When using the multi-mapping APIs ensure you set the splitOn param if you have keys other than Id“, ”splitOn

Question

I\'m trying to use the Multi-mapping feature of dapper to return a list of Album and associated Artist and Genre.

public class Artist
{
public virtual int A         


        

Answer 1

I have faced same problem. Here is trick & example.

public abstract class BaseEntity
{
    [Key]
    public int Id { get; set; }
}

public class Category : BaseEntity
{
    public string Name { get; set; }
}


public class Status : BaseEntity
{
    public string Name { get; set; }
}

public class User : BaseEntity
{
    public string Name { get; set; }
    public string Surname { get; set; }
    public bool Active { get; set; }
}


public class TodoItem : BaseEntity
{
    public string Title { get; set; }
    public string Message { get; set; }
    public Status Status { get; set; }
    public Category Category { get; set; }
    public User User { get; set; }
    public DateTime CreatedOn { get; set; }
}

Using

            string sql = @"select 
                          t.Id,
                          t.Title,
                          t.Message,
                          t.CreatedOn,
                          s.Id as Id,
                          s.Name,

                          c.Id as Id,
                          c.Name,

                          u.Id as Id,
                          u.Name,
                          u.Surname,
                          u.Active

                         from ToDoItem t
                        inner join [Status] s on (t.StatusId = s.Id)
                        inner join [Category] c on (t.CategoryId = c.Id)
                        inner join [User] u on (t.AssignUserId = u.Id)";
            var result = connection.Query
                (sql, (todoItem, status, category, user) =>
            {
                todoItem.Status = status;
                todoItem.Category = category;
                todoItem.User = user;
                return todoItem;
            },splitOn: "Id,Id,Id,Id");

Here is trick splitOn: "Id,Id,Id,Id"