 30, 2018 at 21:33

NinjaFart

1,6241 gold badge20 silver badges26 bronze badges

answered Aug 10, 2014 at 16:48

scartag

17.7k3 gold badges52 silver badges53 bronze badges

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

7 Comments

Mark Over a year ago

The return get's an error, that says: Cant convert expression type Namstring, Pricestring to return type string[]

scartag Over a year ago

@Mark i'm not sure you have the right return type for the solution you are seeking. You might consider returning dynamic if you aren't interested in creating a type for it. A type would provide more clarity though.

Mark Over a year ago

@scaretag, would you be able to provide an example of this based on my updated question?

scartag Over a year ago

@Mark i've done that already. i've updated my answer with an example.

Farhad Jabiyev Over a year ago

OrderBy(x => x) will not work, if the class doesn't implement IComparable<T> interface in the NamePriceModel class. Or OP have to order by some column.

|

Farhad Jabiyev · Accepted Answer · 2014-08-10 17:10:11Z

12

You can use:

public YourClass[] AllProducts()
{
    try
    {
        using (UserDataDataContext db = new UserDataDataContext())
        {
            return db.mrobProducts.Where(x => x.Status == 1)
                           .OrderBy(x => x.ID)
                           .Select(x => new YourClass { ID = x.ID, Name = x.Name, Price = x.Price})
                           .ToArray();
        }
    }
    catch
    {
        return null;
    }
}

And here is YourClass implementation:

public class YourClass
{
  public string Name {get; set;}
  public int ID {get; set;}
  public int Price {get; set;}
}

And your AllProducts method's return type must be YourClass[].

edited Aug 10, 2014 at 17:10

answered Aug 10, 2014 at 16:49

Farhad Jabiyev

26.9k8 gold badges79 silver badges103 bronze badges

1 Comment

Prince Over a year ago

thanks for the answer . worked for me.optimized query.

Muru Bakthavachalam · Accepted Answer · 2014-12-13 23:59:59Z

7

using LINQ and Lamba, i wanted to return two field values and assign it to single entity object field;

as Name = Fname + " " + LName;

See my below code which is working as expected; hope this is useful;

Myentity objMyEntity = new Myentity
{
id = obj.Id,
Name = contxt.Vendors.Where(v => v.PQS_ID == obj.Id).Select(v=> new { contact = v.Fname + " " + v.LName}).Single().contact
}

no need to declare the 'contact'

answered Dec 13, 2014 at 23:59

Muru Bakthavachalam

1,35012 silver badges8 bronze badges

Comments

Varun Tej Reddy Putchakayala · Accepted Answer · 2018-11-22 12:22:13Z

2

        Object AccountObject = _dbContext.Accounts
                                   .Join(_dbContext.Users, acc => acc.AccountId, usr => usr.AccountId, (acc, usr) => new { acc, usr })
                                   .Where(x => x.usr.EmailAddress == key1)
                                   .Where(x => x.usr.Hash == key2)
                                   .Select(x => new { AccountId = x.acc.AccountId, Name = x.acc.Name })
                                   .SingleOrDefault();

answered Nov 22, 2018 at 12:22

Varun Tej Reddy Putchakayala

192 bronze badges

2 Comments

mrk Over a year ago

could you please Elaborate a Little on your proposed Code?

Varun Tej Reddy Putchakayala Over a year ago

Here Accounts and User tables are connected by AccountId foreign key. where condition applied on user table columns .We are selecting two columns from Accounts Table

Collectives™ on Stack Overflow

Selecting multiple columns with linq query and lambda expression

4 Answers 4

7 Comments

1 Comment

Comments

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

7 Comments

1 Comment

Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related