LINQ查询结果中WPF的构建列表

Question

What I need to learn how to construct List from query results

My DBContext:

public class Transport
{
    [Key]
    public int TransportID {get; set;}
    public string Model { get; set; }
    public string Brand { get; set; }
}

public class TransportOwner
{
    [Key]
    public int TransportOwnerID {get; set;}
    public int TransportID {get; set;}
    [ForeignKey("TransportID")]
    public virtual Transport Transport { get; set; }
}

public virtual DbSet<Transport> Transports { get; set; }
public virtual DbSet<TransportOwner> TransportOwners { get; set; }

In c# I created List:

private List<OwnerTransport> _ownerTransportList;

Also have a data from my DBContext:

var ownerTransport = DBContext.OwnerTransports.AsQueryable();

var queryResult = ownerTransport
        .Select(t => new
        {
            t.ID,
            t.PersonalCode,
            t.TransportID,
            Model = t.Transport.Model,
            Brand = t.Transport.Brand, 
        }).ToList();

queryResult I want to see in OwnersTransportList ant set is as ItemSource for my DataGrid

Answer 1

Consider using LINQ-to-Entities to execute filters on the data in the (DB) store before pulling the data into memory through EF.

For example, to populate your WPF GridControl, execute the following code. As an example for a possible filter, I included a where clause to filter for a specific TransportID .

public ICollection<OwnerTransport> GetOwnerTransportByTransportId(int transportId, int? skip = null, int? take = null)
{
    using (var context = new DBContext())
    {
       // base query
       var query = context.OwnerTranports.AsQueryable();

       // execute filter on transport ID
       query = query.Where(t => t.TransportID == transportId.Value);

       // apply skip/take
       if (skip.HasValue)
       {
           query = query.Skip(skip.Value);
       }
       if (take.HasValue)
       {
           query = query.Take(take.Value);
       }         

       // Materialize data. This pulls it from DB store into memory.
       var data = query.ToList();

       return data;
    }
}