CODEWITHSUNDEEP
c#entity-frameworkc#-4.0
Riyaz
Riyaz

Reputation: 71

How To Get list Of Users

I am using Entity Framework 6 

public class ALLEvent
{
    [Key]
    public long Eventid { get; set; }
    public string eventname{ get; set; }
    public string AttendingUsers{ get; set; }
    public virtual List<User> Users{ get; set; }
}

public class Users
{
    [Key]
    public long id { get; set; }
    public string Name{ get; set; }
}

I have an AllEvent Class, in AttendingEvent property I have a list of attending UserIds separated by a comma. Is there any way I can get a list of attending users in the Users property of AllEvents?

Upvotes: 1

Views: 418

Answers (2)

Alexander Derck
Alexander Derck

Reputation: 14488

You will have to do a query for every event to get the users:

using(var ctx = new MyContext())
{
   ctx.Configuration.LazyLoadingEnabled = false;
   var events = ctx.AllEvent.ToList();

   foreach(var event in events)
   {
      event.Users = ctx.Users.Where(u => 
            event.AttendingUsers.Split(',').Cast<long>().ToList().Contains(u.id)).ToList();
   }
}

A much better option would be to make the Users have a foreignkey to an event (except if it's many to many, then you'll need an intermediate table). Then you can use lazy/eager loading. At the moment the virtual keyword doesn't do anything in your Event model because there's no relation between the entities.

Edited answer because cast from string -> long is needed.

Upvotes: 0

P. Wenger
P. Wenger

Reputation: 541

You could do it with Select:

allEvent.Users = allEvent.AttendingUsers.Split(',').Select(
u => new User
{
    Id = Convert.ToInt64(u)
}).ToList();

Or with a foreach loop:

var users = new List<Users>();
foreach (var u in allEvent.AttendingUsers.Split(',').ToList())
{
    users.Add(new Users
    {
        Id = Convert.ToInt64(u)
    });
}

allEvent.Users = users;

The Convert.ToInt64() method is used if you need a long type. But be aware, this could throw an exception.

https://msdn.microsoft.com/en-us/library/0zahhahw(v=vs.110).aspx

FormatException or OverflowException

Upvotes: 1

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